Class: Sequel::Dataset
- Includes:
- Enumerable
- Defined in:
- lib/sequel_core/dataset.rb,
lib/sequel_core/dataset/sql.rb,
lib/sequel_core/object_graph.rb,
lib/sequel_core/dataset/query.rb,
lib/sequel_core/dataset/schema.rb,
lib/sequel_core/dataset/callback.rb,
lib/sequel_core/dataset/pagination.rb,
lib/sequel_core/dataset/convenience.rb,
lib/sequel_core/dataset/parse_tree_sequelizer.rb
Overview
A Dataset represents a view of a the data in a database, constrained by specific parameters such as filtering conditions, order, etc. Datasets can be used to create, retrieve, update and delete records.
Query results are always retrieved on demand, so a dataset can be kept around and reused indefinitely:
my_posts = DB[:posts].filter(:author => 'david') # no records are retrieved
p my_posts.all # records are now retrieved
...
p my_posts.all # records are retrieved again
In order to provide this functionality, dataset methods such as where, select, order, etc. return modified copies of the dataset, so you can use different datasets to access data:
posts = DB[:posts]
davids_posts = posts.filter(:author => 'david')
old_posts = posts.filter('stamp < ?', Date.today - 7)
Datasets are Enumerable objects, so they can be manipulated using any of the Enumerable methods, such as map, inject, etc.
The Dataset Adapter Interface
Each adapter should define its own dataset class as a descendant of Sequel::Dataset. The following methods should be overridden by the adapter Dataset class (each method with the stock implementation):
# Iterate over the results of the SQL query and call the supplied
# block with each record (as a hash).
def fetch_rows(sql, &block)
@db.synchronize do
r = @db.execute(sql)
r.each(&block)
end
end
# Insert records.
def insert(*values)
@db.synchronize do
@db.execute(insert_sql(*values)).last_insert_id
end
end
# Update records.
def update(*args, &block)
@db.synchronize do
@db.execute(update_sql(*args, &block)).affected_rows
end
end
# Delete records.
def delete(opts = nil)
@db.synchronize do
@db.execute(delete_sql(opts)).affected_rows
end
end
Methods added via metaprogramming
Some methods are added via metaprogramming:
-
! methods - These methods are the same as their non-! counterparts, but they modify the receiver instead of returning a modified copy of the dataset.
-
inner_join, full_outer_join, right_outer_join, left_outer_join - This methods are shortcuts to join_table with the join type already specified.
Direct Known Subclasses
ADO::Dataset, Adapter::Dataset, Sequel::DB2::Dataset, Sequel::DBI::Dataset, Informix::Dataset, JDBC::Dataset, MySQL::Dataset, ODBC::Dataset, OpenBase::Dataset, Oracle::Dataset, Postgres::Dataset, SQLite::Dataset
Defined Under Namespace
Modules: Pagination, QueryBlockCopy
Constant Summary collapse
- COLUMN_CHANGE_OPTS =
The dataset options that require the removal of cached columns if changed.
[:select, :sql, :from, :join].freeze
- DATASET_CLASSES =
Array of all subclasses of Dataset
[]
- MUTATION_METHODS =
All methods that should have a ! method added that modifies the receiver.
%w'and distinct exclude exists filter from from_self full_outer_join graph group group_and_count group_by having inner_join intersect invert join left_outer_join limit naked or order order_by order_more paginate query reject reverse reverse_order right_outer_join select select_all select_more set_graph_aliases set_model sort sort_by unfiltered union unordered where'.collect{|x| x.to_sym}
- NOTIMPL_MSG =
"This method must be overridden in Sequel adapters".freeze
- STOCK_TRANSFORMS =
{ :marshal => [ # for backwards-compatibility we support also non-base64-encoded values. proc {|v| Marshal.load(v.unpack('m')[0]) rescue Marshal.load(v)}, proc {|v| [Marshal.dump(v)].pack('m')} ], :yaml => [ proc {|v| YAML.load v if v}, proc {|v| v.to_yaml} ] }
- AND_SEPARATOR =
" AND ".freeze
- BOOL_FALSE =
"'f'".freeze
- BOOL_TRUE =
"'t'".freeze
- COLUMN_REF_RE1 =
/\A([\w ]+)__([\w ]+)___([\w ]+)\z/.freeze
- COLUMN_REF_RE2 =
/\A([\w ]+)___([\w ]+)\z/.freeze
- COLUMN_REF_RE3 =
/\A([\w ]+)__([\w ]+)\z/.freeze
- COUNT_FROM_SELF_OPTS =
[:distinct, :group, :sql]
- DATE_FORMAT =
"DATE '%Y-%m-%d'".freeze
- N_ARITY_OPERATORS =
::Sequel::SQL::ComplexExpression::N_ARITY_OPERATORS
- NULL =
"NULL".freeze
- QUESTION_MARK =
'?'.freeze
- STOCK_COUNT_OPTS =
{:select => ["COUNT(*)".lit], :order => nil}.freeze
- TIMESTAMP_FORMAT =
"TIMESTAMP '%Y-%m-%d %H:%M:%S'".freeze
- TWO_ARITY_OPERATORS =
::Sequel::SQL::ComplexExpression::TWO_ARITY_OPERATORS
- WILDCARD =
'*'.freeze
- COMMA_SEPARATOR =
', '.freeze
- COUNT_OF_ALL_AS_COUNT =
:count['*'.lit].as(:count)
Instance Attribute Summary collapse
-
#db ⇒ Object
The database that corresponds to this dataset.
-
#opts ⇒ Object
The hash of options for this dataset, keys are symbols.
-
#quote_identifiers ⇒ Object
writeonly
Whether to quote identifiers for this dataset.
-
#row_proc ⇒ Object
The row_proc for this database, should be a Proc that takes a single hash argument and returns the object you want to fetch_rows to return.
Class Method Summary collapse
-
.dataset_classes ⇒ Object
The array of dataset subclasses.
-
.def_mutation_method(*meths) ⇒ Object
Setup mutation (e.g. filter!) methods.
-
.inherited(c) ⇒ Object
Add the subclass to the array of subclasses.
Instance Method Summary collapse
-
#<<(*args) ⇒ Object
Alias for insert, but not aliased directly so subclasses don’t have to override both methods.
-
#[](*conditions) ⇒ Object
Returns the first record matching the conditions.
-
#[]=(conditions, values) ⇒ Object
Update all records matching the conditions with the values specified.
-
#aliased_expression_sql(ae) ⇒ Object
SQL fragment for the aliased expression.
-
#all(opts = nil, &block) ⇒ Object
Returns an array with all records in the dataset.
-
#and(*cond, &block) ⇒ Object
Adds an further filter to an existing filter using AND.
-
#as(aliaz) ⇒ Object
Return the dataset as a column with the given alias, so it can be used in the SELECT clause.
-
#avg(column) ⇒ Object
Returns the average value for the given column.
-
#case_expression_sql(ce) ⇒ Object
SQL fragment for specifying given CaseExpression.
-
#clone(opts = {}) ⇒ Object
Returns a new clone of the dataset with with the given options merged.
-
#column_all_sql(ca) ⇒ Object
SQL fragment for specifying all columns in a given table.
-
#columns ⇒ Object
Returns the columns in the result set in their true order.
-
#columns! ⇒ Object
Remove the cached list of columns and do a SELECT query to find the columns.
-
#complex_expression_sql(op, args) ⇒ Object
SQL fragment for complex expressions.
-
#count ⇒ Object
(also: #size)
Returns the number of records in the dataset.
-
#create_or_replace_view(name) ⇒ Object
Creates or replaces a view in the database with the given named based on the current dataset.
-
#create_view(name) ⇒ Object
Creates a view in the database with the given named based on the current dataset.
-
#def_mutation_method(*meths) ⇒ Object
Add a mutation method to this dataset instance.
-
#delete(opts = nil) ⇒ Object
Deletes the records in the dataset.
-
#delete_sql(opts = nil) ⇒ Object
Formats a DELETE statement using the given options and dataset options.
-
#each(opts = nil, &block) ⇒ Object
Iterates over the records in the dataset.
-
#each_page(page_size, &block) ⇒ Object
Yields a paginated dataset for each page and returns the receiver.
-
#empty? ⇒ Boolean
Returns true if no records exists in the dataset.
-
#except(dataset, all = false) ⇒ Object
Adds an EXCEPT clause using a second dataset object.
-
#exclude(*cond, &block) ⇒ Object
Performs the inverse of Dataset#filter.
-
#exists(opts = nil) ⇒ Object
Returns an EXISTS clause for the dataset.
-
#fetch_rows(sql, &block) ⇒ Object
Executes a select query and fetches records, passing each record to the supplied block.
-
#filter(*cond, &block) ⇒ Object
(also: #where)
Returns a copy of the dataset with the given conditions imposed upon it.
-
#first(*args, &block) ⇒ Object
Returns the first record in the dataset.
-
#first_source ⇒ Object
The first source (primary table) for this dataset.
-
#from(*source) ⇒ Object
Returns a copy of the dataset with the source changed.
-
#from_self ⇒ Object
Returns a dataset selecting from the current dataset.
-
#function_sql(f) ⇒ Object
SQL fragment specifying an SQL function call.
-
#get(column) ⇒ Object
Return the column value for the first matching record in the dataset.
-
#graph(dataset, join_conditions, options = {}) ⇒ Object
Allows you to join multiple datasets/tables and have the result set split into component tables.
-
#grep(cols, terms) ⇒ Object
Pattern match any of the columns to any of the terms.
-
#group(*columns) ⇒ Object
(also: #group_by)
Returns a copy of the dataset with the results grouped by the value of the given columns.
-
#group_and_count(*columns) ⇒ Object
Returns a dataset grouped by the given column with count by group.
-
#having(*cond, &block) ⇒ Object
Returns a copy of the dataset with the having conditions changed.
-
#initialize(db, opts = nil) ⇒ Dataset
constructor
Constructs a new instance of a dataset with an associated database and options.
-
#insert(*values) ⇒ Object
Inserts values into the associated table.
-
#insert_multiple(array, &block) ⇒ Object
Inserts multiple values.
-
#insert_sql(*values) ⇒ Object
Formats an INSERT statement using the given values.
-
#inspect ⇒ Object
Returns a string representation of the dataset including the class name and the corresponding SQL select statement.
-
#intersect(dataset, all = false) ⇒ Object
Adds an INTERSECT clause using a second dataset object.
-
#interval(column) ⇒ Object
Returns the interval between minimum and maximum values for the given column.
-
#invert ⇒ Object
Inverts the current filter.
-
#irregular_function_sql(f) ⇒ Object
SQL fragment specifying an Irregular (cast/extract) SQL function call.
-
#join_clause_sql(jc) ⇒ Object
SQL fragment specifying a JOIN clause without ON or USING.
-
#join_on_clause_sql(jc) ⇒ Object
SQL fragment specifying a JOIN clause with ON.
-
#join_table(type, table, expr = nil, table_alias = nil, &block) ⇒ Object
Returns a joined dataset.
-
#join_using_clause_sql(jc) ⇒ Object
SQL fragment specifying a JOIN clause with USING.
-
#last(*args, &block) ⇒ Object
Reverses the order and then runs first.
-
#limit(l, o = nil) ⇒ Object
If given an integer, the dataset will contain only the first l results.
-
#literal(v) ⇒ Object
Returns a literal representation of a value to be used as part of an SQL expression.
-
#map(column_name = nil, &block) ⇒ Object
Maps column values for each record in the dataset (if a column name is given), or performs the stock mapping functionality of Enumerable.
-
#max(column) ⇒ Object
Returns the maximum value for the given column.
-
#min(column) ⇒ Object
Returns the minimum value for the given column.
-
#model_classes ⇒ Object
Returns the the model classes associated with the dataset as a hash.
-
#multi_insert(*args) ⇒ Object
(also: #import)
Inserts multiple records into the associated table.
-
#multi_insert_sql(columns, values) ⇒ Object
Returns an array of insert statements for inserting multiple records.
-
#naked ⇒ Object
Returns a naked dataset clone - i.e.
-
#or(*cond, &block) ⇒ Object
Adds an alternate filter to an existing filter using OR.
-
#order(*order) ⇒ Object
(also: #order_by)
Returns a copy of the dataset with the order changed.
-
#order_more(*order) ⇒ Object
Returns a copy of the dataset with the order columns added to the existing order.
-
#ordered_expression_sql(oe) ⇒ Object
SQL fragment for the ordered expression, used in the ORDER BY clause.
-
#paginate(page_no, page_size, record_count = nil) ⇒ Object
Returns a paginated dataset.
-
#polymorphic_key ⇒ Object
Returns the column name for the polymorphic key.
-
#print(*cols) ⇒ Object
Pretty prints the records in the dataset as plain-text table.
-
#qualified_identifier_sql(qcr) ⇒ Object
SQL fragment for the qualifed identifier, specifying a table and a column (or schema and table).
-
#query(&block) ⇒ Object
Translates a query block into a dataset.
-
#quote_identifier(name) ⇒ Object
(also: #quote_column_ref)
Adds quoting to identifiers (columns and tables).
-
#quote_identifiers? ⇒ Boolean
Whether this dataset quotes identifiers.
-
#quoted_identifier(name) ⇒ Object
This method quotes the given name with the SQL standard double quote.
-
#range(column) ⇒ Object
Returns a Range object made from the minimum and maximum values for the given column.
-
#reverse_order(*order) ⇒ Object
(also: #reverse)
Returns a copy of the dataset with the order reversed.
-
#select(*columns) ⇒ Object
Returns a copy of the dataset with the columns selected changed to the given columns.
-
#select_all ⇒ Object
Returns a copy of the dataset selecting the wildcard.
-
#select_more(*columns) ⇒ Object
Returns a copy of the dataset with the given columns added to the existing selected columns.
-
#select_sql(opts = nil) ⇒ Object
(also: #sql)
Formats a SELECT statement using the given options and the dataset options.
-
#set(*args, &block) ⇒ Object
Alias for set, but not aliased directly so subclasses don’t have to override both methods.
-
#set_graph_aliases(graph_aliases) ⇒ Object
This allows you to manually specify the graph aliases to use when using graph.
-
#set_model(key, *args) ⇒ Object
Associates or disassociates the dataset with a model(s).
-
#single_record(opts = nil) ⇒ Object
Returns the first record in the dataset.
-
#single_value(opts = nil) ⇒ Object
Returns the first value of the first record in the dataset.
-
#subscript_sql(s) ⇒ Object
SQL fragment for specifying subscripts (SQL arrays).
-
#sum(column) ⇒ Object
Returns the sum for the given column.
-
#symbol_to_column_ref(sym) ⇒ Object
Converts a symbol into a column name.
-
#table_exists? ⇒ Boolean
Returns true if the table exists.
-
#to_csv(include_column_titles = true) ⇒ Object
Returns a string in CSV format containing the dataset records.
-
#to_hash(key_column, value_column = nil) ⇒ Object
Returns a hash with one column used as key and another used as value.
-
#transform(t) ⇒ Object
Sets a value transform which is used to convert values loaded and saved to/from the database.
-
#transform_load(r) ⇒ Object
Applies the value transform for data loaded from the database.
-
#transform_save(r) ⇒ Object
Applies the value transform for data saved to the database.
-
#unfiltered ⇒ Object
Returns a copy of the dataset with no filters (HAVING or WHERE clause) applied.
-
#union(dataset, all = false) ⇒ Object
Adds a UNION clause using a second dataset object.
-
#uniq(*args) ⇒ Object
(also: #distinct)
Returns a copy of the dataset with the distinct option.
-
#unordered ⇒ Object
Returns a copy of the dataset with no order.
-
#update(values, opts = nil) ⇒ Object
Updates values for the dataset.
-
#update_sql(values = {}, opts = nil, &block) ⇒ Object
Formats an UPDATE statement using the given values.
Methods included from Enumerable
Constructor Details
#initialize(db, opts = nil) ⇒ Dataset
Constructs a new instance of a dataset with an associated database and options. Datasets are usually constructed by invoking Database methods:
DB[:posts]
Or:
DB.dataset # the returned dataset is blank
Sequel::Dataset is an abstract class that is not useful by itself. Each database adaptor should provide a descendant class of Sequel::Dataset.
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# File 'lib/sequel_core/dataset.rb', line 131 def initialize(db, opts = nil) @db = db @quote_identifiers = db.quote_identifiers? if db.respond_to?(:quote_identifiers?) @opts = opts || {} @row_proc = nil @transform = nil end |
Instance Attribute Details
#db ⇒ Object
The database that corresponds to this dataset
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# File 'lib/sequel_core/dataset.rb', line 107 def db @db end |
#opts ⇒ Object
The hash of options for this dataset, keys are symbols.
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# File 'lib/sequel_core/dataset.rb', line 110 def opts @opts end |
#quote_identifiers=(value) ⇒ Object (writeonly)
Whether to quote identifiers for this dataset
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# File 'lib/sequel_core/dataset.rb', line 118 def quote_identifiers=(value) @quote_identifiers = value end |
#row_proc ⇒ Object
The row_proc for this database, should be a Proc that takes a single hash argument and returns the object you want to fetch_rows to return.
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# File 'lib/sequel_core/dataset.rb', line 115 def row_proc @row_proc end |
Class Method Details
.dataset_classes ⇒ Object
The array of dataset subclasses.
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# File 'lib/sequel_core/dataset.rb', line 142 def self.dataset_classes DATASET_CLASSES end |
.def_mutation_method(*meths) ⇒ Object
Setup mutation (e.g. filter!) methods. These operate the same as the non-! methods, but replace the options of the current dataset with the options of the resulting dataset.
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# File 'lib/sequel_core/dataset.rb', line 149 def self.def_mutation_method(*meths) meths.each do |meth| class_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end") end end |
.inherited(c) ⇒ Object
Add the subclass to the array of subclasses.
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# File 'lib/sequel_core/dataset.rb', line 156 def self.inherited(c) DATASET_CLASSES << c end |
Instance Method Details
#<<(*args) ⇒ Object
Alias for insert, but not aliased directly so subclasses don’t have to override both methods.
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# File 'lib/sequel_core/dataset.rb', line 164 def <<(*args) insert(*args) end |
#[](*conditions) ⇒ Object
Returns the first record matching the conditions.
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# File 'lib/sequel_core/dataset/convenience.rb', line 7 def [](*conditions) first(*conditions) end |
#[]=(conditions, values) ⇒ Object
Update all records matching the conditions with the values specified.
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# File 'lib/sequel_core/dataset/convenience.rb', line 13 def []=(conditions, values) filter(conditions).update(values) end |
#aliased_expression_sql(ae) ⇒ Object
SQL fragment for the aliased expression
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# File 'lib/sequel_core/dataset/sql.rb', line 28 def aliased_expression_sql(ae) "#{literal(ae.expression)} AS #{quote_identifier(ae.aliaz)}" end |
#all(opts = nil, &block) ⇒ Object
Returns an array with all records in the dataset. If a block is given, the array is iterated over after all items have been loaded.
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# File 'lib/sequel_core/dataset.rb', line 176 def all(opts = nil, &block) a = [] each(opts) {|r| a << r} post_load(a) a.each(&block) if block a end |
#and(*cond, &block) ⇒ Object
Adds an further filter to an existing filter using AND. If no filter exists an error is raised. This method is identical to #filter except it expects an existing filter.
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# File 'lib/sequel_core/dataset/sql.rb', line 22 def and(*cond, &block) raise(Error::NoExistingFilter, "No existing filter found.") unless @opts[:having] || @opts[:where] filter(*cond, &block) end |
#as(aliaz) ⇒ Object
Return the dataset as a column with the given alias, so it can be used in the SELECT clause. This dataset should result in a single row and a single column.
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# File 'lib/sequel_core/dataset.rb', line 170 def as(aliaz) ::Sequel::SQL::AliasedExpression.new(self, aliaz) end |
#avg(column) ⇒ Object
Returns the average value for the given column.
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# File 'lib/sequel_core/dataset/convenience.rb', line 18 def avg(column) get(:avg[column]) end |
#case_expression_sql(ce) ⇒ Object
SQL fragment for specifying given CaseExpression.
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# File 'lib/sequel_core/dataset/sql.rb', line 33 def case_expression_sql(ce) "(CASE #{ce.conditions.collect{|c,r| "WHEN #{literal(c)} THEN #{literal(r)} "}.join}ELSE #{literal(ce.default)} END)" end |
#clone(opts = {}) ⇒ Object
Returns a new clone of the dataset with with the given options merged. If the options changed include options in COLUMN_CHANGE_OPTS, the cached columns are deleted.
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# File 'lib/sequel_core/dataset.rb', line 187 def clone(opts = {}) c = super() c.opts = @opts.merge(opts) c.instance_variable_set(:@columns, nil) if c.(COLUMN_CHANGE_OPTS) c end |
#column_all_sql(ca) ⇒ Object
SQL fragment for specifying all columns in a given table.
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# File 'lib/sequel_core/dataset/sql.rb', line 38 def column_all_sql(ca) "#{quote_identifier(ca.table)}.*" end |
#columns ⇒ Object
Returns the columns in the result set in their true order. If the columns are currently cached, returns the cached value. Otherwise, a SELECT query is performed to get a single row. Adapters are expected to fill the columns cache with the column information when a query is performed. If the dataset does not have any rows, this will be an empty array. If you are looking for all columns for a single table, see Schema::SQL#schema.
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# File 'lib/sequel_core/dataset.rb', line 200 def columns single_record unless @columns @columns || [] end |
#columns! ⇒ Object
Remove the cached list of columns and do a SELECT query to find the columns.
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# File 'lib/sequel_core/dataset.rb', line 207 def columns! @columns = nil columns end |
#complex_expression_sql(op, args) ⇒ Object
SQL fragment for complex expressions
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# File 'lib/sequel_core/dataset/sql.rb', line 43 def complex_expression_sql(op, args) case op when *TWO_ARITY_OPERATORS "(#{literal(args.at(0))} #{op} #{literal(args.at(1))})" when *N_ARITY_OPERATORS "(#{args.collect{|a| literal(a)}.join(" #{op} ")})" when :NOT "NOT #{literal(args.at(0))}" when :NOOP literal(args.at(0)) when :'B~' "~#{literal(args.at(0))}" else raise(Sequel::Error, "invalid operator #{op}") end end |
#count ⇒ Object Also known as: size
Returns the number of records in the dataset.
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# File 'lib/sequel_core/dataset/sql.rb', line 61 def count (COUNT_FROM_SELF_OPTS) ? from_self.count : single_value(STOCK_COUNT_OPTS).to_i end |
#create_or_replace_view(name) ⇒ Object
Creates or replaces a view in the database with the given named based on the current dataset.
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# File 'lib/sequel_core/dataset/schema.rb', line 11 def create_or_replace_view(name) @db.create_or_replace_view(name, self) end |
#create_view(name) ⇒ Object
Creates a view in the database with the given named based on the current dataset.
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# File 'lib/sequel_core/dataset/schema.rb', line 5 def create_view(name) @db.create_view(name, self) end |
#def_mutation_method(*meths) ⇒ Object
Add a mutation method to this dataset instance.
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# File 'lib/sequel_core/dataset.rb', line 213 def def_mutation_method(*meths) meths.each do |meth| instance_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end") end end |
#delete(opts = nil) ⇒ Object
Deletes the records in the dataset. Adapters should override this method.
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# File 'lib/sequel_core/dataset.rb', line 220 def delete(opts = nil) raise NotImplementedError, NOTIMPL_MSG end |
#delete_sql(opts = nil) ⇒ Object
Formats a DELETE statement using the given options and dataset options.
dataset.filter(:price >= 100).delete_sql #=>
"DELETE FROM items WHERE (price >= 100)"
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# File 'lib/sequel_core/dataset/sql.rb', line 70 def delete_sql(opts = nil) opts = opts ? @opts.merge(opts) : @opts if opts[:group] raise Error::InvalidOperation, "Grouped datasets cannot be deleted from" elsif opts[:from].is_a?(Array) && opts[:from].size > 1 raise Error::InvalidOperation, "Joined datasets cannot be deleted from" end sql = "DELETE FROM #{source_list(opts[:from])}" if where = opts[:where] sql << " WHERE #{literal(where)}" end sql end |
#each(opts = nil, &block) ⇒ Object
Iterates over the records in the dataset.
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# File 'lib/sequel_core/dataset.rb', line 225 def each(opts = nil, &block) if graph = @opts[:graph] graph_each(opts, &block) else row_proc = @row_proc unless opts && opts[:naked] transform = @transform fetch_rows(select_sql(opts)) do |r| r = transform_load(r) if transform r = row_proc[r] if row_proc yield r end end self end |
#each_page(page_size, &block) ⇒ Object
Yields a paginated dataset for each page and returns the receiver. Does a count to find the total number of records for this dataset.
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# File 'lib/sequel_core/dataset/pagination.rb', line 16 def each_page(page_size, &block) raise(Error, "You cannot paginate a dataset that already has a limit") if @opts[:limit] record_count = count total_pages = (record_count / page_size.to_f).ceil (1..total_pages).each{|page_no| yield paginate(page_no, page_size, record_count)} self end |
#empty? ⇒ Boolean
Returns true if no records exists in the dataset
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# File 'lib/sequel_core/dataset/convenience.rb', line 23 def empty? db.dataset.where(exists).get(1) == nil end |
#except(dataset, all = false) ⇒ Object
Adds an EXCEPT clause using a second dataset object. If all is true the clause used is EXCEPT ALL, which may return duplicate rows.
DB[:items].except(DB[:other_items]).sql
#=> "SELECT * FROM items EXCEPT SELECT * FROM other_items"
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# File 'lib/sequel_core/dataset/sql.rb', line 93 def except(dataset, all = false) clone(:except => dataset, :except_all => all) end |
#exclude(*cond, &block) ⇒ Object
Performs the inverse of Dataset#filter.
dataset.exclude(:category => 'software').sql #=>
"SELECT * FROM items WHERE (category != 'software')"
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# File 'lib/sequel_core/dataset/sql.rb', line 101 def exclude(*cond, &block) clause = (@opts[:having] ? :having : :where) cond = cond.first if cond.size == 1 cond = cond.sql_or if (Hash === cond) || ((Array === cond) && (cond.all_two_pairs?)) cond = filter_expr(cond, &block) cond = SQL::BooleanExpression.invert(cond) cond = SQL::BooleanExpression.new(:AND, @opts[clause], cond) if @opts[clause] clone(clause => cond) end |
#exists(opts = nil) ⇒ Object
Returns an EXISTS clause for the dataset.
DB.select(1).where(DB[:items].exists).sql
#=> "SELECT 1 WHERE EXISTS (SELECT * FROM items)"
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# File 'lib/sequel_core/dataset/sql.rb', line 115 def exists(opts = nil) "EXISTS (#{select_sql(opts)})" end |
#fetch_rows(sql, &block) ⇒ Object
Executes a select query and fetches records, passing each record to the supplied block. Adapters should override this method.
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# File 'lib/sequel_core/dataset.rb', line 242 def fetch_rows(sql, &block) raise NotImplementedError, NOTIMPL_MSG end |
#filter(*cond, &block) ⇒ Object Also known as: where
Returns a copy of the dataset with the given conditions imposed upon it.
If the query has been grouped, then the conditions are imposed in the HAVING clause. If not, then they are imposed in the WHERE clause. Filter
filter accepts the following argument types:
-
Hash - list of equality expressions
-
Array - depends:
-
If first member is a string, assumes the rest of the arguments are parameters and interpolates them into the string.
-
If all members are arrays of length two, treats the same way as a hash, except it allows for duplicate keys to be specified.
-
-
String - taken literally
-
Symbol - taken as a boolean column argument (e.g. WHERE active)
-
Sequel::SQL::BooleanExpression - an existing condition expression, probably created using the Sequel blockless filter DSL.
filter also takes a block, but use of this is discouraged as it requires ParseTree.
Examples:
dataset.filter(:id => 3).sql #=>
"SELECT * FROM items WHERE (id = 3)"
dataset.filter('price < ?', 100).sql #=>
"SELECT * FROM items WHERE price < 100"
dataset.filter([[:id, (1,2,3)], [:id, 0..10]]).sql #=>
"SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10)))"
dataset.filter('price < 100').sql #=>
"SELECT * FROM items WHERE price < 100"
dataset.filter(:active).sql #=>
"SELECT * FROM items WHERE :active
dataset.filter(:price < 100).sql #=>
"SELECT * FROM items WHERE (price < 100)"
Multiple filter calls can be chained for scoping:
software = dataset.filter(:category => 'software')
software.filter(price < 100).sql #=>
"SELECT * FROM items WHERE ((category = 'software') AND (price < 100))"
See doc/dataset_filters.rdoc for more examples and details.
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# File 'lib/sequel_core/dataset/sql.rb', line 162 def filter(*cond, &block) clause = (@opts[:having] ? :having : :where) cond = cond.first if cond.size == 1 cond = transform_save(cond) if @transform if cond.is_a?(Hash) cond = filter_expr(cond, &block) cond = SQL::BooleanExpression.new(:AND, @opts[clause], cond) if @opts[clause] && !@opts[clause].blank? clone(clause => cond) end |
#first(*args, &block) ⇒ Object
Returns the first record in the dataset. If a numeric argument is given, it is interpreted as a limit, and then returns all matching records up to that limit. If no argument is passed, it returns the first matching record. If any other type of argument(s) is passed, it is given to filter and the first matching record is returned. If a block is given, it is used to filter the dataset before returning anything.
Examples:
ds.first => {:id=>7}
ds.first(2) => [{:id=>6}, {:id=>4}]
ds.order(:id).first(2) => [{:id=>1}, {:id=>2}]
ds.first(:id=>2) => {:id=>2}
ds.first("id = 3") => {:id=>3}
ds.first("id = ?", 4) => {:id=>4}
ds.first{:id > 2} => {:id=>5}
ds.order(:id).first{:id > 2} => {:id=>3}
ds.first{:id > 2} => {:id=>5}
ds.first("id > ?", 4){:id < 6) => {:id=>5}
ds.order(:id).first(2){:id < 2} => [{:id=>1}]
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# File 'lib/sequel_core/dataset/convenience.rb', line 48 def first(*args, &block) ds = block ? filter(&block) : self if args.empty? ds.single_record else args = (args.size == 1) ? args.first : args if Integer === args ds.limit(args).all else ds.filter(args).single_record end end end |
#first_source ⇒ Object
The first source (primary table) for this dataset. If the dataset doesn’t have a table, raises an error. If the table is aliased, returns the actual table name, not the alias.
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# File 'lib/sequel_core/dataset/sql.rb', line 175 def first_source source = @opts[:from] if source.nil? || source.empty? raise Error, 'No source specified for query' end case s = source.first when Hash s.values.first when Symbol sch, table, aliaz = split_symbol(s) aliaz ? aliaz.to_sym : s else s end end |
#from(*source) ⇒ Object
Returns a copy of the dataset with the source changed.
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# File 'lib/sequel_core/dataset/sql.rb', line 192 def from(*source) clone(:from => source) end |
#from_self ⇒ Object
Returns a dataset selecting from the current dataset.
ds = DB[:items].order(:name)
ds.sql #=> "SELECT * FROM items ORDER BY name"
ds.from_self.sql #=> "SELECT * FROM (SELECT * FROM items ORDER BY name)"
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# File 'lib/sequel_core/dataset/sql.rb', line 201 def from_self fs = {} @opts.keys.each{|k| fs[k] = nil} fs[:from] = [self] clone(fs) end |
#function_sql(f) ⇒ Object
SQL fragment specifying an SQL function call
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# File 'lib/sequel_core/dataset/sql.rb', line 209 def function_sql(f) args = f.args "#{f.f}#{args.empty? ? '()' : literal(args)}" end |
#get(column) ⇒ Object
Return the column value for the first matching record in the dataset.
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# File 'lib/sequel_core/dataset/convenience.rb', line 64 def get(column) select(column).single_value end |
#graph(dataset, join_conditions, options = {}) ⇒ Object
Allows you to join multiple datasets/tables and have the result set split into component tables.
This differs from the usual usage of join, which returns the result set as a single hash. For example:
# CREATE TABLE artists (id INTEGER, name TEXT);
# CREATE TABLE albums (id INTEGER, name TEXT, artist_id INTEGER);
DB[:artists].left_outer_join(:albums, :artist_id=>:id).first
=> {:id=>(albums.id||artists.id), :name=>(albums.name||artist.names), :artist_id=>albums.artist_id}
DB[:artists].graph(:albums, :artist_id=>:id).first
=> {:artists=>{:id=>artists.id, :name=>artists.name}, :albums=>{:id=>albums.id, :name=>albums.name, :artist_id=>albums.artist_id}}
Using a join such as left_outer_join, the attribute names that are shared between the tables are combined in the single return hash. You can get around that by using .select with correct aliases for all of the columns, but it is simpler to use graph and have the result set split for you. In addition, graph respects any row_proc or transform attributes of the current dataset and the datasets you use with graph.
If you are graphing a table and all columns for that table are nil, this indicates that no matching rows existed in the table, so graph will return nil instead of a hash with all nil values:
# If the artist doesn't have any albums
DB[:artists].graph(:albums, :artist_id=>:id).first
=> {:artists=>{:id=>artists.id, :name=>artists.name}, :albums=>nil}
Arguments:
-
dataset - Can be a symbol (specifying a table), another dataset, or an object that responds to .dataset and yields a symbol or a dataset
-
join_conditions - A conditions hash that is passed to the join_table method
-
options - A hash of graph options. The following options are currently used:
-
:table_alias - The alias to use for the table. If not specified, doesn’t alias the table. You will get an error if the the alias (or table) name is used more than once.
-
:join_type - The type of join to use (passed to join_table). Defaults to :left_outer.
-
:select - An array of columns to select. When not used, selects all columns in the given dataset. When set to false, selects no columns and is like simply joining the tables, though graph keeps some metadata about join that makes it important to use graph instead of join.
-
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# File 'lib/sequel_core/object_graph.rb', line 46 def graph(dataset, join_conditions, = {}) # Allow the use of a model, dataset, or symbol as the first argument # Find the table name/dataset based on the argument dataset = dataset.dataset if dataset.respond_to?(:dataset) case dataset when Symbol table = dataset dataset = @db[dataset] when ::Sequel::Dataset table = dataset.first_source else raise Error, "The dataset argument should be a symbol, dataset, or model" end # Raise Sequel::Error with explanation that the table alias has been used raise_alias_error = lambda do raise(Error, "this #{[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \ "#{[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") end # Only allow table aliases that haven't been used table_alias = [:table_alias] || table raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias) # Join the table early in order to avoid cloning the dataset twice ds = join_table([:join_type] || :left_outer, table, join_conditions, table_alias) opts = ds.opts # Whether to include the table in the result set add_table = [:select] == false ? false : true # Whether to add the columns to the list of column aliases add_columns = !ds.opts.include?(:graph_aliases) # Setup the initial graph data structure if it doesn't exist unless graph = opts[:graph] master = ds.first_source raise_alias_error.call if master == table_alias # Master hash storing all .graph related information graph = opts[:graph] = {} # Associates column aliases back to tables and columns column_aliases = graph[:column_aliases] = {} # Associates table alias (the master is never aliased) table_aliases = graph[:table_aliases] = {master=>self} # Keep track of the alias numbers used ca_num = graph[:column_alias_num] = {} # All columns in the master table are never # aliased, but are not included if set_graph_aliases # has been used. if add_columns select = (opts[:select] ||= []) columns.each do |column| column_aliases[column] = [master, column] select.push(:"#{master}__#{column}") end end end # Add the table alias to the list of aliases # Even if it isn't been used in the result set, # we add a key for it with a nil value so we can check if it # is used more than once table_aliases = graph[:table_aliases] table_aliases[table_alias] = add_table ? dataset : nil # Add the columns to the selection unless we are ignoring them if add_table && add_columns select = opts[:select] column_aliases = graph[:column_aliases] ca_num = graph[:column_alias_num] # Which columns to add to the result set cols = [:select] || dataset.columns # If the column hasn't been used yet, don't alias it. # If it has been used, try table_column. # If that has been used, try table_column_N # using the next value of N that we know hasn't been # used cols.each do |column| col_alias, c = if column_aliases[column] tc = :"#{table_alias}_#{column}" if column_aliases[tc] if can = ca_num[tc] ca_num[tc] += 1 tc = :"#{tc}_#{can}" else ca_num[tc] = 1 tc = :"#{tc}_0" end end [tc, :"#{table_alias}__#{column}___#{tc}"] else [column, :"#{table_alias}__#{column}"] end column_aliases[col_alias] = [table_alias, column] select.push(c) end end ds end |
#grep(cols, terms) ⇒ Object
Pattern match any of the columns to any of the terms. The terms can be strings (which use LIKE) or regular expressions (which are only supported in some databases). See Sequel::SQL::StringExpression.like. Note that the total number of pattern matches will be cols.length * terms.length, which could cause performance issues.
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# File 'lib/sequel_core/dataset/sql.rb', line 219 def grep(cols, terms) filter(SQL::BooleanExpression.new(:OR, *Array(cols).collect{|c| SQL::StringExpression.like(c, *terms)})) end |
#group(*columns) ⇒ Object Also known as: group_by
Returns a copy of the dataset with the results grouped by the value of the given columns
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# File 'lib/sequel_core/dataset/sql.rb', line 225 def group(*columns) clone(:group => columns) end |
#group_and_count(*columns) ⇒ Object
Returns a dataset grouped by the given column with count by group.
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# File 'lib/sequel_core/dataset/convenience.rb', line 69 def group_and_count(*columns) group(*columns).select(*(columns + [COUNT_OF_ALL_AS_COUNT])).order(:count) end |
#having(*cond, &block) ⇒ Object
Returns a copy of the dataset with the having conditions changed. Raises an error if the dataset has not been grouped. See also #filter.
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# File 'lib/sequel_core/dataset/sql.rb', line 232 def having(*cond, &block) raise(Error::InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") unless @opts[:group] clone(:having=>{}).filter(*cond, &block) end |
#insert(*values) ⇒ Object
Inserts values into the associated table. Adapters should override this method.
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# File 'lib/sequel_core/dataset.rb', line 248 def insert(*values) raise NotImplementedError, NOTIMPL_MSG end |
#insert_multiple(array, &block) ⇒ Object
Inserts multiple values. If a block is given it is invoked for each item in the given array before inserting it. See #multi_insert as a possible faster version that inserts multiple records in one SQL statement.
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# File 'lib/sequel_core/dataset/sql.rb', line 241 def insert_multiple(array, &block) if block array.each {|i| insert(block[i])} else array.each {|i| insert(i)} end end |
#insert_sql(*values) ⇒ Object
Formats an INSERT statement using the given values. If a hash is given, the resulting statement includes column names. If no values are given, the resulting statement includes a DEFAULT VALUES clause.
dataset.insert_sql() #=> 'INSERT INTO items DEFAULT VALUES'
dataset.insert_sql(1,2,3) #=> 'INSERT INTO items VALUES (1, 2, 3)'
dataset.insert_sql(:a => 1, :b => 2) #=>
'INSERT INTO items (a, b) VALUES (1, 2)'
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# File 'lib/sequel_core/dataset/sql.rb', line 257 def insert_sql(*values) if values.empty? insert_default_values_sql else values = values[0] if values.size == 1 # if hash or array with keys we need to transform the values if @transform && (values.is_a?(Hash) || (values.is_a?(Array) && values.keys)) values = transform_save(values) end from = source_list(@opts[:from]) case values when Array if values.empty? insert_default_values_sql else "INSERT INTO #{from} VALUES #{literal(values)}" end when Hash if values.empty? insert_default_values_sql else fl, vl = [], [] values.each {|k, v| fl << literal(k.is_a?(String) ? k.to_sym : k); vl << literal(v)} "INSERT INTO #{from} (#{fl.join(COMMA_SEPARATOR)}) VALUES (#{vl.join(COMMA_SEPARATOR)})" end when Dataset "INSERT INTO #{from} #{literal(values)}" else if values.respond_to?(:values) insert_sql(values.values) else "INSERT INTO #{from} VALUES (#{literal(values)})" end end end end |
#inspect ⇒ Object
Returns a string representation of the dataset including the class name and the corresponding SQL select statement.
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# File 'lib/sequel_core/dataset.rb', line 254 def inspect "#<#{self.class}: #{sql.inspect}>" end |
#intersect(dataset, all = false) ⇒ Object
Adds an INTERSECT clause using a second dataset object. If all is true the clause used is INTERSECT ALL, which may return duplicate rows.
DB[:items].intersect(DB[:other_items]).sql
#=> "SELECT * FROM items INTERSECT SELECT * FROM other_items"
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# File 'lib/sequel_core/dataset/sql.rb', line 301 def intersect(dataset, all = false) clone(:intersect => dataset, :intersect_all => all) end |
#interval(column) ⇒ Object
Returns the interval between minimum and maximum values for the given column.
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# File 'lib/sequel_core/dataset/convenience.rb', line 75 def interval(column) get("(max(#{literal(column)}) - min(#{literal(column)}))".lit) end |
#invert ⇒ Object
Inverts the current filter
dataset.filter(:category => 'software').invert.sql #=>
"SELECT * FROM items WHERE (category != 'software')"
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# File 'lib/sequel_core/dataset/sql.rb', line 309 def invert having, where = @opts[:having], @opts[:where] raise(Error, "No current filter") unless having || where o = {} o[:having] = SQL::BooleanExpression.invert(having) if having o[:where] = SQL::BooleanExpression.invert(where) if where clone(o) end |
#irregular_function_sql(f) ⇒ Object
SQL fragment specifying an Irregular (cast/extract) SQL function call
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# File 'lib/sequel_core/dataset/sql.rb', line 319 def irregular_function_sql(f) "#{f.f}(#{literal(f.arg1)} #{f.joiner} #{literal(f.arg2)})" end |
#join_clause_sql(jc) ⇒ Object
SQL fragment specifying a JOIN clause without ON or USING.
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# File 'lib/sequel_core/dataset/sql.rb', line 324 def join_clause_sql(jc) table = jc.table table_alias = jc.table_alias table_alias = nil if table == table_alias " #{join_type_sql(jc.join_type)} #{table_ref(table)}" \ "#{" AS #{quote_identifier(jc.table_alias)}" if table_alias}" end |
#join_on_clause_sql(jc) ⇒ Object
SQL fragment specifying a JOIN clause with ON.
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# File 'lib/sequel_core/dataset/sql.rb', line 333 def join_on_clause_sql(jc) "#{join_clause_sql(jc)} ON #{literal(filter_expr(jc.on))}" end |
#join_table(type, table, expr = nil, table_alias = nil, &block) ⇒ Object
Returns a joined dataset. Uses the following arguments:
-
type - The type of join to do (:inner, :left_outer, :right_outer, :full)
-
table - Depends on type:
-
Dataset - a subselect is performed with an alias of tN for some value of N
-
Model (or anything responding to :table_name) - table.table_name
-
String, Symbol: table
-
-
expr - specifies conditions, depends on type:
-
Hash, Array with all two pairs - Assumes key (1st arg) is column of joined table (unless already qualified), and value (2nd arg) is column of the last joined or primary table. To specify multiple conditions on a single joined table column, you must use an array. Uses a JOIN with an ON clause.
-
Array - If all members of the array are symbols, considers them as columns and uses a JOIN with a USING clause. Most databases will remove duplicate columns from the result set if this is used.
-
nil - If a block is not given, doesn’t use ON or USING, so the JOIN should be a NATURAL or CROSS join. If a block is given, uses a ON clause based on the block, see below.
-
Everything else - pretty much the same as a using the argument in a call to filter, so strings are considered literal, symbols specify boolean columns, and blockless filter expressions can be used. Uses a JOIN with an ON clause.
-
-
table_alias - the name of the table’s alias when joining, necessary for joining to the same table more than once. No alias is used by default.
-
block - The block argument should only be given if a JOIN with an ON clause is used, in which case it yields the table alias/name for the table currently being joined, the table alias/name for the last joined (or first table), and an array of previous SQL::JoinClause.
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# File 'lib/sequel_core/dataset/sql.rb', line 368 def join_table(type, table, expr=nil, table_alias=nil, &block) if Dataset === table if table_alias.nil? table_alias_num = (@opts[:num_dataset_sources] || 0) + 1 table_alias = "t#{table_alias_num}" end table_name = table_alias else table = table.table_name if table.respond_to?(:table_name) table_name = table_alias || table end join = if expr.nil? and !block_given? SQL::JoinClause.new(type, table, table_alias) elsif Array === expr and !expr.empty? and expr.all?{|x| Symbol === x} raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block_given? SQL::JoinUsingClause.new(expr, type, table, table_alias) else last_alias = @opts[:last_joined_table] || first_source if Hash === expr or (Array === expr and expr.all_two_pairs?) expr = expr.collect do |k, v| k = qualified_column_name(k, table_name) if k.is_a?(Symbol) v = qualified_column_name(v, last_alias) if v.is_a?(Symbol) [k,v] end end if block_given? expr2 = yield(table_name, last_alias, @opts[:join] || []) expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2 end SQL::JoinOnClause.new(expr, type, table, table_alias) end opts = {:join => (@opts[:join] || []) + [join], :last_joined_table => table_name} opts[:num_dataset_sources] = table_alias_num if table_alias_num clone(opts) end |
#join_using_clause_sql(jc) ⇒ Object
SQL fragment specifying a JOIN clause with USING.
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# File 'lib/sequel_core/dataset/sql.rb', line 338 def join_using_clause_sql(jc) "#{join_clause_sql(jc)} USING (#{column_list(jc.using)})" end |
#last(*args, &block) ⇒ Object
Reverses the order and then runs first. Note that this will not necessarily give you the last record in the dataset, unless you have an unambiguous order. If there is not currently an order for this dataset, raises an Error.
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# File 'lib/sequel_core/dataset/convenience.rb', line 83 def last(*args, &block) raise(Error, 'No order specified') unless @opts[:order] reverse.first(*args, &block) end |
#limit(l, o = nil) ⇒ Object
If given an integer, the dataset will contain only the first l results. If given a range, it will contain only those at offsets within that range. If a second argument is given, it is used as an offset.
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# File 'lib/sequel_core/dataset/sql.rb', line 409 def limit(l, o = nil) return from_self.limit(l, o) if @opts[:sql] if Range === l o = l.first l = l.interval + 1 end l = l.to_i raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1 opts = {:limit => l} if o o = o.to_i raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0 opts[:offset] = o end clone(opts) end |
#literal(v) ⇒ Object
Returns a literal representation of a value to be used as part of an SQL expression.
dataset.literal("abc'def\\") #=> "'abc''def\\\\'"
dataset.literal(:items__id) #=> "items.id"
dataset.literal([1, 2, 3]) => "(1, 2, 3)"
dataset.literal(DB[:items]) => "(SELECT * FROM items)"
dataset.literal(:x + 1 > :y) => "((x + 1) > y)"
If an unsupported object is given, an exception is raised.
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# File 'lib/sequel_core/dataset/sql.rb', line 437 def literal(v) case v when LiteralString v when String "'#{v.gsub(/\\/, "\\\\\\\\").gsub(/'/, "''")}'" when Integer, Float v.to_s when BigDecimal v.to_s("F") when NilClass NULL when TrueClass BOOL_TRUE when FalseClass BOOL_FALSE when Symbol symbol_to_column_ref(v) when ::Sequel::SQL::Expression v.to_s(self) when Array v.all_two_pairs? ? literal(v.sql_expr) : (v.empty? ? '(NULL)' : "(#{v.collect{|i| literal(i)}.join(COMMA_SEPARATOR)})") when Hash literal(v.sql_expr) when Time, DateTime v.strftime(TIMESTAMP_FORMAT) when Date v.strftime(DATE_FORMAT) when Dataset "(#{v.sql})" else raise Error, "can't express #{v.inspect} as a SQL literal" end end |
#map(column_name = nil, &block) ⇒ Object
Maps column values for each record in the dataset (if a column name is given), or performs the stock mapping functionality of Enumerable.
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# File 'lib/sequel_core/dataset/convenience.rb', line 90 def map(column_name = nil, &block) if column_name super() {|r| r[column_name]} else super(&block) end end |
#max(column) ⇒ Object
Returns the maximum value for the given column.
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# File 'lib/sequel_core/dataset/convenience.rb', line 99 def max(column) get(:max[column]) end |
#min(column) ⇒ Object
Returns the minimum value for the given column.
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# File 'lib/sequel_core/dataset/convenience.rb', line 104 def min(column) get(:min[column]) end |
#model_classes ⇒ Object
Returns the the model classes associated with the dataset as a hash. If the dataset is associated with a single model class, a key of nil is used. For datasets with polymorphic models, the keys are values of the polymorphic column and the values are the corresponding model classes to which they map.
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# File 'lib/sequel_core/dataset.rb', line 263 def model_classes @opts[:models] end |
#multi_insert(*args) ⇒ Object Also known as: import
Inserts multiple records into the associated table. This method can be to efficiently insert a large amounts of records into a table. Inserts are automatically wrapped in a transaction.
This method should be called with a columns array and an array of value arrays:
dataset.multi_insert([:x, :y], [[1, 2], [3, 4]])
This method can also be called with an array of hashes:
dataset.multi_insert({:x => 1}, {:x => 2})
Be aware that all hashes should have the same keys if you use this calling method, otherwise some columns could be missed or set to null instead of to default values.
The method also accepts a :slice or :commit_every option that specifies the number of records to insert per transaction. This is useful especially when inserting a large number of records, e.g.:
# this will commit every 50 records
dataset.multi_insert(lots_of_records, :slice => 50)
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# File 'lib/sequel_core/dataset/convenience.rb', line 130 def multi_insert(*args) if args.empty? return elsif args[0].is_a?(Array) && args[1].is_a?(Array) columns, values, opts = *args elsif args[0].is_a?(Array) && args[1].is_a?(Dataset) table = @opts[:from].first columns, dataset = *args sql = "INSERT INTO #{quote_identifier(table)} #{literal(columns)} VALUES #{literal(dataset)}" return @db.transaction {@db.execute sql} else # we assume that an array of hashes is given hashes, opts = *args return if hashes.empty? columns = hashes.first.keys # convert the hashes into arrays values = hashes.map {|h| columns.map {|c| h[c]}} end # make sure there's work to do return if columns.empty? || values.empty? slice_size = opts && (opts[:commit_every] || opts[:slice]) if slice_size values.each_slice(slice_size) do |slice| statements = multi_insert_sql(columns, slice) @db.transaction {statements.each {|st| @db.execute(st)}} end else statements = multi_insert_sql(columns, values) @db.transaction {statements.each {|st| @db.execute(st)}} end end |
#multi_insert_sql(columns, values) ⇒ Object
Returns an array of insert statements for inserting multiple records. This method is used by #multi_insert to format insert statements and expects a keys array and and an array of value arrays.
This method should be overridden by descendants if the support inserting multiple records in a single SQL statement.
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# File 'lib/sequel_core/dataset/sql.rb', line 478 def multi_insert_sql(columns, values) table = quote_identifier(@opts[:from].first) columns = literal(columns) values.map do |r| "INSERT INTO #{table} #{columns} VALUES #{literal(r)}" end end |
#naked ⇒ Object
Returns a naked dataset clone - i.e. a dataset that returns records as hashes rather than model objects.
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# File 'lib/sequel_core/dataset.rb', line 269 def naked clone.set_model(nil) end |
#or(*cond, &block) ⇒ Object
Adds an alternate filter to an existing filter using OR. If no filter exists an error is raised.
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# File 'lib/sequel_core/dataset/sql.rb', line 488 def or(*cond, &block) clause = (@opts[:having] ? :having : :where) cond = cond.first if cond.size == 1 if @opts[clause] clone(clause => SQL::BooleanExpression.new(:OR, @opts[clause], filter_expr(cond, &block))) else raise Error::NoExistingFilter, "No existing filter found." end end |
#order(*order) ⇒ Object Also known as: order_by
Returns a copy of the dataset with the order changed. If a nil is given the returned dataset has no order. This can accept multiple arguments of varying kinds, and even SQL functions.
ds.order(:name).sql #=> 'SELECT * FROM items ORDER BY name'
ds.order(:a, :b).sql #=> 'SELECT * FROM items ORDER BY a, b'
ds.order('a + b'.lit).sql #=> 'SELECT * FROM items ORDER BY a + b'
ds.order(:a + :b).sql #=> 'SELECT * FROM items ORDER BY (a + b)'
ds.order(:name.desc).sql #=> 'SELECT * FROM items ORDER BY name DESC'
ds.order(:name.asc).sql #=> 'SELECT * FROM items ORDER BY name ASC'
ds.order(:arr|1).sql #=> 'SELECT * FROM items ORDER BY arr[1]'
ds.order(nil).sql #=> 'SELECT * FROM items'
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# File 'lib/sequel_core/dataset/sql.rb', line 510 def order(*order) clone(:order => (order.compact.empty?) ? nil : order) end |
#order_more(*order) ⇒ Object
Returns a copy of the dataset with the order columns added to the existing order.
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# File 'lib/sequel_core/dataset/sql.rb', line 517 def order_more(*order) order(*((@opts[:order] || []) + order)) end |
#ordered_expression_sql(oe) ⇒ Object
SQL fragment for the ordered expression, used in the ORDER BY clause.
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# File 'lib/sequel_core/dataset/sql.rb', line 523 def ordered_expression_sql(oe) "#{literal(oe.expression)} #{oe.descending ? 'DESC' : 'ASC'}" end |
#paginate(page_no, page_size, record_count = nil) ⇒ Object
Returns a paginated dataset. The returned dataset is limited to the page size at the correct offset, and extended with the Pagination module. If a record count is not provided, does a count of total number of records for this dataset.
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# File 'lib/sequel_core/dataset/pagination.rb', line 7 def paginate(page_no, page_size, record_count=nil) raise(Error, "You cannot paginate a dataset that already has a limit") if @opts[:limit] paginated = limit(page_size, (page_no - 1) * page_size) paginated.extend(Pagination) paginated.set_pagination_info(page_no, page_size, record_count || count) end |
#polymorphic_key ⇒ Object
Returns the column name for the polymorphic key.
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# File 'lib/sequel_core/dataset.rb', line 274 def polymorphic_key @opts[:polymorphic_key] end |
#print(*cols) ⇒ Object
Pretty prints the records in the dataset as plain-text table.
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# File 'lib/sequel_core/dataset/convenience.rb', line 166 def print(*cols) Sequel::PrettyTable.print(naked.all, cols.empty? ? columns : cols) end |
#qualified_identifier_sql(qcr) ⇒ Object
SQL fragment for the qualifed identifier, specifying a table and a column (or schema and table).
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# File 'lib/sequel_core/dataset/sql.rb', line 529 def qualified_identifier_sql(qcr) "#{quote_identifier(qcr.table)}.#{quote_identifier(qcr.column)}" end |
#query(&block) ⇒ Object
Translates a query block into a dataset. Query blocks can be useful when expressing complex SELECT statements, e.g.:
dataset = DB[:items].query do
select :x, :y, :z
filter((:x > 1) & (:y > 2))
order :z.desc
end
Which is the same as:
dataset = DB[:items].select(:x, :y, :z).filter((:x > 1) & (:y > 2)).order(:z.desc)
Note that inside a call to query, you cannot call each, insert, update, or delete (or any method that calls those), or Sequel will raise an error.
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# File 'lib/sequel_core/dataset/query.rb', line 19 def query(&block) copy = clone({}) copy.extend(QueryBlockCopy) copy.instance_eval(&block) clone(copy.opts) end |
#quote_identifier(name) ⇒ Object Also known as: quote_column_ref
Adds quoting to identifiers (columns and tables). If identifiers are not being quoted, returns name as a string. If identifiers are being quoted quote the name with quoted_identifier.
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# File 'lib/sequel_core/dataset/sql.rb', line 536 def quote_identifier(name) quote_identifiers? ? quoted_identifier(name) : name.to_s end |
#quote_identifiers? ⇒ Boolean
Whether this dataset quotes identifiers.
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# File 'lib/sequel_core/dataset.rb', line 279 def quote_identifiers? @quote_identifiers end |
#quoted_identifier(name) ⇒ Object
This method quotes the given name with the SQL standard double quote. It uppercases the name given to conform with the SQL standard. This should be overridden by subclasses to provide quoting not matching the SQL standard, such as backtick (used by MySQL and SQLite), or where lowercase is the default for unquoted identifiers (PostgreSQL).
If you are using a database such as Oracle that defaults to uppercase but you are using lower case identifiers, you should override this method to not upcase the name for those identifiers.
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# File 'lib/sequel_core/dataset/sql.rb', line 550 def quoted_identifier(name) "\"#{name.to_s.upcase}\"" end |
#range(column) ⇒ Object
Returns a Range object made from the minimum and maximum values for the given column.
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# File 'lib/sequel_core/dataset/convenience.rb', line 172 def range(column) if r = select(:min[column].as(:v1), :max[column].as(:v2)).first (r[:v1]..r[:v2]) end end |
#reverse_order(*order) ⇒ Object Also known as: reverse
Returns a copy of the dataset with the order reversed. If no order is given, the existing order is inverted.
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# File 'lib/sequel_core/dataset/sql.rb', line 556 def reverse_order(*order) order(*invert_order(order.empty? ? @opts[:order] : order)) end |
#select(*columns) ⇒ Object
Returns a copy of the dataset with the columns selected changed to the given columns.
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# File 'lib/sequel_core/dataset/sql.rb', line 563 def select(*columns) clone(:select => columns) end |
#select_all ⇒ Object
Returns a copy of the dataset selecting the wildcard.
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# File 'lib/sequel_core/dataset/sql.rb', line 568 def select_all clone(:select => nil) end |
#select_more(*columns) ⇒ Object
Returns a copy of the dataset with the given columns added to the existing selected columns.
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# File 'lib/sequel_core/dataset/sql.rb', line 574 def select_more(*columns) select(*((@opts[:select] || []) + columns)) end |
#select_sql(opts = nil) ⇒ Object Also known as: sql
Formats a SELECT statement using the given options and the dataset options.
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# File 'lib/sequel_core/dataset/sql.rb', line 580 def select_sql(opts = nil) opts = opts ? @opts.merge(opts) : @opts if sql = opts[:sql] return sql end columns = opts[:select] select_columns = columns ? column_list(columns) : WILDCARD if distinct = opts[:distinct] distinct_clause = distinct.empty? ? "DISTINCT" : "DISTINCT ON (#{column_list(distinct)})" sql = "SELECT #{distinct_clause} #{select_columns}" else sql = "SELECT #{select_columns}" end if opts[:from] sql << " FROM #{source_list(opts[:from])}" end if join = opts[:join] join.each{|j| sql << literal(j)} end if where = opts[:where] sql << " WHERE #{literal(where)}" end if group = opts[:group] sql << " GROUP BY #{column_list(group)}" end if having = opts[:having] sql << " HAVING #{literal(having)}" end if order = opts[:order] sql << " ORDER BY #{column_list(order)}" end if limit = opts[:limit] sql << " LIMIT #{limit}" if offset = opts[:offset] sql << " OFFSET #{offset}" end end if union = opts[:union] sql << (opts[:union_all] ? \ " UNION ALL #{union.sql}" : " UNION #{union.sql}") elsif intersect = opts[:intersect] sql << (opts[:intersect_all] ? \ " INTERSECT ALL #{intersect.sql}" : " INTERSECT #{intersect.sql}") elsif except = opts[:except] sql << (opts[:except_all] ? \ " EXCEPT ALL #{except.sql}" : " EXCEPT #{except.sql}") end sql end |
#set(*args, &block) ⇒ Object
Alias for set, but not aliased directly so subclasses don’t have to override both methods.
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# File 'lib/sequel_core/dataset.rb', line 285 def set(*args, &block) update(*args, &block) end |
#set_graph_aliases(graph_aliases) ⇒ Object
This allows you to manually specify the graph aliases to use when using graph. You can use it to only select certain columns, and have those columns mapped to specific aliases in the result set. This is the equivalent of .select for a graphed dataset, and must be used instead of .select whenever graphing is used. Example:
DB[:artists].graph(:albums, :artist_id=>:id).set_graph_aliases(:artist_name=>[:artists, :name], :album_name=>[:albums, :name]).first
=> {:artists=>{:name=>artists.name}, :albums=>{:name=>albums.name}}
Arguments:
-
graph_aliases - Should be a hash with keys being symbols of column aliases, and values being arrays with two symbol elements. The first element of the array should be the table alias, and the second should be the actual column name.
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# File 'lib/sequel_core/object_graph.rb', line 160 def set_graph_aliases(graph_aliases) ds = select(*graph_aliases.collect{|col_alias, tc| :"#{tc[0]}__#{tc[1]}#{"___#{col_alias}" unless tc[1] == col_alias}"}) ds.opts[:graph_aliases]=graph_aliases ds end |
#set_model(key, *args) ⇒ Object
Associates or disassociates the dataset with a model(s). If nil is specified, the dataset is turned into a naked dataset and returns records as hashes. If a model class specified, the dataset is modified to return records as instances of the model class, e.g:
class MyModel
def initialize(values)
@values = values
...
end
end
dataset.set_model(MyModel)
You can also provide additional arguments to be passed to the model’s initialize method:
class MyModel
def initialize(values, options)
@values = values
...
end
end
dataset.set_model(MyModel, :allow_delete => false)
The dataset can be made polymorphic by specifying a column name as the polymorphic key and a hash mapping column values to model classes.
dataset.set_model(:kind, {1 => Person, 2 => Business})
You can also set a default model class to fall back on by specifying a class corresponding to nil:
dataset.set_model(:kind, {nil => DefaultClass, 1 => Person, 2 => Business})
To make sure that there is always a default model class, the hash provided should have a default value. To make the dataset map string values to model classes, and keep a good default, try:
dataset.set_model(:kind, Hash.new{|h,k| h[k] = (k.constantize rescue DefaultClass)})
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# File 'lib/sequel_core/dataset.rb', line 330 def set_model(key, *args) # This code is more verbose then necessary for performance reasons case key when nil # set_model(nil) => no argument provided, so the dataset is denuded @opts.merge!(:naked => true, :models => nil, :polymorphic_key => nil) self.row_proc = nil when Class # isomorphic model @opts.merge!(:naked => nil, :models => {nil => key}, :polymorphic_key => nil) if key.respond_to?(:load) # the class has a values setter method, so we use it self.row_proc = proc{|h| key.load(h, *args)} else # otherwise we just pass the hash to the constructor self.row_proc = proc{|h| key.new(h, *args)} end when Symbol # polymorphic model hash = args.shift || raise(ArgumentError, "No class hash supplied for polymorphic model") @opts.merge!(:naked => true, :models => hash, :polymorphic_key => key) if (hash.empty? ? (hash[nil] rescue nil) : hash.values.first).respond_to?(:load) # the class has a values setter method, so we use it self.row_proc = proc do |h| c = hash[h[key]] || hash[nil] || \ raise(Error, "No matching model class for record (#{polymorphic_key} => #{h[polymorphic_key].inspect})") c.load(h, *args) end else # otherwise we just pass the hash to the constructor self.row_proc = proc do |h| c = hash[h[key]] || hash[nil] || \ raise(Error, "No matching model class for record (#{polymorphic_key} => #{h[polymorphic_key].inspect})") c.new(h, *args) end end else raise ArgumentError, "Invalid model specified" end self end |
#single_record(opts = nil) ⇒ Object
Returns the first record in the dataset.
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# File 'lib/sequel_core/dataset/convenience.rb', line 179 def single_record(opts = nil) each((opts||{}).merge(:limit=>1)){|r| return r} nil end |
#single_value(opts = nil) ⇒ Object
Returns the first value of the first record in the dataset. Returns nil if dataset is empty.
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# File 'lib/sequel_core/dataset/convenience.rb', line 186 def single_value(opts = nil) if r = naked.single_record(opts) r.values.first end end |
#subscript_sql(s) ⇒ Object
SQL fragment for specifying subscripts (SQL arrays)
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# File 'lib/sequel_core/dataset/sql.rb', line 644 def subscript_sql(s) "#{s.f}[#{s.sub.join(COMMA_SEPARATOR)}]" end |
#sum(column) ⇒ Object
Returns the sum for the given column.
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# File 'lib/sequel_core/dataset/convenience.rb', line 193 def sum(column) get(:sum[column]) end |
#symbol_to_column_ref(sym) ⇒ Object
Converts a symbol into a column name. This method supports underscore notation in order to express qualified (two underscores) and aliased (three underscores) columns:
ds = DB[:items]
:abc.to_column_ref(ds) #=> "abc"
:abc___a.to_column_ref(ds) #=> "abc AS a"
:items__abc.to_column_ref(ds) #=> "items.abc"
:items__abc___a.to_column_ref(ds) #=> "items.abc AS a"
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# File 'lib/sequel_core/dataset/sql.rb', line 658 def symbol_to_column_ref(sym) c_table, column, c_alias = split_symbol(sym) "#{"#{quote_identifier(c_table)}." if c_table}#{quote_identifier(column)}#{" AS #{quote_identifier(c_alias)}" if c_alias}" end |
#table_exists? ⇒ Boolean
Returns true if the table exists. Will raise an error if the dataset has fixed SQL or selects from another dataset or more than one table.
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# File 'lib/sequel_core/dataset/convenience.rb', line 200 def table_exists? if @opts[:sql] raise Sequel::Error, "this dataset has fixed SQL" end if @opts[:from].size != 1 raise Sequel::Error, "this dataset selects from multiple sources" end t = @opts[:from].first if t.is_a?(Dataset) raise Sequel::Error, "this dataset selects from a sub query" end @db.table_exists?(t.to_sym) end |
#to_csv(include_column_titles = true) ⇒ Object
Returns a string in CSV format containing the dataset records. By default the CSV representation includes the column titles in the first line. You can turn that off by passing false as the include_column_titles argument.
This does not use a CSV library or handle quoting of values in any way. If any values in any of the rows could include commas or line endings, you probably shouldn’t use this.
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# File 'lib/sequel_core/dataset/convenience.rb', line 225 def to_csv(include_column_titles = true) n = naked cols = n.columns csv = '' csv << "#{cols.join(COMMA_SEPARATOR)}\r\n" if include_column_titles n.each{|r| csv << "#{cols.collect{|c| r[c]}.join(COMMA_SEPARATOR)}\r\n"} csv end |
#to_hash(key_column, value_column = nil) ⇒ Object
Returns a hash with one column used as key and another used as value. If rows have duplicate values for the key column, the latter row(s) will overwrite the value of the previous row(s). If the value_column is not given or nil, uses the entire hash as the value.
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# File 'lib/sequel_core/dataset/convenience.rb', line 238 def to_hash(key_column, value_column = nil) inject({}) do |m, r| m[r[key_column]] = value_column ? r[value_column] : r m end end |
#transform(t) ⇒ Object
Sets a value transform which is used to convert values loaded and saved to/from the database. The transform should be supplied as a hash. Each value in the hash should be an array containing two proc objects - one for transforming loaded values, and one for transforming saved values. The following example demonstrates how to store Ruby objects in a dataset using Marshal serialization:
dataset.transform(:obj => [
proc {|v| Marshal.load(v)},
proc {|v| Marshal.dump(v)}
])
dataset.insert_sql(:obj => 1234) #=>
"INSERT INTO items (obj) VALUES ('\004\bi\002\322\004')"
Another form of using transform is by specifying stock transforms:
dataset.transform(:obj => :marshal)
The currently supported stock transforms are :marshal and :yaml.
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# File 'lib/sequel_core/dataset.rb', line 391 def transform(t) @transform = t t.each do |k, v| case v when Array if (v.size != 2) || !v.first.is_a?(Proc) && !v.last.is_a?(Proc) raise Error::InvalidTransform, "Invalid transform specified" end else unless v = STOCK_TRANSFORMS[v] raise Error::InvalidTransform, "Invalid transform specified" else t[k] = v end end end self end |
#transform_load(r) ⇒ Object
Applies the value transform for data loaded from the database.
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# File 'lib/sequel_core/dataset.rb', line 411 def transform_load(r) r.inject({}) do |m, kv| k, v = *kv m[k] = (tt = @transform[k]) ? tt[0][v] : v m end end |
#transform_save(r) ⇒ Object
Applies the value transform for data saved to the database.
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# File 'lib/sequel_core/dataset.rb', line 420 def transform_save(r) r.inject({}) do |m, kv| k, v = *kv m[k] = (tt = @transform[k]) ? tt[1][v] : v m end end |
#unfiltered ⇒ Object
Returns a copy of the dataset with no filters (HAVING or WHERE clause) applied.
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# File 'lib/sequel_core/dataset/sql.rb', line 664 def unfiltered clone(:where => nil, :having => nil) end |
#union(dataset, all = false) ⇒ Object
Adds a UNION clause using a second dataset object. If all is true the clause used is UNION ALL, which may return duplicate rows.
DB[:items].union(DB[:other_items]).sql
#=> "SELECT * FROM items UNION SELECT * FROM other_items"
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# File 'lib/sequel_core/dataset/sql.rb', line 673 def union(dataset, all = false) clone(:union => dataset, :union_all => all) end |
#uniq(*args) ⇒ Object Also known as: distinct
Returns a copy of the dataset with the distinct option.
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# File 'lib/sequel_core/dataset/sql.rb', line 678 def uniq(*args) clone(:distinct => args) end |
#unordered ⇒ Object
Returns a copy of the dataset with no order.
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# File 'lib/sequel_core/dataset/sql.rb', line 684 def unordered order(nil) end |
#update(values, opts = nil) ⇒ Object
Updates values for the dataset. Adapters should override this method.
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# File 'lib/sequel_core/dataset.rb', line 429 def update(values, opts = nil) raise NotImplementedError, NOTIMPL_MSG end |
#update_sql(values = {}, opts = nil, &block) ⇒ Object
Formats an UPDATE statement using the given values.
dataset.update_sql(:price => 100, :category => 'software') #=>
"UPDATE items SET price = 100, category = 'software'"
Accepts a block, but such usage is discouraged.
Raises an error if the dataset is grouped or includes more than one table.
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# File 'lib/sequel_core/dataset/sql.rb', line 697 def update_sql(values = {}, opts = nil, &block) opts = opts ? @opts.merge(opts) : @opts if opts[:group] raise Error::InvalidOperation, "A grouped dataset cannot be updated" elsif (opts[:from].size > 1) or opts[:join] raise Error::InvalidOperation, "A joined dataset cannot be updated" end sql = "UPDATE #{source_list(@opts[:from])} SET " if block sql << block.to_sql(self, :comma_separated => true) else set = if values.is_a?(Hash) # get values from hash values = transform_save(values) if @transform values.map do |k, v| # convert string key into symbol k = k.to_sym if String === k "#{literal(k)} = #{literal(v)}" end.join(COMMA_SEPARATOR) else # copy values verbatim values end sql << set end if where = opts[:where] sql << " WHERE #{literal(where)}" end sql end |