Module: Sequel::Model::ClassMethods

Defined in:
lib/sequel/lib/sequel/model/base.rb,
lib/sequel/lib/sequel/model/plugins.rb

Overview

Class methods for Sequel::Model that implement basic model functionality.

  • All of the method names in Model::DATASET_METHODS have class methods created that call the Model's dataset with the method of the same name with the given arguments.

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#allowed_columnsObject (readonly)

Which columns should be the only columns allowed in a call to set (default: not set, so all columns not otherwise restricted).


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# File 'lib/sequel/lib/sequel/model/base.rb', line 15

def allowed_columns
  @allowed_columns
end

#dataset_method_modulesObject (readonly)

Array of modules that extend this model's dataset. Stored so that if the model's dataset is changed, it will be extended with all of these modules.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 20

def dataset_method_modules
  @dataset_method_modules
end

#dataset_methodsObject (readonly)

Hash of dataset methods with method name keys and proc values that are stored so when the dataset changes, methods defined with def_dataset_method will be applied to the new dataset.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 25

def dataset_methods
  @dataset_methods
end

#pluginsObject (readonly)

Array of plugins loaded by this class


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# File 'lib/sequel/lib/sequel/model/plugins.rb', line 58

def plugins
  @plugins
end

#primary_keyObject (readonly)

The primary key for the class. Sequel can determine this automatically for many databases, but not all, so you may need to set it manually. If not determined automatically, the default is :id.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 30

def primary_key
  @primary_key
end

#raise_on_save_failureObject

Whether to raise an error instead of returning nil on a failure to save/create/save_changes/etc due to a validation failure or a before_* hook returning false.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 35

def raise_on_save_failure
  @raise_on_save_failure
end

#raise_on_typecast_failureObject

Whether to raise an error when unable to typecast data for a column (default: true). This should be set to false if you want to use validations to display nice error messages to the user (e.g. most web applications). You can use the validates_not_string validations (from either the validation_helpers or validation_class_methods standard plugins) in connection with option to check for typecast failures for columns that aren't blobs or strings.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 44

def raise_on_typecast_failure
  @raise_on_typecast_failure
end

#restricted_columnsObject (readonly)

Which columns are specifically restricted in a call to set/update/new/etc. (default: not set). Some columns are restricted regardless of this setting, such as the primary key column and columns in Model::RESTRICTED_SETTER_METHODS.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 49

def restricted_columns
  @restricted_columns
end

#simple_pkObject (readonly)

Should be the literal primary key column name if this Model's table has a simple primary key, or nil if the model has a compound primary key or no primary key.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 53

def simple_pk
  @simple_pk
end

#simple_tableObject (readonly)

Should be the literal table name if this Model's dataset is a simple table (no select, order, join, etc.), or nil otherwise. This and simple_pk are used for an optimization in Model.[].


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# File 'lib/sequel/lib/sequel/model/base.rb', line 57

def simple_table
  @simple_table
end

#strict_param_settingObject

Whether new/set/update and their variants should raise an error if an invalid key is used. A key is invalid if no setter method exists for that key or the access to the setter method is restricted (e.g. due to it being a primary key field). If set to false, silently skip any key where the setter method doesn't exist or access to it is restricted.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 64

def strict_param_setting
  @strict_param_setting
end

#typecast_empty_string_to_nilObject

Whether to typecast the empty string ('') to nil for columns that are not string or blob. In most cases the empty string would be the way to specify a NULL SQL value in string form (nil.to_s == ''), and an empty string would not usually be typecast correctly for other types, so the default is true.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 71

def typecast_empty_string_to_nil
  @typecast_empty_string_to_nil
end

#typecast_on_assignmentObject

Whether to typecast attribute values on assignment (default: true). If set to false, no typecasting is done, so it will be left up to the database to typecast the value correctly.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 76

def typecast_on_assignment
  @typecast_on_assignment
end

#use_transactionsObject

Whether to use a transaction by default when saving/deleting records (default: true). If you are sending database queries in before_* or after_* hooks, you shouldn't change the default setting without a good reason.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 81

def use_transactions
  @use_transactions
end

Instance Method Details

#[](*args) ⇒ Object

Returns the first record from the database matching the conditions. If a hash is given, it is used as the conditions. If another object is given, it finds the first record whose primary key(s) match the given argument(s).


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# File 'lib/sequel/lib/sequel/model/base.rb', line 87

def [](*args)
  args = args.first if (args.size == 1)
  args.is_a?(Hash) ? dataset[args] : primary_key_lookup(args)
end

#columnsObject

Returns the columns in the result set in their original order. Generally, this will use the columns determined via the database schema, but in certain cases (e.g. models that are based on a joined dataset) it will use Dataset#columns to find the columns, which may be empty if the Dataset has no records.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 97

def columns
  @columns || set_columns(dataset.naked.columns)
end

#create(values = {}, &block) ⇒ Object

Creates instance using new with the given values and block, and saves it.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 102

def create(values = {}, &block)
  new(values, &block).save
end

#datasetObject

Returns the dataset associated with the Model class. Raises an error if there is no associated dataset for this class.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 108

def dataset
  @dataset || raise(Error, "No dataset associated with #{self}")
end

#dbObject

Returns the database associated with the Model class. If this model doesn't have a database associated with it, assumes the superclass's database, or the first object in Sequel::DATABASES. If no Sequel::Database object has been created, raises an error.

Raises:


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# File 'lib/sequel/lib/sequel/model/base.rb', line 117

def db
  return @db if @db
  @db = self == Model ? DATABASES.first : superclass.db
  raise(Error, "No database associated with #{self}") unless @db
  @db
end

#db=(db) ⇒ Object

Sets the database associated with the Model class. If the model has an associated dataset, sets the model's dataset to a dataset on the new database with the same options used by the current dataset.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 128

def db=(db)
  @db = db
  set_dataset(db.dataset(@dataset.opts)) if @dataset
end

#db_schemaObject

Returns the cached schema information if available or gets it from the database.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 135

def db_schema
  @db_schema ||= get_db_schema
end

#def_dataset_method(*args, &block) ⇒ Object

If a block is given, define a method on the dataset (if the model has an associated dataset) with the given argument name using the given block as well as a method on the model that calls the dataset method. Stores the method name and block so that it can be reapplied if the model's dataset changes.

If a block is not given, define a method on the model for each argument that calls the dataset method of the same argument name.

Raises:


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# File 'lib/sequel/lib/sequel/model/base.rb', line 146

def def_dataset_method(*args, &block)
  raise(Error, "No arguments given") if args.empty?
  if block_given?
    raise(Error, "Defining a dataset method using a block requires only one argument") if args.length > 1
    meth = args.first
    @dataset_methods[meth] = block
    dataset.meta_def(meth, &block) if @dataset
  end
  args.each{|arg| instance_eval("def #{arg}(*args, &block); dataset.#{arg}(*args, &block) end", __FILE__, __LINE__) unless respond_to?(arg)}
end

#find(*args, &block) ⇒ Object

Finds a single record according to the supplied filter, e.g.:

Ticket.find :author => 'Sharon' # => record

You are encouraged to use Model.[] or Model.first instead of this method.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 162

def find(*args, &block)
  filter(*args, &block).first
end

#find_or_create(cond) ⇒ Object

Like find but invokes create with given conditions when record does not exist.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 168

def find_or_create(cond)
  find(cond) || create(cond)
end

#implicit_table_nameObject

Returns the implicit table name for the model class.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 199

def implicit_table_name
  pluralize(underscore(demodulize(name))).to_sym
end

#inherited(subclass) ⇒ Object

If possible, set the dataset for the model subclass as soon as it is created. Also, make sure the inherited class instance variables are copied into the subclass.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 175

def inherited(subclass)
  ivs = subclass.instance_variables.collect{|x| x.to_s}
  EMPTY_INSTANCE_VARIABLES.each{|iv| subclass.instance_variable_set(iv, nil) unless ivs.include?(iv.to_s)}
  INHERITED_INSTANCE_VARIABLES.each do |iv, dup|
    next if ivs.include?(iv.to_s)
    sup_class_value = instance_variable_get(iv)
    sup_class_value = sup_class_value.dup if dup == :dup && sup_class_value
    subclass.instance_variable_set(iv, sup_class_value)
  end
  unless ivs.include?("@dataset")
    db
    begin
      if self == Model || !@dataset
        subclass.set_dataset(subclass.implicit_table_name) unless subclass.name.empty?
      elsif @dataset
        subclass.set_dataset(@dataset.clone, :inherited=>true)
      end
    rescue
      nil
    end
  end
end

#load(values) ⇒ Object

Initializes a model instance as an existing record. This constructor is used by Sequel to initialize model instances when fetching records. load requires that values be a hash where all keys are symbols. It probably should not be used by external code.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 207

def load(values)
  new(values, true)
end

#no_primary_keyObject

Mark the model as not having a primary key. Not having a primary key can cause issues, among which is that you won't be able to update records.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 213

def no_primary_key
  @simple_pk = @primary_key = nil
end

#primary_key_hash(value) ⇒ Object

Returns primary key attribute hash. If using a composite primary key value such be an array with values for each primary key in the correct order. For a standard primary key, value should be an object with a compatible type for the key. If the model does not have a primary key, raises an Error.

Raises:


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# File 'lib/sequel/lib/sequel/model/base.rb', line 222

def primary_key_hash(value)
  raise(Error, "#{self} does not have a primary key") unless key = @primary_key
  case key
  when Array
    hash = {}
    key.each_with_index{|k,i| hash[k] = value[i]}
    hash
  else
    {key => value}
  end
end

#restrict_primary_keyObject

Restrict the setting of the primary key(s) inside new/set/update. Because this is the default, this only make sense to use in a subclass where the parent class has used unrestrict_primary_key.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 237

def restrict_primary_key
  @restrict_primary_key = true
end

#restrict_primary_key?Boolean

Whether or not setting the primary key inside new/set/update is restricted, true by default.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 243

def restrict_primary_key?
  @restrict_primary_key
end

#set_allowed_columns(*cols) ⇒ Object

Set the columns to allow in new/set/update. Using this means that any columns not listed here will not be modified. If you have any virtual setter methods (methods that end in =) that you want to be used in new/set/update, they need to be listed here as well (without the =).

It may be better to use (set|update)_only instead of this in places where only certain columns may be allowed.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 254

def set_allowed_columns(*cols)
  @allowed_columns = cols
end

#set_dataset(ds, opts = {}) ⇒ Object Also known as: dataset=

Sets the dataset associated with the Model class. ds can be a Symbol (specifying a table name in the current database), or a Dataset. If a dataset is used, the model's database is changed to the given dataset. If a symbol is used, a dataset is created from the current database with the table name given. Other arguments raise an Error. Returns self.

This changes the row_proc of the given dataset to return model objects, extends the dataset with the dataset_method_modules, and defines methods on the dataset using the dataset_methods. It also attempts to determine the database schema for the model, based on the given dataset.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 270

def set_dataset(ds, opts={})
  inherited = opts[:inherited]
  @dataset = case ds
  when Symbol
    @simple_table = db.literal(ds)
    db[ds]
  when Dataset
    @simple_table = nil
    @db = ds.db
    ds
  else
    raise(Error, "Model.set_dataset takes a Symbol or a Sequel::Dataset")
  end
  @dataset.row_proc = Proc.new{|r| load(r)}
  if inherited
    @simple_table = superclass.simple_table
    @columns = @dataset.columns rescue nil
  else
    @dataset_method_modules.each{|m| @dataset.extend(m)} if @dataset_method_modules
    @dataset_methods.each{|meth, block| @dataset.meta_def(meth, &block)} if @dataset_methods
  end
  @dataset.model = self if @dataset.respond_to?(:model=)
  begin
    @db_schema = (inherited ? superclass.db_schema : get_db_schema)
  rescue Sequel::DatabaseConnectionError
    raise
  rescue
    nil
  end
  self
end

#set_primary_key(*key) ⇒ Object

Sets the primary key for this model. You can use either a regular or a composite primary key.

Example:

class Tagging < Sequel::Model
  # composite key
  set_primary_key :taggable_id, :tag_id
end

class Person < Sequel::Model
  # regular key
  set_primary_key :person_id
end

You can set it to nil to not have a primary key, but that cause certain things not to work, see no_primary_key.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 319

def set_primary_key(*key)
  key = key.flatten
  @simple_pk = key.length == 1 ? db.literal(key.first) : nil 
  @primary_key = (key.length == 1) ? key[0] : key
end

#set_restricted_columns(*cols) ⇒ Object

Set the columns to restrict in new/set/update. Using this means that attempts to call setter methods for the columns listed here will cause an exception or be silently skipped (based on the strict_param_setting setting. If you have any virtual # setter methods (methods that end in =) that you want not to be used in new/set/update, they need to be listed here as well (without the =).

It may be better to use (set|update)_except instead of this in places where only certain columns may be allowed.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 333

def set_restricted_columns(*cols)
  @restricted_columns = cols
end

#subset(name, *args, &block) ⇒ Object

Defines a method that returns a filtered dataset. Subsets create dataset methods, so they can be chained for scoping. For example:

Topic.subset(:joes, :username.like('%joe%'))
Topic.subset(:popular){|o| o.num_posts > 100}
Topic.subset(:recent){|o| o.created_on > Date.today - 7}

Allows you to do:

Topic.joes.recent.popular

to get topics with a username that includes joe that have more than 100 posts and were created less than 7 days ago.

Both the args given and the block are passed to Dataset#filter.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 354

def subset(name, *args, &block)
  def_dataset_method(name){filter(*args, &block)}
end

#table_nameObject

Returns name of primary table for the dataset.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 359

def table_name
  dataset.opts[:from].first
end

#unrestrict_primary_keyObject

Allow the setting of the primary key(s) inside new/set/update.


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# File 'lib/sequel/lib/sequel/model/base.rb', line 364

def unrestrict_primary_key
  @restrict_primary_key = false
end