Module: Sequel::Model::ClassMethods

Included in:
Sequel::Model
Defined in:
lib/sequel/model/base.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_columns ⇒ Object (readonly)

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



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

def allowed_columns
  @allowed_columns
end

#dataset_method_modules ⇒ Object (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/model/base.rb', line 20

def dataset_method_modules
  @dataset_method_modules
end

#dataset_methods ⇒ Object (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/model/base.rb', line 25

def dataset_methods
  @dataset_methods
end

#plugins ⇒ Object (readonly)

Array of plugin modules loaded by this class

Sequel::Model.plugins
# => [Sequel::Model, Sequel::Model::Associations]



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# File 'lib/sequel/model/base.rb', line 31

def plugins
  @plugins
end

#primary_key ⇒ Object (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/model/base.rb', line 36

def primary_key
  @primary_key
end

#raise_on_save_failure ⇒ Object

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/model/base.rb', line 41

def raise_on_save_failure
  @raise_on_save_failure
end

#raise_on_typecast_failure ⇒ Object

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/model/base.rb', line 50

def raise_on_typecast_failure
  @raise_on_typecast_failure
end

#require_modification ⇒ Object

Whether to raise an error if an UPDATE or DELETE query related to a model instance does not modify exactly 1 row. If set to false, Sequel will not check the number of rows modified (default: true).



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# File 'lib/sequel/model/base.rb', line 55

def require_modification
  @require_modification
end

#restricted_columns ⇒ Object (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/model/base.rb', line 60

def restricted_columns
  @restricted_columns
end

#simple_pk ⇒ Object (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/model/base.rb', line 64

def simple_pk
  @simple_pk
end

#simple_table ⇒ Object (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/model/base.rb', line 68

def simple_table
  @simple_table
end

#strict_param_setting ⇒ Object

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/model/base.rb', line 75

def strict_param_setting
  @strict_param_setting
end

#typecast_empty_string_to_nil ⇒ Object

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/model/base.rb', line 82

def typecast_empty_string_to_nil
  @typecast_empty_string_to_nil
end

#typecast_on_assignment ⇒ Object

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/model/base.rb', line 87

def typecast_on_assignment
  @typecast_on_assignment
end

#use_transactions ⇒ Object

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/model/base.rb', line 92

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). If no object is returned by the dataset, returns nil.

Artist[1] # SELECT * FROM artists WHERE id = 1
# => #<Artist {:id=>1, ...}>

Artist[:name=>'Bob'] # SELECT * FROM artists WHERE (name = 'Bob') LIMIT 1
# => #<Artist {:name=>'Bob', ...}>



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# File 'lib/sequel/model/base.rb', line 104

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

#clear_setter_methods_cache ⇒ Object

Clear the setter_methods cache



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# File 'lib/sequel/model/base.rb', line 110

def clear_setter_methods_cache
  @setter_methods = nil
end

#columns ⇒ Object

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.

Artist.columns
# => [:id, :name]



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# File 'lib/sequel/model/base.rb', line 121

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.

Artist.create(:name=>'Bob')
# INSERT INTO artists (name) VALUES ('Bob')

Artist.create do |a|
  a.name = 'Jim'
end # INSERT INTO artists (name) VALUES ('Jim')



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# File 'lib/sequel/model/base.rb', line 133

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

#dataset ⇒ Object

Returns the dataset associated with the Model class. Raises an Error if there is no associated dataset for this class. In most cases, you don’t need to call this directly, as Model proxies many dataset methods to the underlying dataset.

Artist.dataset.all # SELECT * FROM artists



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# File 'lib/sequel/model/base.rb', line 143

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

#dataset=(ds) ⇒ Object

Alias of set_dataset



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# File 'lib/sequel/model/base.rb', line 148

def dataset=(ds)
  set_dataset(ds)
end

#db ⇒ Object

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.

Artist.db.transaction do # BEGIN
  Artist.create(:name=>'Bob')
  # INSERT INTO artists (name) VALUES ('Bob')
end # COMMIT

Raises:



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

def db
  return @db if @db
  @db = self == Model ? DATABASES.first : superclass.db
  raise(Error, "No database associated with #{self}: have you called Sequel.connect or #{self}.db= ?") 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. This can be used directly on Sequel::Model to set the default database to be used by subclasses, or to override the database used for specific models:

Sequel::Model.db = DB1
Artist.db = DB2



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# File 'lib/sequel/model/base.rb', line 179

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

#db_schema ⇒ Object

Returns the cached schema information if available or gets it from the database. This is a hash where keys are column symbols and values are hashes of information related to the column. See Database#schema.

Artist.db_schema
# {:id=>{:type=>:integer, :primary_key=>true, ...},
#  :name=>{:type=>:string, :primary_key=>false, ...}}



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# File 'lib/sequel/model/base.rb', line 192

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 currently has an dataset) with the given argument name using the given block. Also define a class 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, just define a class method on the model for each argument that calls the dataset method of the same argument name.

# Add new dataset method and class method that calls it
Artist.def_dataset_method(:by_name){order(:name)}
Artist.filter(:name.like('A%')).by_name
Artist.by_name.filter(:name.like('A%'))

# Just add a class method that calls an existing dataset method
Artist.def_dataset_method(:server!)
Artist.server!(:server1)

Raises:



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# File 'lib/sequel/model/base.rb', line 212

def def_dataset_method(*args, &block)
  raise(Error, "No arguments given") if args.empty?
  if block
    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. You are encouraged to use Model.[] or Model.first instead of this method.

Artist.find(:name=>'Bob')
# SELECT * FROM artists WHERE (name = 'Bob') LIMIT 1

Artist.find{name > 'M'}
# SELECT * FROM artists WHERE (name > 'M') LIMIT 1



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# File 'lib/sequel/model/base.rb', line 231

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

#find_or_create(cond, &block) ⇒ Object

Like find but invokes create with given conditions when record does not exist. Unlike find in that the block used in this method is not passed to find, but instead is passed to create only if find does not return an object.

Artist.find_or_create(:name=>'Bob')
# SELECT * FROM artists WHERE (name = 'Bob') LIMIT 1
# INSERT INTO artists (name) VALUES ('Bob')

Artist.find_or_create(:name=>'Jim'){|a| a.hometown = 'Sactown'}
# SELECT * FROM artists WHERE (name = 'Jim') LIMIT 1
# INSERT INTO artists (name, hometown) VALUES ('Jim', 'Sactown')



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# File 'lib/sequel/model/base.rb', line 247

def find_or_create(cond, &block)
  find(cond) || create(cond, &block)
end

#implicit_table_name ⇒ Object

Returns the implicit table name for the model class, which is the demodulized, underscored, pluralized name of the class.

Artist.implicit_table_name # => :artists
Foo::ArtistAlias.implicit_table_name # => :artist_aliases



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# File 'lib/sequel/model/base.rb', line 290

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.

Sequel queries the database to get schema information as soon as a model class is created:

class Artist < Sequel::Model # Causes schema query
end



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# File 'lib/sequel/model/base.rb', line 260

def inherited(subclass)
  super
  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
        n = subclass.name
        subclass.set_dataset(subclass.implicit_table_name) unless n.nil? || n.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/model/base.rb', line 298

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

#method_added(meth) ⇒ Object

Clear the setter_methods cache when a setter method is added



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# File 'lib/sequel/model/base.rb', line 303

def method_added(meth)
  clear_setter_methods_cache if meth.to_s =~ SETTER_METHOD_REGEXP
  super
end

#no_primary_key ⇒ Object

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.

Artist.primary_key # => :id
Artist.no_primary_key
Artist.primary_key # => nil



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# File 'lib/sequel/model/base.rb', line 314

def no_primary_key
  clear_setter_methods_cache
  @simple_pk = @primary_key = nil
end

#plugin(plugin, *args, &blk) ⇒ Object

Loads a plugin for use with the model class, passing optional arguments to the plugin. If the plugin is a module, load it directly. Otherwise, require the plugin from either sequel/plugins/##plugin or sequel_##plugin, and then attempt to load the module using a the camelized plugin name under Sequel::Plugins.



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# File 'lib/sequel/model/base.rb', line 324

def plugin(plugin, *args, &blk)
  m = plugin.is_a?(Module) ? plugin : plugin_module(plugin)
  unless @plugins.include?(m)
    @plugins << m
    m.apply(self, *args, &blk) if m.respond_to?(:apply)
    include(m::InstanceMethods) if plugin_module_defined?(m, :InstanceMethods)
    extend(m::ClassMethods)if plugin_module_defined?(m, :ClassMethods)
    if plugin_module_defined?(m, :DatasetMethods)
      dataset.extend(m::DatasetMethods) if @dataset
      dataset_method_modules << m::DatasetMethods
      meths = m::DatasetMethods.public_instance_methods.reject{|x| NORMAL_METHOD_NAME_REGEXP !~ x.to_s}
      def_dataset_method(*meths) unless meths.empty?
    end
  end
  m.configure(self, *args, &blk) if m.respond_to?(:configure)
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.

Artist.primary_key_hash(1) # => {:id=>1}
Artist.primary_key_hash([1, 2]) # => {:id1=>1, :id2=>2}

Raises:



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# File 'lib/sequel/model/base.rb', line 349

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

#qualified_primary_key_hash(value, qualifier = table_name) ⇒ Object

Return a hash where the keys are qualified column references. Uses the given qualifier if provided, or the table_name otherwise. This is useful if you plan to join other tables to this table and you want the column references to be qualified.

Artist.filter(Artist.qualified_primary_key_hash(1))
# SELECT * FROM artists WHERE (artists.id = 1)



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# File 'lib/sequel/model/base.rb', line 368

def qualified_primary_key_hash(value, qualifier=table_name)
  h = primary_key_hash(value)
  h.to_a.each{|k,v| h[SQL::QualifiedIdentifier.new(qualifier, k)] = h.delete(k)}
  h
end

#restrict_primary_key ⇒ Object

Restrict the setting of the primary key(s) when using mass assignment (e.g. set). 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/model/base.rb', line 377

def restrict_primary_key
  clear_setter_methods_cache
  @restrict_primary_key = true
end

#restrict_primary_key? ⇒ Boolean

Whether or not setting the primary key(s) when using mass assignment (e.g. set) is restricted, true by default.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/base.rb', line 384

def restrict_primary_key?
  @restrict_primary_key
end

#set_allowed_columns(*cols) ⇒ Object

Set the columns to allow when using mass assignment (e.g. set). 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 during mass assignment, they need to be listed here as well (without the =).

It may be better to use a method such as set_only instead of this in places where only certain columns may be allowed.

Artist.set_allowed_columns(:name, :hometown)
Artist.set(:name=>'Bob', :hometown=>'Sactown') # No Error
Artist.set(:name=>'Bob', :records_sold=>30000) # Error



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# File 'lib/sequel/model/base.rb', line 399

def set_allowed_columns(*cols)
  clear_setter_methods_cache
  @allowed_columns = cols
end

#set_dataset(ds, opts = {}) ⇒ Object

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 database of 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 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.

Artist.set_dataset(:tbl_artists)
Artist.set_dataset(DB[:artists])



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# File 'lib/sequel/model/base.rb', line 419

def set_dataset(ds, opts={})
  inherited = opts[:inherited]
  @dataset = case ds
  when Symbol, SQL::Identifier, SQL::QualifiedIdentifier, SQL::AliasedExpression
    @simple_table = db.literal(ds)
    db[ds]
  when Dataset
    @simple_table = nil
    @db = ds.db
    ds
  else
    raise(Error, "Model.set_dataset takes one of the following classes as an argument: Symbol, SQL::Identifier, SQL::QualifiedIdentifier, SQL::AliasedExpression, Dataset")
  end
  @dataset.row_proc = Proc.new{|r| load(r)}
  @require_modification = Sequel::Model.require_modification.nil? ? @dataset.provides_accurate_rows_matched? : Sequel::Model.require_modification
  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=)
  check_non_connection_error{@db_schema = (inherited ? superclass.db_schema : get_db_schema)}
  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. To not use a primary key, set to nil or use no_primary_key.

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

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



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# File 'lib/sequel/model/base.rb', line 459

def set_primary_key(*key)
  clear_setter_methods_cache
  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 when using mass assignment (e.g. set). 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 during mass assignment, they need to be listed here as well (without the =).

It may be better to use a method such as set_except instead of this in places where certain columns are restricted. In general, it’s better to have a whitelist approach where you specify only what is allowed, as opposed to a blacklist approach that this method uses, where everything is allowed other than what you restrict.

Artist.set_restricted_column(:records_sold)
Artist.set(:name=>'Bob', :hometown=>'Sactown') # No Error
Artist.set(:name=>'Bob', :records_sold=>30000) # Error



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# File 'lib/sequel/model/base.rb', line 480

def set_restricted_columns(*cols)
  clear_setter_methods_cache
  @restricted_columns = cols
end

#setter_methods ⇒ Object

Cache of setter methods to allow by default, in order to speed up new/set/update instance methods.



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# File 'lib/sequel/model/base.rb', line 486

def setter_methods
  @setter_methods ||= if allowed_columns
    allowed_columns.map{|x| "#{x}="}
  else
    meths = instance_methods.collect{|x| x.to_s}.grep(SETTER_METHOD_REGEXP) - RESTRICTED_SETTER_METHODS
    meths -= Array(primary_key).map{|x| "#{x}="} if primary_key && restrict_primary_key?
    meths -= restricted_columns.map{|x| "#{x}="} if restricted_columns
    meths
  end
end

#subset(name, *args, &block) ⇒ Object

Shortcut for def_dataset_method that is restricted to modifying the dataset’s filter. Sometimes thought of as a scope, and like most dataset methods, they can be chained. For example:

Topic.subset(:joes, :username.like('%joe%'))
Topic.subset(:popular){num_posts > 100}
Topic.subset(:recent){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/model/base.rb', line 515

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

#table_name ⇒ Object

Returns name of primary table for the dataset. If the table for the dataset is aliased, returns the aliased name.

Artist.table_name # => :artists
Sequel::Model(:foo).table_name # => :foo
Sequel::Model(:foo___bar).table_name # => :bar



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# File 'lib/sequel/model/base.rb', line 525

def table_name
  dataset.first_source_alias
end

#unrestrict_primary_key ⇒ Object

Allow the setting of the primary key(s) when using the mass assignment methods.

Artist.set(:id=>1) # Error
Artist.unrestrict_primary_key
Artist.set(:id=>1) # No Error



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# File 'lib/sequel/model/base.rb', line 534

def unrestrict_primary_key
  clear_setter_methods_cache
  @restrict_primary_key = false
end