Class: ActiveRecord::Reflection::AssociationReflection

Inherits:
MacroReflection show all
Defined in:
activerecord/lib/active_record/reflection.rb

Overview

Holds all the meta-data about an association as it was specified in the Active Record class.

Direct Known Subclasses

ThroughReflection

Constant Summary collapse

VALID_AUTOMATIC_INVERSE_MACROS =
[:has_many, :has_one, :belongs_to]
INVALID_AUTOMATIC_INVERSE_OPTIONS =
[:conditions, :through, :polymorphic, :foreign_key]

Instance Attribute Summary collapse

Attributes inherited from MacroReflection

#active_record, #macro, #name, #options, #plural_name, #scope

Instance Method Summary collapse

Methods inherited from MacroReflection

#==, #autosave=, #class_name

Constructor Details

#initialize(macro, name, scope, options, active_record) ⇒ AssociationReflection

Returns a new instance of AssociationReflection


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# File 'activerecord/lib/active_record/reflection.rb', line 196

def initialize(macro, name, scope, options, active_record)
  super
  @collection = [:has_many, :has_and_belongs_to_many].include?(macro)
  @automatic_inverse_of = nil
  @type         = options[:as] && "#{options[:as]}_type"
  @foreign_type = options[:foreign_type] || "#{name}_type"
end

Instance Attribute Details

#foreign_typeObject (readonly)

Returns the value of attribute foreign_type


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# File 'activerecord/lib/active_record/reflection.rb', line 194

def foreign_type
  @foreign_type
end

#typeObject (readonly)

Returns the value of attribute type


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# File 'activerecord/lib/active_record/reflection.rb', line 194

def type
  @type
end

Instance Method Details

#active_record_primary_keyObject


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# File 'activerecord/lib/active_record/reflection.rb', line 239

def active_record_primary_key
  @active_record_primary_key ||= options[:primary_key] || primary_key(active_record)
end

#association_classObject


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# File 'activerecord/lib/active_record/reflection.rb', line 342

def association_class
  case macro
  when :belongs_to
    if options[:polymorphic]
      Associations::BelongsToPolymorphicAssociation
    else
      Associations::BelongsToAssociation
    end
  when :has_and_belongs_to_many
    Associations::HasAndBelongsToManyAssociation
  when :has_many
    if options[:through]
      Associations::HasManyThroughAssociation
    else
      Associations::HasManyAssociation
    end
  when :has_one
    if options[:through]
      Associations::HasOneThroughAssociation
    else
      Associations::HasOneAssociation
    end
  end
end

#association_foreign_keyObject


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# File 'activerecord/lib/active_record/reflection.rb', line 230

def association_foreign_key
  @association_foreign_key ||= options[:association_foreign_key] || class_name.foreign_key
end

#association_primary_key(klass = nil) ⇒ Object

klass option is necessary to support loading polymorphic associations


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# File 'activerecord/lib/active_record/reflection.rb', line 235

def association_primary_key(klass = nil)
  options[:primary_key] || primary_key(klass || self.klass)
end

#belongs_to?Boolean

Returns true if self is a belongs_to reflection.

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/reflection.rb', line 334

def belongs_to?
  macro == :belongs_to
end

#build_association(attributes, &block) ⇒ Object

Returns a new, unsaved instance of the associated class. attributes will be passed to the class's constructor.


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# File 'activerecord/lib/active_record/reflection.rb', line 206

def build_association(attributes, &block)
  klass.new(attributes, &block)
end

#chainObject

A chain of reflections from this one back to the owner. For more see the explanation in ThroughReflection.


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# File 'activerecord/lib/active_record/reflection.rb', line 277

def chain
  [self]
end

#check_validity!Object


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# File 'activerecord/lib/active_record/reflection.rb', line 251

def check_validity!
  check_validity_of_inverse!

  if has_and_belongs_to_many? && association_foreign_key == foreign_key
    raise HasAndBelongsToManyAssociationForeignKeyNeeded.new(self)
  end
end

#check_validity_of_inverse!Object


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# File 'activerecord/lib/active_record/reflection.rb', line 259

def check_validity_of_inverse!
  unless options[:polymorphic]
    if has_inverse? && inverse_of.nil?
      raise InverseOfAssociationNotFoundError.new(self)
    end
  end
end

#collection?Boolean

Returns whether or not this association reflection is for a collection association. Returns true if the macro is either has_many or has_and_belongs_to_many, false otherwise.

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/reflection.rb', line 316

def collection?
  @collection
end

#counter_cache_columnObject


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# File 'activerecord/lib/active_record/reflection.rb', line 243

def counter_cache_column
  if options[:counter_cache] == true
    "#{active_record.name.demodulize.underscore.pluralize}_count"
  elsif options[:counter_cache]
    options[:counter_cache].to_s
  end
end

#foreign_keyObject


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# File 'activerecord/lib/active_record/reflection.rb', line 222

def foreign_key
  @foreign_key ||= options[:foreign_key] || derive_foreign_key
end

#has_and_belongs_to_many?Boolean

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/reflection.rb', line 338

def has_and_belongs_to_many?
  macro == :has_and_belongs_to_many
end

#has_inverse?Boolean

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/reflection.rb', line 293

def has_inverse?
  inverse_name
end

#inverse_ofObject


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# File 'activerecord/lib/active_record/reflection.rb', line 297

def inverse_of
  return unless inverse_name

  @inverse_of ||= klass.reflect_on_association inverse_name
end

#join_tableObject


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# File 'activerecord/lib/active_record/reflection.rb', line 218

def join_table
  @join_table ||= options[:join_table] || derive_join_table
end

#klassObject

Returns the target association's class.

class Author < ActiveRecord::Base
  has_many :books
end

Author.reflect_on_association(:books).klass
# => Book

Note: Do not call klass.new or klass.create to instantiate a new association object. Use build_association or create_association instead. This allows plugins to hook into association object creation.


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# File 'activerecord/lib/active_record/reflection.rb', line 190

def klass
  @klass ||= active_record.send(:compute_type, class_name)
end

#nested?Boolean

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/reflection.rb', line 281

def nested?
  false
end

#polymorphic?Boolean

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/reflection.rb', line 367

def polymorphic?
  options.key? :polymorphic
end

#polymorphic_inverse_of(associated_class) ⇒ Object


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# File 'activerecord/lib/active_record/reflection.rb', line 303

def polymorphic_inverse_of(associated_class)
  if has_inverse?
    if inverse_relationship = associated_class.reflect_on_association(options[:inverse_of])
      inverse_relationship
    else
      raise InverseOfAssociationNotFoundError.new(self, associated_class)
    end
  end
end

#primary_key_columnObject


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# File 'activerecord/lib/active_record/reflection.rb', line 226

def primary_key_column
  klass.columns_hash[klass.primary_key]
end

#quoted_table_nameObject


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# File 'activerecord/lib/active_record/reflection.rb', line 214

def quoted_table_name
  klass.quoted_table_name
end

#scope_chainObject

An array of arrays of scopes. Each item in the outside array corresponds to a reflection in the #chain.


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# File 'activerecord/lib/active_record/reflection.rb', line 287

def scope_chain
  scope ? [[scope]] : [[]]
end

#source_reflectionObject


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# File 'activerecord/lib/active_record/reflection.rb', line 271

def source_reflection
  self
end

#table_nameObject


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# File 'activerecord/lib/active_record/reflection.rb', line 210

def table_name
  klass.table_name
end

#through_reflectionObject


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# File 'activerecord/lib/active_record/reflection.rb', line 267

def through_reflection
  nil
end

#validate?Boolean

Returns whether or not the association should be validated as part of the parent's validation.

Unless you explicitly disable validation with validate: false, validation will take place when:

  • you explicitly enable validation; validate: true

  • you use autosave; autosave: true

  • the association is a has_many association

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/reflection.rb', line 329

def validate?
  !options[:validate].nil? ? options[:validate] : (options[:autosave] == true || macro == :has_many)
end