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tag: v3.1.9
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require 'active_support/core_ext/array/wrap'
require 'active_support/core_ext/object/inclusion'
require 'active_support/deprecation'
module ActiveRecord
module Associations
# = Active Record Associations
#
# This is the root class of all associations ('+ Foo' signifies an included module Foo):
#
# Association
# SingularAssociation
# HasOneAssociation
# HasOneThroughAssociation + ThroughAssociation
# BelongsToAssociation
# BelongsToPolymorphicAssociation
# CollectionAssociation
# HasAndBelongsToManyAssociation
# HasManyAssociation
# HasManyThroughAssociation + ThroughAssociation
class Association #:nodoc:
attr_reader :owner, :target, :reflection
delegate :options, :to => :reflection
def initialize(owner, reflection)
reflection.check_validity!
@target = nil
@owner, @reflection = owner, reflection
@updated = false
reset
reset_scope
end
# Returns the name of the table of the related class:
#
# post.comments.aliased_table_name # => "comments"
#
def aliased_table_name
reflection.klass.table_name
end
# Resets the \loaded flag to +false+ and sets the \target to +nil+.
def reset
@loaded = false
IdentityMap.remove(target) if IdentityMap.enabled? && target
@target = nil
end
# Reloads the \target and returns +self+ on success.
def reload
reset
reset_scope
load_target
self unless target.nil?
end
# Has the \target been already \loaded?
def loaded?
@loaded
end
# Asserts the \target has been loaded setting the \loaded flag to +true+.
def loaded!
@loaded = true
@stale_state = stale_state
end
# The target is stale if the target no longer points to the record(s) that the
# relevant foreign_key(s) refers to. If stale, the association accessor method
# on the owner will reload the target. It's up to subclasses to implement the
# state_state method if relevant.
#
# Note that if the target has not been loaded, it is not considered stale.
def stale_target?
loaded? && @stale_state != stale_state
end
# Sets the target of this association to <tt>\target</tt>, and the \loaded flag to +true+.
def target=(target)
@target = target
loaded!
end
def scoped
target_scope.merge(association_scope)
end
# The scope for this association.
#
# Note that the association_scope is merged into the target_scope only when the
# scoped method is called. This is because at that point the call may be surrounded
# by scope.scoping { ... } or with_scope { ... } etc, which affects the scope which
# actually gets built.
def association_scope
if klass
@association_scope ||= AssociationScope.new(self).scope
end
end
def reset_scope
@association_scope = nil
end
# Set the inverse association, if possible
def set_inverse_instance(record)
if record && invertible_for?(record)
inverse = record.association(inverse_reflection_for(record).name)
inverse.target = owner
end
end
# This class of the target. belongs_to polymorphic overrides this to look at the
# polymorphic_type field on the owner.
def klass
reflection.klass
end
# Can be overridden (i.e. in ThroughAssociation) to merge in other scopes (i.e. the
# through association's scope)
def target_scope
klass.scoped
end
# Loads the \target if needed and returns it.
#
# This method is abstract in the sense that it relies on +find_target+,
# which is expected to be provided by descendants.
#
# If the \target is already \loaded it is just returned. Thus, you can call
# +load_target+ unconditionally to get the \target.
#
# ActiveRecord::RecordNotFound is rescued within the method, and it is
# not reraised. The proxy is \reset and +nil+ is the return value.
def load_target
if find_target?
begin
if IdentityMap.enabled? && association_class && association_class.respond_to?(:base_class)
@target = IdentityMap.get(association_class, owner[reflection.foreign_key])
end
rescue NameError
nil
ensure
@target ||= find_target
end
end
loaded! unless loaded?
target
rescue ActiveRecord::RecordNotFound
reset
end
def interpolate(sql, record = nil)
if sql.respond_to?(:to_proc)
owner.send(:instance_exec, record, &sql)
else
sql
end
end
private
def find_target?
!loaded? && (!owner.new_record? || foreign_key_present?) && klass
end
def creation_attributes
attributes = {}
if reflection.macro.in?([:has_one, :has_many]) && !options[:through]
attributes[reflection.foreign_key] = owner[reflection.active_record_primary_key]
if reflection.options[:as]
attributes[reflection.type] = owner.class.base_class.name
end
end
attributes
end
# Sets the owner attributes on the given record
def set_owner_attributes(record)
creation_attributes.each { |key, value| record[key] = value }
end
# Should be true if there is a foreign key present on the owner which
# references the target. This is used to determine whether we can load
# the target if the owner is currently a new record (and therefore
# without a key).
#
# Currently implemented by belongs_to (vanilla and polymorphic) and
# has_one/has_many :through associations which go through a belongs_to
def foreign_key_present?
false
end
# Raises ActiveRecord::AssociationTypeMismatch unless +record+ is of
# the kind of the class of the associated objects. Meant to be used as
# a sanity check when you are about to assign an associated record.
def raise_on_type_mismatch(record)
unless record.is_a?(reflection.klass) || record.is_a?(reflection.class_name.constantize)
message = "#{reflection.class_name}(##{reflection.klass.object_id}) expected, got #{record.class}(##{record.class.object_id})"
raise ActiveRecord::AssociationTypeMismatch, message
end
end
# Can be redefined by subclasses, notably polymorphic belongs_to
# The record parameter is necessary to support polymorphic inverses as we must check for
# the association in the specific class of the record.
def inverse_reflection_for(record)
reflection.inverse_of
end
# Is this association invertible? Can be redefined by subclasses.
def invertible_for?(record)
inverse_reflection_for(record)
end
# This should be implemented to return the values of the relevant key(s) on the owner,
# so that when state_state is different from the value stored on the last find_target,
# the target is stale.
#
# This is only relevant to certain associations, which is why it returns nil by default.
def stale_state
end
def association_class
@reflection.klass
end
def build_record(attributes, options)
reflection.original_build_association_called = false
record = reflection.build_association(attributes, options) do |r|
r.assign_attributes(
create_scope.except(*r.changed),
:without_protection => true
)
end
if !reflection.original_build_association_called &&
(record.changed & create_scope.keys) != create_scope.keys
# We have detected that there is an overridden AssociationReflection#build_association
# method, but it looks like it has not passed through the block above. So try again and
# show a noisy deprecation warning.
record.assign_attributes(
create_scope.except(*record.changed),
:without_protection => true
)
method = reflection.method(:build_association)
if RUBY_VERSION >= '1.9.2'
source = method.source_location
debug_info = "It looks like the method is defined in #{source[0]} at line #{source[1]}."
else
debug_info = "This might help you find the method: #{method}. If you run this on Ruby 1.9.2 we can tell you exactly where the method is."
end
ActiveSupport::Deprecation.warn <<-WARN
It looks like ActiveRecord::Reflection::AssociationReflection#build_association has been redefined, either by you or by a plugin or library that you are using. The signature of this method has changed.
Before: def build_association(*options)
After: def build_association(*options, &block)
The block argument now needs to be passed through to ActiveRecord::Base#new when this method is overridden, or else your associations will not function correctly in Rails 3.2.
#{debug_info}
WARN
end
record
end
end
end
end
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