diff options
Diffstat (limited to 'activerecord/lib/active_record/associations/association_proxy.rb')
| -rw-r--r-- | activerecord/lib/active_record/associations/association_proxy.rb | 348 |
1 files changed, 0 insertions, 348 deletions
diff --git a/activerecord/lib/active_record/associations/association_proxy.rb b/activerecord/lib/active_record/associations/association_proxy.rb deleted file mode 100644 index d16cda5585..0000000000 --- a/activerecord/lib/active_record/associations/association_proxy.rb +++ /dev/null @@ -1,348 +0,0 @@ -require 'active_support/core_ext/array/wrap' - -module ActiveRecord - module Associations - # = Active Record Associations - # - # This is the root class of all association proxies ('+ Foo' signifies an included module Foo): - # - # AssociationProxy - # SingularAssociaton - # HasOneAssociation - # HasOneThroughAssociation + ThroughAssociation - # BelongsToAssociation - # BelongsToPolymorphicAssociation - # AssociationCollection - # HasAndBelongsToManyAssociation - # HasManyAssociation - # HasManyThroughAssociation + ThroughAssociation - # - # Association proxies in Active Record are middlemen between the object that - # holds the association, known as the <tt>@owner</tt>, and the actual associated - # object, known as the <tt>@target</tt>. The kind of association any proxy is - # about is available in <tt>@reflection</tt>. That's an instance of the class - # ActiveRecord::Reflection::AssociationReflection. - # - # For example, given - # - # class Blog < ActiveRecord::Base - # has_many :posts - # end - # - # blog = Blog.find(:first) - # - # the association proxy in <tt>blog.posts</tt> has the object in +blog+ as - # <tt>@owner</tt>, the collection of its posts as <tt>@target</tt>, and - # the <tt>@reflection</tt> object represents a <tt>:has_many</tt> macro. - # - # This class has most of the basic instance methods removed, and delegates - # unknown methods to <tt>@target</tt> via <tt>method_missing</tt>. As a - # corner case, it even removes the +class+ method and that's why you get - # - # blog.posts.class # => Array - # - # though the object behind <tt>blog.posts</tt> is not an Array, but an - # ActiveRecord::Associations::HasManyAssociation. - # - # The <tt>@target</tt> object is not \loaded until needed. For example, - # - # blog.posts.count - # - # is computed directly through SQL and does not trigger by itself the - # instantiation of the actual post records. - class AssociationProxy #:nodoc: - alias_method :proxy_extend, :extend - - instance_methods.each { |m| undef_method m unless m.to_s =~ /^(?:nil\?|send|object_id|to_a)$|^__|^respond_to|proxy_/ } - - def initialize(owner, reflection) - @owner, @reflection = owner, reflection - @updated = false - reflection.check_validity! - Array.wrap(reflection.options[:extend]).each { |ext| proxy_extend(ext) } - reset - construct_scope - end - - def to_param - proxy_target.to_param - end - - # Returns the owner of the proxy. - def proxy_owner - @owner - end - - # Returns the reflection object that represents the association handled - # by the proxy. - def proxy_reflection - @reflection - end - - # Does the proxy or its \target respond to +symbol+? - def respond_to?(*args) - super || (load_target && @target.respond_to?(*args)) - end - - # Forwards any missing method call to the \target. - def method_missing(method, *args, &block) - if load_target - return super unless @target.respond_to?(method) - @target.send(method, *args, &block) - end - rescue NoMethodError => e - raise e, e.message.sub(/ for #<.*$/, " via proxy for #{@target}") - end - - # Forwards <tt>===</tt> explicitly to the \target because the instance method - # removal above doesn't catch it. Loads the \target if needed. - def ===(other) - other === load_target - 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 defined?(@target) && @target && IdentityMap.enabled? - @target = nil - end - - # Reloads the \target and returns +self+ on success. - def reload - reset - construct_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 - - # Returns the target of this proxy, same as +proxy_target+. - attr_reader :target - - # Returns the \target of the proxy, same as +target+. - alias :proxy_target :target - - # Sets the target of this proxy to <tt>\target</tt>, and the \loaded flag to +true+. - def target=(target) - @target = target - loaded! - end - - # Forwards the call to the target. Loads the \target if needed. - def inspect - load_target.inspect - end - - def send(method, *args) - return super if respond_to?(method) - load_target.send(method, *args) - end - - def scoped - target_scope.merge(@association_scope) - end - - protected - - # Construct the scope for this association. - # - # Note that the association_scope is merged into the targed_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 construct_scope - @association_scope = association_scope if target_klass - end - - def association_scope - scope = target_klass.unscoped - scope = scope.create_with(creation_attributes) - scope = scope.apply_finder_options(@reflection.options.slice(:readonly, :include)) - scope = scope.where(interpolate(@reflection.options[:conditions])) - if select = select_value - scope = scope.select(select) - end - scope = scope.extending(*Array.wrap(@reflection.options[:extend])) - scope.where(construct_owner_conditions) - end - - def aliased_table - target_klass.arel_table - end - - # Set the inverse association, if possible - def set_inverse_instance(record) - if record && invertible_for?(record) - inverse = record.send(:association_proxy, 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 target_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 - target_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! - target - rescue ActiveRecord::RecordNotFound - reset - end - - private - - def find_target? - !loaded? && (!@owner.new_record? || foreign_key_present?) && target_klass - end - - def interpolate(sql, record = nil) - if sql.respond_to?(:to_proc) - @owner.send(:instance_exec, record, &sql) - else - sql - end - end - - def select_value - @reflection.options[:select] - end - - # Implemented by (some) subclasses - def creation_attributes - { } - end - - # Returns a hash linking the owner to the association represented by the reflection - def construct_owner_attributes(reflection = @reflection) - attributes = {} - if reflection.macro == :belongs_to - attributes[reflection.association_primary_key] = @owner[reflection.foreign_key] - else - attributes[reflection.foreign_key] = @owner[reflection.active_record_primary_key] - - if reflection.options[:as] - attributes["#{reflection.options[:as]}_type"] = @owner.class.base_class.name - end - end - attributes - end - - # Builds an array of arel nodes from the owner attributes hash - def construct_owner_conditions(table = aliased_table, reflection = @reflection) - conditions = construct_owner_attributes(reflection).map do |attr, value| - table[attr].eq(value) - end - table.create_and(conditions) - end - - # Sets the owner attributes on the given record - def set_owner_attributes(record) - if @owner.persisted? - construct_owner_attributes.each { |key, value| record[key] = value } - end - 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 - end - end -end |