--- /dev/null
+module ActiveRecord
+ module Associations
+ # This is the root class of all association proxies:
+ #
+ # AssociationProxy
+ # BelongsToAssociation
+ # HasOneAssociation
+ # BelongsToPolymorphicAssociation
+ # AssociationCollection
+ # HasAndBelongsToManyAssociation
+ # HasManyAssociation
+ # HasManyThroughAssociation
+ # HasOneThroughAssociation
+ #
+ # 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_respond_to?, :respond_to?
+ alias_method :proxy_extend, :extend
+ delegate :to_param, :to => :proxy_target
+ instance_methods.each { |m| undef_method m unless m =~ /(^__|^nil\?$|^send$|proxy_|^object_id$)/ }
+
+ def initialize(owner, reflection)
+ @owner, @reflection = owner, reflection
+ Array(reflection.options[:extend]).each { |ext| proxy_extend(ext) }
+ reset
+ 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
+
+ # Returns the \target of the proxy, same as +target+.
+ def proxy_target
+ @target
+ end
+
+ # Does the proxy or its \target respond to +symbol+?
+ def respond_to?(*args)
+ proxy_respond_to?(*args) || (load_target && @target.respond_to?(*args))
+ 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)
+ load_target
+ other === @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
+
+ # Returns the SQL string that corresponds to the <tt>:conditions</tt>
+ # option of the macro, if given, or +nil+ otherwise.
+ def conditions
+ @conditions ||= interpolate_sql(@reflection.sanitized_conditions) if @reflection.sanitized_conditions
+ end
+ alias :sql_conditions :conditions
+
+ # Resets the \loaded flag to +false+ and sets the \target to +nil+.
+ def reset
+ @loaded = false
+ @target = nil
+ end
+
+ # Reloads the \target and returns +self+ on success.
+ def reload
+ reset
+ 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
+ end
+
+ # Returns the target of this proxy, same as +proxy_target+.
+ def target
+ @target
+ end
+
+ # 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
+ @target.inspect
+ end
+
+ def send(method, *args)
+ if proxy_respond_to?(method)
+ super
+ else
+ load_target
+ @target.send(method, *args)
+ end
+ end
+
+ protected
+ # Does the association have a <tt>:dependent</tt> option?
+ def dependent?
+ @reflection.options[:dependent]
+ end
+
+ # Returns a string with the IDs of +records+ joined with a comma, quoted
+ # if needed. The result is ready to be inserted into a SQL IN clause.
+ #
+ # quoted_record_ids(records) # => "23,56,58,67"
+ #
+ def quoted_record_ids(records)
+ records.map { |record| record.quoted_id }.join(',')
+ end
+
+ def interpolate_sql(sql, record = nil)
+ @owner.send(:interpolate_sql, sql, record)
+ end
+
+ # Forwards the call to the reflection class.
+ def sanitize_sql(sql)
+ @reflection.klass.send(:sanitize_sql, sql)
+ end
+
+ # Assigns the ID of the owner to the corresponding foreign key in +record+.
+ # If the association is polymorphic the type of the owner is also set.
+ def set_belongs_to_association_for(record)
+ if @reflection.options[:as]
+ record["#{@reflection.options[:as]}_id"] = @owner.id unless @owner.new_record?
+ record["#{@reflection.options[:as]}_type"] = @owner.class.base_class.name.to_s
+ else
+ record[@reflection.primary_key_name] = @owner.id unless @owner.new_record?
+ end
+ end
+
+ # Merges into +options+ the ones coming from the reflection.
+ def merge_options_from_reflection!(options)
+ options.reverse_merge!(
+ :group => @reflection.options[:group],
+ :limit => @reflection.options[:limit],
+ :offset => @reflection.options[:offset],
+ :joins => @reflection.options[:joins],
+ :include => @reflection.options[:include],
+ :select => @reflection.options[:select],
+ :readonly => @reflection.options[:readonly]
+ )
+ end
+
+ # Forwards +with_scope+ to the reflection.
+ def with_scope(*args, &block)
+ @reflection.klass.send :with_scope, *args, &block
+ end
+
+ private
+ # Forwards any missing method call to the \target.
+ def method_missing(method, *args)
+ if load_target
+ raise NoMethodError unless @target.respond_to?(method)
+
+ if block_given?
+ @target.send(method, *args) { |*block_args| yield(*block_args) }
+ else
+ @target.send(method, *args)
+ end
+ end
+ 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
+ return nil unless defined?(@loaded)
+
+ if !loaded? and (!@owner.new_record? || foreign_key_present)
+ @target = find_target
+ end
+
+ @loaded = true
+ @target
+ rescue ActiveRecord::RecordNotFound
+ reset
+ end
+
+ # Can be overwritten by associations that might have the foreign key
+ # available for an association without having the object itself (and
+ # still being a new record). Currently, only +belongs_to+ presents
+ # this scenario (both vanilla and polymorphic).
+ 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
+
+ # Array#flatten has problems with recursive arrays. Going one level
+ # deeper solves the majority of the problems.
+ def flatten_deeper(array)
+ array.collect { |element| (element.respond_to?(:flatten) && !element.is_a?(Hash)) ? element.flatten : element }.flatten
+ end
+
+ # Returns the ID of the owner, quoted if needed.
+ def owner_quoted_id
+ @owner.quoted_id
+ end
+ end
+ end
+end
projects / depot.git / blobdiff