diff options
Diffstat (limited to 'activerecord/lib/active_record/reflection.rb')
| -rw-r--r-- | activerecord/lib/active_record/reflection.rb | 118 |
1 files changed, 101 insertions, 17 deletions
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb index 5de08953f9..e801bc4afa 100644 --- a/activerecord/lib/active_record/reflection.rb +++ b/activerecord/lib/active_record/reflection.rb @@ -262,16 +262,30 @@ module ActiveRecord end def through_reflection - false - end - - def through_reflection_foreign_key + nil end def source_reflection nil end + # A chain of reflections from this one back to the owner. For more see the explanation in + # ThroughReflection. + def chain + [self] + end + + # An array of arrays of conditions. Each item in the outside array corresponds to a reflection + # in the #chain. The inside arrays are simply conditions (and each condition may itself be + # a hash, array, arel predicate, etc...) + def conditions + conditions = [options[:conditions]].compact + conditions << { type => active_record.base_class.name } if options[:as] + [conditions] + end + + alias :source_macro :macro + def has_inverse? @options[:inverse_of] end @@ -363,7 +377,7 @@ module ActiveRecord # Holds all the meta-data about a :through association as it was specified # in the Active Record class. class ThroughReflection < AssociationReflection #:nodoc: - delegate :association_primary_key, :foreign_type, :to => :source_reflection + delegate :foreign_key, :foreign_type, :association_foreign_key, :active_record_primary_key, :to => :source_reflection # Gets the source of the through reflection. It checks both a singularized # and pluralized form for <tt>:belongs_to</tt> or <tt>:has_many</tt>. @@ -392,6 +406,88 @@ module ActiveRecord @through_reflection ||= active_record.reflect_on_association(options[:through]) end + # Returns an array of reflections which are involved in this association. Each item in the + # array corresponds to a table which will be part of the query for this association. + # + # The chain is built by recursively calling #chain on the source reflection and the through + # reflection. The base case for the recursion is a normal association, which just returns + # [self] as its #chain. + def chain + @chain ||= begin + chain = source_reflection.chain + through_reflection.chain + chain[0] = self # Use self so we don't lose the information from :source_type + chain + end + end + + # Consider the following example: + # + # class Person + # has_many :articles + # has_many :comment_tags, :through => :articles + # end + # + # class Article + # has_many :comments + # has_many :comment_tags, :through => :comments, :source => :tags + # end + # + # class Comment + # has_many :tags + # end + # + # There may be conditions on Person.comment_tags, Article.comment_tags and/or Comment.tags, + # but only Comment.tags will be represented in the #chain. So this method creates an array + # of conditions corresponding to the chain. Each item in the #conditions array corresponds + # to an item in the #chain, and is itself an array of conditions from an arbitrary number + # of relevant reflections, plus any :source_type or polymorphic :as constraints. + def conditions + @conditions ||= begin + conditions = source_reflection.conditions + + # Add to it the conditions from this reflection if necessary. + conditions.first << options[:conditions] if options[:conditions] + + through_conditions = through_reflection.conditions + + if options[:source_type] + through_conditions.first << { foreign_type => options[:source_type] } + end + + # Recursively fill out the rest of the array from the through reflection + conditions += through_conditions + + # And return + conditions + end + end + + # The macro used by the source association + def source_macro + source_reflection.source_macro + end + + # A through association is nested iff there would be more than one join table + def nested? + chain.length > 2 || through_reflection.macro == :has_and_belongs_to_many + end + + # We want to use the klass from this reflection, rather than just delegate straight to + # the source_reflection, because the source_reflection may be polymorphic. We still + # need to respect the source_reflection's :primary_key option, though. + def association_primary_key + @association_primary_key ||= begin + # Get the "actual" source reflection if the immediate source reflection has a + # source reflection itself + source_reflection = self.source_reflection + while source_reflection.source_reflection + source_reflection = source_reflection.source_reflection + end + + source_reflection.options[:primary_key] || klass.primary_key + end + end + # Gets an array of possible <tt>:through</tt> source reflection names: # # [:singularized, :pluralized] @@ -429,10 +525,6 @@ module ActiveRecord raise HasManyThroughAssociationPolymorphicSourceError.new(active_record.name, self, source_reflection) end - unless [:belongs_to, :has_many, :has_one].include?(source_reflection.macro) && source_reflection.options[:through].nil? - raise HasManyThroughSourceAssociationMacroError.new(self) - end - if macro == :has_one && through_reflection.collection? raise HasOneThroughCantAssociateThroughCollection.new(active_record.name, self, through_reflection) end @@ -440,14 +532,6 @@ module ActiveRecord check_validity_of_inverse! end - def through_reflection_primary_key - through_reflection.belongs_to? ? through_reflection.klass.primary_key : through_reflection.foreign_key - end - - def through_reflection_foreign_key - through_reflection.foreign_key if through_reflection.belongs_to? - end - private def derive_class_name # get the class_name of the belongs_to association of the through reflection |