module ActiveRecord module AssociationPreload #:nodoc: def self.included(base) base.extend(ClassMethods) end module ClassMethods # Loads the named associations for the activerecord record (or records) given # preload_options is passed only one level deep: don't pass to the child associations when associations is a Hash protected def preload_associations(records, associations, preload_options={}) records = [records].flatten.compact.uniq return if records.empty? case associations when Array then associations.each {|association| preload_associations(records, association, preload_options)} when Symbol, String then preload_one_association(records, associations.to_sym, preload_options) when Hash then associations.each do |parent, child| raise "parent must be an association name" unless parent.is_a?(String) || parent.is_a?(Symbol) preload_associations(records, parent, preload_options) reflection = reflections[parent] parents = records.map {|record| record.send(reflection.name)}.flatten unless parents.empty? || parents.first.nil? parents.first.class.preload_associations(parents, child) end end end end private def preload_one_association(records, association, preload_options={}) class_to_reflection = {} # Not all records have the same class, so group then preload # group on the reflection itself so that if various subclass share the same association then we do not split them # unnecessarily records.group_by {|record| class_to_reflection[record.class] ||= record.class.reflections[association]}.each do |reflection, records| raise ConfigurationError, "Association named '#{ association }' was not found; perhaps you misspelled it?" unless reflection send("preload_#{reflection.macro}_association", records, reflection, preload_options) end end def add_preloaded_records_to_collection(parent_records, reflection_name, associated_record) parent_records.each do |parent_record| association_proxy = parent_record.send(reflection_name) association_proxy.loaded association_proxy.target.push(*[associated_record].flatten) end end def add_preloaded_record_to_collection(parent_records, reflection_name, associated_record) parent_records.each do |parent_record| parent_record.send("set_#{reflection_name}_target", associated_record) end end def set_association_collection_records(id_to_record_map, reflection_name, associated_records, key) associated_records.each do |associated_record| mapped_records = id_to_record_map[associated_record[key].to_s] add_preloaded_records_to_collection(mapped_records, reflection_name, associated_record) end end def set_association_single_records(id_to_record_map, reflection_name, associated_records, key) seen_keys = {} associated_records.each do |associated_record| #this is a has_one or belongs_to: there should only be one record. #Unfortunately we can't (in portable way) ask the database for 'all records where foo_id in (x,y,z), but please # only one row per distinct foo_id' so this where we enforce that next if seen_keys[associated_record[key].to_s] seen_keys[associated_record[key].to_s] = true mapped_records = id_to_record_map[associated_record[key].to_s] mapped_records.each do |mapped_record| mapped_record.send("set_#{reflection_name}_target", associated_record) end end end def construct_id_map(records) id_to_record_map = {} ids = [] records.each do |record| ids << record.id mapped_records = (id_to_record_map[record.id.to_s] ||= []) mapped_records << record end ids.uniq! return id_to_record_map, ids end def preload_has_and_belongs_to_many_association(records, reflection, preload_options={}) table_name = reflection.klass.quoted_table_name id_to_record_map, ids = construct_id_map(records) records.each {|record| record.send(reflection.name).loaded} options = reflection.options conditions = "t0.#{reflection.primary_key_name} #{in_or_equals_for_ids(ids)}" conditions << append_conditions(options, preload_options) associated_records = reflection.klass.find(:all, :conditions => [conditions, ids], :include => options[:include], :joins => "INNER JOIN #{connection.quote_table_name options[:join_table]} as t0 ON #{reflection.klass.quoted_table_name}.#{reflection.klass.primary_key} = t0.#{reflection.association_foreign_key}", :select => "#{options[:select] || table_name+'.*'}, t0.#{reflection.primary_key_name} as the_parent_record_id", :order => options[:order]) set_association_collection_records(id_to_record_map, reflection.name, associated_records, 'the_parent_record_id') end def preload_has_one_association(records, reflection, preload_options={}) id_to_record_map, ids = construct_id_map(records) options = reflection.options records.each {|record| record.send("set_#{reflection.name}_target", nil)} if options[:through] through_records = preload_through_records(records, reflection, options[:through]) through_reflection = reflections[options[:through]] through_primary_key = through_reflection.primary_key_name unless through_records.empty? source = reflection.source_reflection.name through_records.first.class.preload_associations(through_records, source) through_records.each do |through_record| add_preloaded_record_to_collection(id_to_record_map[through_record[through_primary_key].to_s], reflection.name, through_record.send(source)) end end else set_association_single_records(id_to_record_map, reflection.name, find_associated_records(ids, reflection, preload_options), reflection.primary_key_name) end end def preload_has_many_association(records, reflection, preload_options={}) id_to_record_map, ids = construct_id_map(records) records.each {|record| record.send(reflection.name).loaded} options = reflection.options if options[:through] through_records = preload_through_records(records, reflection, options[:through]) through_reflection = reflections[options[:through]] through_primary_key = through_reflection.primary_key_name unless through_records.empty? source = reflection.source_reflection.name #add conditions from reflection! through_records.first.class.preload_associations(through_records, source, reflection.options) through_records.each do |through_record| add_preloaded_records_to_collection(id_to_record_map[through_record[through_primary_key].to_s], reflection.name, through_record.send(source)) end end else set_association_collection_records(id_to_record_map, reflection.name, find_associated_records(ids, reflection, preload_options), reflection.primary_key_name) end end def preload_through_records(records, reflection, through_association) through_reflection = reflections[through_association] through_primary_key = through_reflection.primary_key_name if reflection.options[:source_type] interface = reflection.source_reflection.options[:foreign_type] preload_options = {:conditions => ["#{connection.quote_column_name interface} = ?", reflection.options[:source_type]]} records.compact! records.first.class.preload_associations(records, through_association, preload_options) # Dont cache the association - we would only be caching a subset through_records = [] records.each do |record| proxy = record.send(through_association) if proxy.respond_to?(:target) through_records << proxy.target proxy.reset else # this is a has_one :through reflection through_records << proxy if proxy end end through_records.flatten! else records.first.class.preload_associations(records, through_association) through_records = records.map {|record| record.send(through_association)}.flatten end through_records.compact! through_records end def preload_belongs_to_association(records, reflection, preload_options={}) options = reflection.options primary_key_name = reflection.primary_key_name if options[:polymorphic] polymorph_type = options[:foreign_type] klasses_and_ids = {} # Construct a mapping from klass to a list of ids to load and a mapping of those ids back to their parent_records records.each do |record| if klass = record.send(polymorph_type) klass_id = record.send(primary_key_name) if klass_id id_map = klasses_and_ids[klass] ||= {} id_list_for_klass_id = (id_map[klass_id.to_s] ||= []) id_list_for_klass_id << record end end end klasses_and_ids = klasses_and_ids.to_a else id_map = {} records.each do |record| key = record.send(primary_key_name) if key mapped_records = (id_map[key.to_s] ||= []) mapped_records << record end end klasses_and_ids = [[reflection.klass.name, id_map]] end klasses_and_ids.each do |klass_and_id| klass_name, id_map = *klass_and_id klass = klass_name.constantize table_name = klass.quoted_table_name primary_key = klass.primary_key column_type = klass.columns.detect{|c| c.name == primary_key}.type ids = id_map.keys.uniq.map do |id| if column_type == :integer id.to_i elsif column_type == :float id.to_f else id end end conditions = "#{table_name}.#{connection.quote_column_name(primary_key)} #{in_or_equals_for_ids(ids)}" conditions << append_conditions(options, preload_options) associated_records = klass.find(:all, :conditions => [conditions, ids], :include => options[:include], :select => options[:select], :joins => options[:joins], :order => options[:order]) set_association_single_records(id_map, reflection.name, associated_records, primary_key) end end def find_associated_records(ids, reflection, preload_options) options = reflection.options table_name = reflection.klass.quoted_table_name if interface = reflection.options[:as] conditions = "#{reflection.klass.quoted_table_name}.#{connection.quote_column_name "#{interface}_id"} #{in_or_equals_for_ids(ids)} and #{reflection.klass.quoted_table_name}.#{connection.quote_column_name "#{interface}_type"} = '#{self.base_class.sti_name}'" else foreign_key = reflection.primary_key_name conditions = "#{reflection.klass.quoted_table_name}.#{foreign_key} #{in_or_equals_for_ids(ids)}" end conditions << append_conditions(options, preload_options) reflection.klass.find(:all, :select => (preload_options[:select] || options[:select] || "#{table_name}.*"), :include => preload_options[:include] || options[:include], :conditions => [conditions, ids], :joins => options[:joins], :group => preload_options[:group] || options[:group], :order => preload_options[:order] || options[:order]) end def interpolate_sql_for_preload(sql) instance_eval("%@#{sql.gsub('@', '\@')}@") end def append_conditions(options, preload_options) sql = "" sql << " AND (#{interpolate_sql_for_preload(sanitize_sql(options[:conditions]))})" if options[:conditions] sql << " AND (#{sanitize_sql preload_options[:conditions]})" if preload_options[:conditions] sql end def in_or_equals_for_ids(ids) ids.size > 1 ? "IN (?)" : "= ?" end end end end