diff options
Diffstat (limited to 'activerecord/lib/active_record/associations/join_dependency/join_association.rb')
| -rw-r--r-- | activerecord/lib/active_record/associations/join_dependency/join_association.rb | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations/join_dependency/join_association.rb b/activerecord/lib/active_record/associations/join_dependency/join_association.rb new file mode 100644 index 0000000000..890e77fca9 --- /dev/null +++ b/activerecord/lib/active_record/associations/join_dependency/join_association.rb @@ -0,0 +1,259 @@ +module ActiveRecord + module Associations + class JoinDependency # :nodoc: + class JoinAssociation < JoinPart # :nodoc: + # The reflection of the association represented + attr_reader :reflection + + # The JoinDependency object which this JoinAssociation exists within. This is mainly + # relevant for generating aliases which do not conflict with other joins which are + # part of the query. + attr_reader :join_dependency + + # A JoinBase instance representing the active record we are joining onto. + # (So in Author.has_many :posts, the Author would be that base record.) + attr_reader :parent + + # What type of join will be generated, either Arel::InnerJoin (default) or Arel::OuterJoin + attr_accessor :join_type + + # These implement abstract methods from the superclass + attr_reader :aliased_prefix + + attr_reader :tables + + delegate :options, :through_reflection, :source_reflection, :through_reflection_chain, :to => :reflection + delegate :table, :table_name, :to => :parent, :prefix => :parent + delegate :alias_tracker, :to => :join_dependency + + def initialize(reflection, join_dependency, parent = nil) + reflection.check_validity! + + if reflection.options[:polymorphic] + raise EagerLoadPolymorphicError.new(reflection) + end + + super(reflection.klass) + + @reflection = reflection + @join_dependency = join_dependency + @parent = parent + @join_type = Arel::InnerJoin + @aliased_prefix = "t#{ join_dependency.join_parts.size }" + + setup_tables + end + + def ==(other) + other.class == self.class && + other.reflection == reflection && + other.parent == parent + end + + def find_parent_in(other_join_dependency) + other_join_dependency.join_parts.detect do |join_part| + parent == join_part + end + end + + def join_to(relation) + # The chain starts with the target table, but we want to end with it here (makes + # more sense in this context) + chain = through_reflection_chain.reverse + + foreign_table = parent_table + index = 0 + + chain.each do |reflection| + table = tables[index] + conditions = [] + + if reflection.source_reflection.nil? + case reflection.macro + when :belongs_to + key = reflection.association_primary_key + foreign_key = reflection.foreign_key + when :has_many, :has_one + key = reflection.foreign_key + foreign_key = reflection.active_record_primary_key + + conditions << polymorphic_conditions(reflection, table) + when :has_and_belongs_to_many + # For habtm, we need to deal with the join table at the same time as the + # target table (because unlike a :through association, there is no reflection + # to represent the join table) + table, join_table = table + + join_key = reflection.foreign_key + join_foreign_key = reflection.active_record.primary_key + + relation = relation.join(join_table, join_type).on( + join_table[join_key]. + eq(foreign_table[join_foreign_key]) + ) + + # We've done the first join now, so update the foreign_table for the second + foreign_table = join_table + + key = reflection.klass.primary_key + foreign_key = reflection.association_foreign_key + end + else + case reflection.source_reflection.macro + when :belongs_to + key = reflection.association_primary_key + foreign_key = reflection.foreign_key + + conditions << source_type_conditions(reflection, foreign_table) + when :has_many, :has_one + key = reflection.foreign_key + foreign_key = reflection.source_reflection.active_record_primary_key + when :has_and_belongs_to_many + table, join_table = table + + join_key = reflection.foreign_key + join_foreign_key = reflection.klass.primary_key + + relation = relation.join(join_table, join_type).on( + join_table[join_key]. + eq(foreign_table[join_foreign_key]) + ) + + foreign_table = join_table + + key = reflection.klass.primary_key + foreign_key = reflection.association_foreign_key + end + end + + conditions << table[key].eq(foreign_table[foreign_key]) + + conditions << reflection_conditions(index, table) + conditions << sti_conditions(reflection, table) + + ands = relation.create_and(conditions.flatten.compact) + + join = relation.create_join( + table, + relation.create_on(ands), + join_type) + + relation = relation.from(join) + + # The current table in this iteration becomes the foreign table in the next + foreign_table = table + index += 1 + end + + relation + end + + def join_relation(joining_relation) + self.join_type = Arel::OuterJoin + joining_relation.joins(self) + end + + def table + if tables.last.is_a?(Array) + tables.last.first + else + tables.last + end + end + + def aliased_table_name + table.table_alias || table.name + end + + protected + + def table_alias_for(reflection, join = false) + name = alias_tracker.pluralize(reflection.name) + name << "_#{parent_table_name}" + name << "_join" if join + name + end + + private + + # Generate aliases and Arel::Table instances for each of the tables which we will + # later generate joins for. We must do this in advance in order to correctly allocate + # the proper alias. + def setup_tables + @tables = through_reflection_chain.map do |reflection| + table = alias_tracker.aliased_table_for( + reflection.table_name, + table_alias_for(reflection, reflection != self.reflection) + ) + + # For habtm, we have two Arel::Table instances related to a single reflection, so + # we just store them as a pair in the array. + if reflection.macro == :has_and_belongs_to_many || + (reflection.source_reflection && reflection.source_reflection.macro == :has_and_belongs_to_many) + + join_table = alias_tracker.aliased_table_for( + (reflection.source_reflection || reflection).options[:join_table], + table_alias_for(reflection, true) + ) + + [table, join_table] + else + table + end + end + + # The joins are generated from the through_reflection_chain in reverse order, so + # reverse the tables too (but it's important to generate the aliases in the 'forward' + # order, which is why we only do the reversal now. + @tables.reverse! + end + + def process_conditions(conditions, table_name) + if conditions.respond_to?(:to_proc) + conditions = instance_eval(&conditions) + end + + Arel.sql(sanitize_sql(conditions, table_name)) + end + + def sanitize_sql(condition, table_name) + active_record.send(:sanitize_sql, condition, table_name) + end + + def reflection_conditions(index, table) + reflection.through_conditions.reverse[index].map do |condition| + process_conditions(condition, table.table_alias || table.name) + end + end + + def sti_conditions(reflection, table) + unless reflection.klass.descends_from_active_record? + sti_column = table[reflection.klass.inheritance_column] + sti_condition = sti_column.eq(reflection.klass.sti_name) + subclasses = reflection.klass.descendants + + # TODO: use IN (...), or possibly AR::Base#type_condition + subclasses.inject(sti_condition) { |attr,subclass| + attr.or(sti_column.eq(subclass.sti_name)) + } + end + end + + def source_type_conditions(reflection, foreign_table) + if reflection.options[:source_type] + foreign_table[reflection.source_reflection.foreign_type]. + eq(reflection.options[:source_type]) + end + end + + def polymorphic_conditions(reflection, table) + if reflection.options[:as] + table[reflection.type]. + eq(reflection.active_record.base_class.name) + end + end + + end + end + end +end |