diff options
Diffstat (limited to 'activerecord/lib/active_record/associations/join_dependency')
3 files changed, 381 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..ebe39c35fe --- /dev/null +++ b/activerecord/lib/active_record/associations/join_dependency/join_association.rb @@ -0,0 +1,279 @@ +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, :aliased_table_name + + delegate :options, :through_reflection, :source_reflection, :to => :reflection + delegate :table, :table_name, :to => :parent, :prefix => :parent + + 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 }" + + # This must be done eagerly upon initialisation because the alias which is produced + # depends on the state of the join dependency, but we want it to work the same way + # every time. + allocate_aliases + @table = Arel::Table.new( + table_name, :as => aliased_table_name, :engine => arel_engine + ) + 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) + send("join_#{reflection.macro}_to", relation) + end + + def join_relation(joining_relation) + self.join_type = Arel::OuterJoin + joining_relation.joins(self) + end + + attr_reader :table + # More semantic name given we are talking about associations + alias_method :target_table, :table + + protected + + def aliased_table_name_for(name, suffix = nil) + aliases = @join_dependency.table_aliases + + if aliases[name] != 0 # We need an alias + connection = active_record.connection + + name = connection.table_alias_for "#{pluralize(reflection.name)}_#{parent_table_name}#{suffix}" + aliases[name] += 1 + name = name[0, connection.table_alias_length-3] + "_#{aliases[name]}" if aliases[name] > 1 + else + aliases[name] += 1 + end + + name + end + + def pluralize(table_name) + ActiveRecord::Base.pluralize_table_names ? table_name.to_s.pluralize : table_name + end + + private + + def allocate_aliases + @aliased_table_name = aliased_table_name_for(table_name) + + if reflection.macro == :has_and_belongs_to_many + @aliased_join_table_name = aliased_table_name_for(reflection.options[:join_table], "_join") + elsif [:has_many, :has_one].include?(reflection.macro) && reflection.options[:through] + @aliased_join_table_name = aliased_table_name_for(reflection.through_reflection.klass.table_name, "_join") + end + 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 join_target_table(relation, condition) + conditions = [condition] + + # If the target table is an STI model then we must be sure to only include records of + # its type and its sub-types. + unless active_record.descends_from_active_record? + sti_column = target_table[active_record.inheritance_column] + subclasses = active_record.descendants + sti_condition = sti_column.eq(active_record.sti_name) + + conditions << subclasses.inject(sti_condition) { |attr,subclass| + attr.or(sti_column.eq(subclass.sti_name)) + } + end + + # If the reflection has conditions, add them + if options[:conditions] + conditions << process_conditions(options[:conditions], aliased_table_name) + end + + ands = relation.create_and(conditions) + + join = relation.create_join( + target_table, + relation.create_on(ands), + join_type) + + relation.from join + end + + def join_has_and_belongs_to_many_to(relation) + join_table = Arel::Table.new( + options[:join_table] + ).alias(@aliased_join_table_name) + + fk = options[:foreign_key] || reflection.active_record.to_s.foreign_key + klass_fk = options[:association_foreign_key] || reflection.klass.to_s.foreign_key + + relation = relation.join(join_table, join_type) + relation = relation.on( + join_table[fk]. + eq(parent_table[reflection.active_record.primary_key]) + ) + + join_target_table( + relation, + target_table[reflection.klass.primary_key]. + eq(join_table[klass_fk]) + ) + end + + def join_has_many_to(relation) + if reflection.options[:through] + join_has_many_through_to(relation) + elsif reflection.options[:as] + join_has_many_polymorphic_to(relation) + else + foreign_key = options[:foreign_key] || reflection.active_record.name.foreign_key + primary_key = options[:primary_key] || parent.primary_key + + join_target_table( + relation, + target_table[foreign_key]. + eq(parent_table[primary_key]) + ) + end + end + alias :join_has_one_to :join_has_many_to + + def join_has_many_through_to(relation) + join_table = Arel::Table.new( + through_reflection.klass.table_name + ).alias @aliased_join_table_name + + jt_conditions = [] + first_key = second_key = nil + + if through_reflection.macro == :belongs_to + jt_primary_key = through_reflection.foreign_key + jt_foreign_key = through_reflection.association_primary_key + else + jt_primary_key = through_reflection.active_record_primary_key + jt_foreign_key = through_reflection.foreign_key + + if through_reflection.options[:as] # has_many :through against a polymorphic join + jt_conditions << + join_table["#{through_reflection.options[:as]}_type"]. + eq(parent.active_record.base_class.name) + end + end + + case source_reflection.macro + when :has_many + second_key = options[:foreign_key] || primary_key + + if source_reflection.options[:as] + first_key = "#{source_reflection.options[:as]}_id" + else + first_key = through_reflection.klass.base_class.to_s.foreign_key + end + + unless through_reflection.klass.descends_from_active_record? + jt_conditions << + join_table[through_reflection.active_record.inheritance_column]. + eq(through_reflection.klass.sti_name) + end + when :belongs_to + first_key = primary_key + + if reflection.options[:source_type] + second_key = source_reflection.association_foreign_key + + jt_conditions << + join_table[reflection.source_reflection.foreign_type]. + eq(reflection.options[:source_type]) + else + second_key = source_reflection.foreign_key + end + end + + jt_conditions << + parent_table[jt_primary_key]. + eq(join_table[jt_foreign_key]) + + if through_reflection.options[:conditions] + jt_conditions << process_conditions(through_reflection.options[:conditions], aliased_table_name) + end + + relation = relation.join(join_table, join_type).on(*jt_conditions) + + join_target_table( + relation, + target_table[first_key].eq(join_table[second_key]) + ) + end + + def join_has_many_polymorphic_to(relation) + join_target_table( + relation, + target_table["#{reflection.options[:as]}_id"]. + eq(parent_table[parent.primary_key]).and( + target_table["#{reflection.options[:as]}_type"]. + eq(parent.active_record.base_class.name)) + ) + end + + def join_belongs_to_to(relation) + foreign_key = options[:foreign_key] || reflection.foreign_key + primary_key = options[:primary_key] || reflection.klass.primary_key + + join_target_table( + relation, + target_table[primary_key].eq(parent_table[foreign_key]) + ) + end + end + end + end +end diff --git a/activerecord/lib/active_record/associations/join_dependency/join_base.rb b/activerecord/lib/active_record/associations/join_dependency/join_base.rb new file mode 100644 index 0000000000..3920e84976 --- /dev/null +++ b/activerecord/lib/active_record/associations/join_dependency/join_base.rb @@ -0,0 +1,24 @@ +module ActiveRecord + module Associations + class JoinDependency # :nodoc: + class JoinBase < JoinPart # :nodoc: + def ==(other) + other.class == self.class && + other.active_record == active_record + end + + def aliased_prefix + "t0" + end + + def table + Arel::Table.new(table_name, arel_engine) + end + + def aliased_table_name + active_record.table_name + end + end + end + end +end diff --git a/activerecord/lib/active_record/associations/join_dependency/join_part.rb b/activerecord/lib/active_record/associations/join_dependency/join_part.rb new file mode 100644 index 0000000000..3279e56e7d --- /dev/null +++ b/activerecord/lib/active_record/associations/join_dependency/join_part.rb @@ -0,0 +1,78 @@ +module ActiveRecord + module Associations + class JoinDependency # :nodoc: + # A JoinPart represents a part of a JoinDependency. It is an abstract class, inherited + # by JoinBase and JoinAssociation. A JoinBase represents the Active Record which + # everything else is being joined onto. A JoinAssociation represents an association which + # is joining to the base. A JoinAssociation may result in more than one actual join + # operations (for example a has_and_belongs_to_many JoinAssociation would result in + # two; one for the join table and one for the target table). + class JoinPart # :nodoc: + # The Active Record class which this join part is associated 'about'; for a JoinBase + # this is the actual base model, for a JoinAssociation this is the target model of the + # association. + attr_reader :active_record + + delegate :table_name, :column_names, :primary_key, :reflections, :arel_engine, :to => :active_record + + def initialize(active_record) + @active_record = active_record + @cached_record = {} + @column_names_with_alias = nil + end + + def aliased_table + Arel::Nodes::TableAlias.new aliased_table_name, table + end + + def ==(other) + raise NotImplementedError + end + + # An Arel::Table for the active_record + def table + raise NotImplementedError + end + + # The prefix to be used when aliasing columns in the active_record's table + def aliased_prefix + raise NotImplementedError + end + + # The alias for the active_record's table + def aliased_table_name + raise NotImplementedError + end + + # The alias for the primary key of the active_record's table + def aliased_primary_key + "#{aliased_prefix}_r0" + end + + # An array of [column_name, alias] pairs for the table + def column_names_with_alias + unless @column_names_with_alias + @column_names_with_alias = [] + + ([primary_key] + (column_names - [primary_key])).each_with_index do |column_name, i| + @column_names_with_alias << [column_name, "#{aliased_prefix}_r#{i}"] + end + end + @column_names_with_alias + end + + def extract_record(row) + Hash[column_names_with_alias.map{|cn, an| [cn, row[an]]}] + end + + def record_id(row) + row[aliased_primary_key] + end + + def instantiate(row) + @cached_record[record_id(row)] ||= active_record.send(:instantiate, extract_record(row)) + end + end + end + end +end |