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author | Jon Leighton <j@jonathanleighton.com> | 2010-11-27 11:31:17 +0000 |
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committer | Jon Leighton <j@jonathanleighton.com> | 2010-11-27 11:31:17 +0000 |
commit | 3a7f43ca6ecf1735e1a82d4a68ac8f62b5cf2fcf (patch) | |
tree | 4960911c58f2c47ecaf4f4579167270ba9c257a7 /activerecord/lib/active_record/associations/class_methods/join_dependency | |
parent | 1bc90044b655572a4b8aa3b323905e26d37e0f2b (diff) | |
parent | fd83f9d51583c080072dc9fd00f02ad742e265d4 (diff) | |
download | rails-3a7f43ca6ecf1735e1a82d4a68ac8f62b5cf2fcf.tar.gz rails-3a7f43ca6ecf1735e1a82d4a68ac8f62b5cf2fcf.tar.bz2 rails-3a7f43ca6ecf1735e1a82d4a68ac8f62b5cf2fcf.zip |
Merge branch 'master' into nested_has_many_through
Conflicts:
activerecord/CHANGELOG
activerecord/lib/active_record/associations.rb
Diffstat (limited to 'activerecord/lib/active_record/associations/class_methods/join_dependency')
3 files changed, 375 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations/class_methods/join_dependency/join_association.rb b/activerecord/lib/active_record/associations/class_methods/join_dependency/join_association.rb new file mode 100644 index 0000000000..ed2053d3df --- /dev/null +++ b/activerecord/lib/active_record/associations/class_methods/join_dependency/join_association.rb @@ -0,0 +1,261 @@ +module ActiveRecord + module Associations + module ClassMethods + 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 + + attr_reader :aliased_prefix + + delegate :options, :through_reflection, :source_reflection, :through_reflection_chain, :to => :reflection + delegate :table, :table_name, :to => :parent, :prefix => true + 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| + self.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.primary_key_name + when :has_many, :has_one + key = reflection.primary_key_name + 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.primary_key_name + 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.primary_key_name + + conditions << source_type_conditions(reflection, foreign_table) + when :has_many, :has_one + key = reflection.primary_key_name + foreign_key = reflection.source_reflection.active_record_primary_key + when :has_and_belongs_to_many + table, join_table = table + + join_key = reflection.primary_key_name + 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) + + relation = relation.join(table, join_type).on(*conditions.flatten.compact) + + # 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 + + def interpolate_sql(sql) + instance_eval("%@#{sql.gsub('@', '\@')}@", __FILE__, __LINE__) + 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| + aliased_table_name = alias_tracker.aliased_name_for( + reflection.table_name, + table_alias_for(reflection, reflection != self.reflection) + ) + + table = Arel::Table.new( + reflection.table_name, :engine => arel_engine, + :as => aliased_table_name, :columns => reflection.klass.columns + ) + + # 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_name = (reflection.source_reflection || reflection).options[:join_table] + + aliased_join_table_name = alias_tracker.aliased_name_for( + join_table_name, + table_alias_for(reflection, true) + ) + + join_table = Arel::Table.new( + join_table_name, :engine => arel_engine, + :as => aliased_join_table_name + ) + + [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! + + @tables + end + + def reflection_conditions(index, table) + @reflection.through_conditions.reverse[index].map do |condition| + Arel.sql(interpolate_sql(sanitize_sql( + 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] + + condition = sti_column.eq(reflection.klass.sti_name) + + reflection.klass.descendants.each do |subclass| + condition = condition.or(sti_column.eq(subclass.sti_name)) + end + + condition + end + end + + def source_type_conditions(reflection, foreign_table) + if reflection.options[:source_type] + foreign_table[reflection.source_reflection.options[:foreign_type]]. + eq(reflection.options[:source_type]) + end + end + + def polymorphic_conditions(reflection, table) + if reflection.options[:as] + table["#{reflection.options[:as]}_type"]. + eq(reflection.active_record.base_class.name) + end + end + end + end + end + end +end diff --git a/activerecord/lib/active_record/associations/class_methods/join_dependency/join_base.rb b/activerecord/lib/active_record/associations/class_methods/join_dependency/join_base.rb new file mode 100644 index 0000000000..ed05003f66 --- /dev/null +++ b/activerecord/lib/active_record/associations/class_methods/join_dependency/join_base.rb @@ -0,0 +1,34 @@ +module ActiveRecord + module Associations + module ClassMethods + class JoinDependency # :nodoc: + class JoinBase < JoinPart # :nodoc: + # Extra joins provided when the JoinDependency was created + attr_reader :table_joins + + def initialize(active_record, joins = nil) + super(active_record) + @table_joins = joins + end + + def ==(other) + other.class == self.class && + other.active_record == active_record + end + + def aliased_prefix + "t0" + end + + def table + Arel::Table.new(table_name, :engine => arel_engine, :columns => active_record.columns) + end + + def aliased_table_name + active_record.table_name + end + end + end + end + end +end diff --git a/activerecord/lib/active_record/associations/class_methods/join_dependency/join_part.rb b/activerecord/lib/active_record/associations/class_methods/join_dependency/join_part.rb new file mode 100644 index 0000000000..0b093b65e9 --- /dev/null +++ b/activerecord/lib/active_record/associations/class_methods/join_dependency/join_part.rb @@ -0,0 +1,80 @@ +module ActiveRecord + module Associations + module ClassMethods + 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, :sanitize_sql, :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 +end |