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author | Gonçalo Silva <goncalossilva@gmail.com> | 2011-03-24 17:21:17 +0000 |
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committer | Gonçalo Silva <goncalossilva@gmail.com> | 2011-03-24 17:21:17 +0000 |
commit | 9887f238871bb2dd73de6ce8855615bcc5d8d079 (patch) | |
tree | 74fa9ff9524a51701cfa23f708b3f777c65b7fe5 /activerecord/lib/active_record/associations/preloader/has_and_belongs_to_many.rb | |
parent | aff821508a16245ebc03510ba29c70379718dfb7 (diff) | |
parent | 5214e73850916de3c9127d35a4ecee0424d364a3 (diff) | |
download | rails-9887f238871bb2dd73de6ce8855615bcc5d8d079.tar.gz rails-9887f238871bb2dd73de6ce8855615bcc5d8d079.tar.bz2 rails-9887f238871bb2dd73de6ce8855615bcc5d8d079.zip |
Merge branch 'master' of https://github.com/rails/rails
Diffstat (limited to 'activerecord/lib/active_record/associations/preloader/has_and_belongs_to_many.rb')
-rw-r--r-- | activerecord/lib/active_record/associations/preloader/has_and_belongs_to_many.rb | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations/preloader/has_and_belongs_to_many.rb b/activerecord/lib/active_record/associations/preloader/has_and_belongs_to_many.rb new file mode 100644 index 0000000000..24be279449 --- /dev/null +++ b/activerecord/lib/active_record/associations/preloader/has_and_belongs_to_many.rb @@ -0,0 +1,60 @@ +module ActiveRecord + module Associations + class Preloader + class HasAndBelongsToMany < CollectionAssociation #:nodoc: + attr_reader :join_table + + def initialize(klass, records, reflection, preload_options) + super + @join_table = Arel::Table.new(options[:join_table]).alias('t0') + end + + # Unlike the other associations, we want to get a raw array of rows so that we can + # access the aliased column on the join table + def records_for(ids) + scope = super + klass.connection.select_all(scope.arel.to_sql, 'SQL', scope.bind_values) + end + + def owner_key_name + reflection.active_record_primary_key + end + + def association_key_name + 'ar_association_key_name' + end + + def association_key + join_table[reflection.foreign_key] + end + + private + + # Once we have used the join table column (in super), we manually instantiate the + # actual records, ensuring that we don't create more than one instances of the same + # record + def associated_records_by_owner + records = {} + super.each do |owner_key, rows| + rows.map! { |row| records[row[klass.primary_key]] ||= klass.instantiate(row) } + end + end + + def build_scope + super.joins(join).select(join_select) + end + + def join_select + association_key.as(Arel.sql(association_key_name)) + end + + def join + condition = table[reflection.association_primary_key].eq( + join_table[reflection.association_foreign_key]) + + table.create_join(join_table, table.create_on(condition)) + end + end + end + end +end |