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module Sequel
module Plugins
# The association_pks plugin adds the association_pks and association_pks=
# instance methods to the model class for each association added. These
# methods allow for easily returning the primary keys of the associated
# objects, and easily modifying the associated objects to set the primary
# keys to just the ones given:
#
# Artist.one_to_many :albums
# artist = Artist[1]
# artist.album_pks # [1, 2, 3]
# artist.album_pks = [2, 4]
# artist.album_pks # [2, 4]
#
# Note that it uses the singular form of the association name. Also note
# that the setter both associates to new primary keys not in the assocation
# and disassociates from primary keys not provided to the method.
#
# This plugin makes modifications directly to the underlying tables,
# it does not create or return any model objects, and therefore does
# not call any callbacks. If you have any association callbacks,
# you probably should not use the setter methods.
#
# This plugin only works with singular primary keys, it does not work
# with composite primary keys.
#
# Usage:
#
# # Make all model subclass *_to_many associations have association_pks
# # methods (called before loading subclasses)
# Sequel::Model.plugin :association_pks
#
# # Make the Album *_to_many associations have association_pks
# # methods (called before the association methods)
# Album.plugin :association_pks
module AssociationPks
module ClassMethods
private
# Define a association_pks method using the block for the association reflection
def def_association_pks_getter(opts, &block)
association_module_def(:"#{singularize(opts[:name])}_pks", opts, &block)
end
# Define a association_pks= method using the block for the association reflection,
# if the association is not read only.
def def_association_pks_setter(opts, &block)
association_module_def(:"#{singularize(opts[:name])}_pks=", opts, &block) unless opts[:read_only]
end
# Add a getter that checks the join table for matching records and
# a setter that deletes from or inserts into the join table.
def def_many_to_many(opts)
super
def_association_pks_getter(opts) do
_join_table_dataset(opts).filter(opts[:left_key]=>send(opts[:left_primary_key])).select_map(opts[:right_key])
end
def_association_pks_setter(opts) do |pks|
pks = convert_pk_array(opts, pks)
checked_transaction do
ds = _join_table_dataset(opts).filter(opts[:left_key]=>send(opts[:left_primary_key]))
ds.exclude(opts[:right_key]=>pks).delete
pks -= ds.select_map(opts[:right_key])
pks.each do |pk|
insert = Hash[Array(opts[:right_key]).zip(Array(pk))]
insert[opts[:left_key]] = send(opts[:left_primary_key])
ds.insert(insert)
end
end
end
end
# Add a getter that checks the association dataset and a setter
# that updates the associated table.
def def_one_to_many(opts)
super
return if opts[:type] == :one_to_one
def_association_pks_getter(opts) do
send(opts.dataset_method).select_map(opts.associated_class.primary_key)
end
def_association_pks_setter(opts) do |pks|
pks = convert_pk_array(opts, pks)
checked_transaction do
ds = send(opts.dataset_method)
primary_key = opts.associated_class.primary_key
key = opts[:key]
ds.unfiltered.filter(primary_key=>pks).update(key=>pk)
ds.exclude(primary_key=>pks).update(key=>nil)
end
end
end
end
module InstanceMethods
private
# If the associated class's primary key column type is integer,
# typecast all provided values to integer before using them.
def convert_pk_array(opts, pks)
if klass = opts.associated_class and sch = klass.db_schema and col = sch[klass.primary_key] and col[:type] == :integer
pks.map{|pk| model.db.typecast_value(:integer, pk)}
else
pks
end
end
end
end
end
end
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