module Sequel::Plugins::ManyThroughMany::ClassMethods
Public Instance Methods
Create a #many_through_many association. Arguments:
-
name - Same as associate, the name of the association.
-
through - The tables and keys to join between the current table and the associated table. Must be an array, with elements that are either 3 element arrays, or hashes with keys :table, :left, and :right. The required entries in the array/hash are:
- :table (first array element)
-
The name of the table to join.
- :left (middle array element)
-
The key joining the table to the previous table. Can use an array of symbols for a composite key association.
- :right (last array element)
-
The key joining the table to the next table. Can use an array of symbols for a composite key association.
If a hash is provided, the following keys are respected when using eager_graph:
- :block
-
A proc to use as the block argument to join.
- :conditions
-
Extra conditions to add to the JOIN ON clause. Must be a hash or array of two pairs.
- :join_type
-
The join type to use for the join, defaults to :left_outer.
- :only_conditions
-
Conditions to use for the join instead of the ones specified by the keys.
-
opts - The options for the associaion. Takes the same options as many_to_many.
# File lib/sequel/plugins/many_through_many.rb, line 160 def many_through_many(name, through, opts={}, &block) associate(:many_through_many, name, opts.merge(through.is_a?(Hash) ? through : {:through=>through}), &block) end
Private Instance Methods
Create the association methods and :eager_loader and :eager_grapher procs.
# File lib/sequel/plugins/many_through_many.rb, line 167 def def_many_through_many(opts) name = opts[:name] model = self opts[:read_only] = true opts[:after_load].unshift(:array_uniq!) if opts[:uniq] opts[:cartesian_product_number] ||= 2 opts[:through] = opts[:through].map do |e| case e when Array raise(Error, "array elements of the through option/argument for many_through_many associations must have at least three elements") unless e.length == 3 {:table=>e[0], :left=>e[1], :right=>e[2]} when Hash raise(Error, "hash elements of the through option/argument for many_through_many associations must contain :table, :left, and :right keys") unless e[:table] && e[:left] && e[:right] e else raise(Error, "the through option/argument for many_through_many associations must be an enumerable of arrays or hashes") end end left_key = opts[:left_key] = opts[:through].first[:left] uses_lcks = opts[:uses_left_composite_keys] = left_key.is_a?(Array) left_keys = Array(left_key) left_pk = (opts[:left_primary_key] ||= self.primary_key) opts[:eager_loader_key] = left_pk unless opts.has_key?(:eager_loader_key) left_pks = opts[:left_primary_keys] = Array(left_pk) lpkc = opts[:left_primary_key_column] ||= left_pk opts[:left_primary_key_columns] ||= Array(lpkc) opts[:dataset] ||= lambda do ds = opts.associated_dataset opts.reverse_edges.each{|t| ds = ds.join(t[:table], Array(t[:left]).zip(Array(t[:right])), :table_alias=>t[:alias], :qualify=>:deep)} ft = opts.final_reverse_edge ds.join(ft[:table], Array(ft[:left]).zip(Array(ft[:right])) + opts.predicate_keys.zip(left_pks.map{|k| send(k)}), :table_alias=>ft[:alias], :qualify=>:deep) end left_key_alias = opts[:left_key_alias] ||= opts.default_associated_key_alias opts[:eager_loader] ||= lambda do |eo| h = eo[:id_map] rows = eo[:rows] rows.each{|object| object.associations[name] = []} ds = opts.associated_class opts.reverse_edges.each{|t| ds = ds.join(t[:table], Array(t[:left]).zip(Array(t[:right])), :table_alias=>t[:alias], :qualify=>:deep)} ft = opts.final_reverse_edge ds = ds.join(ft[:table], Array(ft[:left]).zip(Array(ft[:right])) + [[opts.predicate_key, h.keys]], :table_alias=>ft[:alias], :qualify=>:deep) ds = model.eager_loading_dataset(opts, ds, nil, eo[:associations], eo) case opts.eager_limit_strategy when :window_function delete_rn = true rn = ds.row_number_column ds = apply_window_function_eager_limit_strategy(ds, opts) when :correlated_subquery ds = apply_correlated_subquery_eager_limit_strategy(ds, opts) do |xds| dsa = ds.send(:dataset_alias, 2) opts.reverse_edges.each{|t| xds = xds.join(t[:table], Array(t[:left]).zip(Array(t[:right])), :table_alias=>t[:alias])} xds.join(ft[:table], Array(ft[:left]).zip(Array(ft[:right])) + left_keys.map{|k| [k, SQL::QualifiedIdentifier.new(ft[:table], k)]}, :table_alias=>dsa, :qualify=>:deep) end end ds.all do |assoc_record| assoc_record.values.delete(rn) if delete_rn hash_key = if uses_lcks left_key_alias.map{|k| assoc_record.values.delete(k)} else assoc_record.values.delete(left_key_alias) end next unless objects = h[hash_key] objects.each{|object| object.associations[name].push(assoc_record)} end if opts.eager_limit_strategy == :ruby limit, offset = opts.limit_and_offset rows.each{|o| o.associations[name] = o.associations[name].slice(offset||0, limit) || []} end end join_type = opts[:graph_join_type] select = opts[:graph_select] graph_block = opts[:graph_block] only_conditions = opts[:graph_only_conditions] use_only_conditions = opts.include?(:graph_only_conditions) conditions = opts[:graph_conditions] opts[:eager_grapher] ||= proc do |eo| ds = eo[:self] iq = eo[:implicit_qualifier] opts.edges.each do |t| ds = ds.graph(t[:table], t.fetch(:only_conditions, (Array(t[:right]).zip(Array(t[:left])) + t[:conditions])), :select=>false, :table_alias=>ds.unused_table_alias(t[:table]), :join_type=>t[:join_type], :qualify=>:deep, :implicit_qualifier=>iq, &t[:block]) iq = nil end fe = opts.final_edge ds.graph(opts.associated_class, use_only_conditions ? only_conditions : (Array(opts.right_primary_key).zip(Array(fe[:left])) + conditions), :select=>select, :table_alias=>eo[:table_alias], :qualify=>:deep, :join_type=>join_type, &graph_block) end def_association_dataset_methods(opts) end