Module | Sequel::Plugins::DatasetAssociations::DatasetMethods |
In: |
lib/sequel/plugins/dataset_associations.rb
|
For the association given by name, return a dataset of associated objects such that it would return the union of calling the association method on all objects returned by the current dataset.
This supports most options that are supported when eager loading. It doesn‘t support limits on the associations, or one_to_one associations that are really one_to_many and use an order to select the first matching object. In both of those cases, this will return an array of all matching objects.
# File lib/sequel/plugins/dataset_associations.rb, line 71 71: def associated(name) 72: raise Error, "unrecognized association name: #{name.inspect}" unless r = model.association_reflection(name) 73: ds = r.associated_class.dataset 74: sds = opts[:limit] ? self : unordered 75: ds = case r[:type] 76: when :many_to_one 77: ds.filter(r.qualified_primary_key=>sds.select(*Array(r[:qualified_key]))) 78: when :one_to_one, :one_to_many 79: ds.filter(r.qualified_key=>sds.select(*Array(r.qualified_primary_key))) 80: when :many_to_many 81: ds.filter(r.qualified_right_primary_key=>sds.select(*Array(r.qualified_right_key)). 82: join(r[:join_table], r[:left_keys].zip(r[:left_primary_keys]), :implicit_qualifier=>model.table_name)) 83: when :many_through_many 84: fre = r.reverse_edges.first 85: fe, *edges = r.edges 86: sds = sds.select(*Array(r.qualify(fre[:table], fre[:left]))). 87: join(fe[:table], Array(fe[:right]).zip(Array(fe[:left])), :implicit_qualifier=>model.table_name) 88: edges.each{|e| sds = sds.join(e[:table], Array(e[:right]).zip(Array(e[:left])))} 89: ds.filter(r.qualified_right_primary_key=>sds) 90: else 91: raise Error, "unrecognized association type for association #{name.inspect}: #{r[:type].inspect}" 92: end 93: ds = model.apply_association_dataset_opts(r, ds) 94: r[:extend].each{|m| ds.extend(m)} 95: ds 96: end