class Sequel::Plugins::ManyThroughMany::ManyThroughManyAssociationReflection

The AssociationReflection subclass for many_through_many associations.

Constants

FINALIZE_SETTINGS

Public Instance Methods

cloneable?(ref) click to toggle source

many_through_many and one_through_many associations can be clones

   # File lib/sequel/plugins/many_through_many.rb
87 def cloneable?(ref)
88   ref[:type] == :many_through_many || ref[:type] == :one_through_many
89 end
default_associated_key_alias() click to toggle source

The default associated key alias(es) to use when eager loading associations via eager.

   # File lib/sequel/plugins/many_through_many.rb
93 def default_associated_key_alias
94   self[:uses_left_composite_keys] ? (0...self[:through].first[:left].length).map{|i| :"x_foreign_key_#{i}_x"} : :x_foreign_key_x
95 end
finalize_settings() click to toggle source
    # File lib/sequel/plugins/many_through_many.rb
112 def finalize_settings
113   FINALIZE_SETTINGS
114 end
join_table_alias() click to toggle source

The alias for the first join table.

    # File lib/sequel/plugins/many_through_many.rb
117 def join_table_alias
118   final_reverse_edge[:alias]
119 end
reciprocal() click to toggle source

Many through many associations don't have a reciprocal

    # File lib/sequel/plugins/many_through_many.rb
122 def reciprocal
123   nil
124 end

Private Instance Methods

_associated_dataset() click to toggle source
    # File lib/sequel/plugins/many_through_many.rb
128 def _associated_dataset
129   ds = associated_class
130   (reverse_edges + [final_reverse_edge]).each do |t|
131     h = {:qualify=>:deep}
132     if t[:alias] != t[:table]
133       h[:table_alias] = t[:alias]
134     end
135     ds = ds.join(t[:table], Array(t[:left]).zip(Array(t[:right])), h)
136   end
137   ds
138 end
calculate_edges() click to toggle source

Transform the :through option into a list of edges and reverse edges to use to join tables when loading the association.

    # File lib/sequel/plugins/many_through_many.rb
158 def calculate_edges
159   es = [{:left_table=>self[:model].table_name, :left_key=>self[:left_primary_key_column]}]
160   self[:through].each do |t|
161     es.last.merge!(:right_key=>t[:left], :right_table=>t[:table], :join_type=>t[:join_type]||self[:graph_join_type], :conditions=>(t[:conditions]||[]).to_a, :block=>t[:block])
162     es.last[:only_conditions] = t[:only_conditions] if t.include?(:only_conditions)
163     es << {:left_table=>t[:table], :left_key=>t[:right]}
164   end
165   es.last.merge!(:right_key=>right_primary_key, :right_table=>associated_class.table_name)
166   edges = es.map do |e| 
167     h = {:table=>e[:right_table], :left=>e[:left_key], :right=>e[:right_key], :conditions=>e[:conditions], :join_type=>e[:join_type], :block=>e[:block]}
168     h[:only_conditions] = e[:only_conditions] if e.include?(:only_conditions)
169     h
170   end
171   reverse_edges = es.reverse.map{|e| {:table=>e[:left_table], :left=>e[:left_key], :right=>e[:right_key]}}
172   reverse_edges.pop
173   calculate_reverse_edge_aliases(reverse_edges)
174   final_reverse_edge = reverse_edges.pop
175   final_reverse_alias = final_reverse_edge[:alias]
176 
177   h = {:final_edge=>edges.pop,
178        :final_reverse_edge=>final_reverse_edge,
179        :edges=>edges,
180        :reverse_edges=>reverse_edges,
181        :predicate_key=>qualify(final_reverse_alias, edges.first[:right]),
182        :associated_key_table=>final_reverse_edge[:alias],
183   }
184   h.each{|k, v| cached_set(k, v)}
185   h
186 end
calculate_reverse_edge_aliases(reverse_edges) click to toggle source

Make sure to use unique table aliases when lazy loading or eager loading

    # File lib/sequel/plugins/many_through_many.rb
141 def calculate_reverse_edge_aliases(reverse_edges)
142   aliases = [associated_class.table_name]
143   reverse_edges.each do |e|
144     table_alias = e[:table]
145     if aliases.include?(table_alias)
146       i = 0
147       table_alias = while true
148         ta = :"#{table_alias}_#{i}"
149         break ta unless aliases.include?(ta)
150         i += 1
151       end
152     end
153     aliases.push(e[:alias] = table_alias)
154   end
155 end
filter_by_associations_limit_key() click to toggle source
    # File lib/sequel/plugins/many_through_many.rb
188 def filter_by_associations_limit_key
189   fe = edges.first
190   Array(qualify(fe[:table], fe[:right])) + Array(qualify(associated_class.table_name, associated_class.primary_key))
191 end