lib/similar_models.rb in similar_models-0.1.0 vs lib/similar_models.rb in similar_models-0.2.0

@@ -6,34 +6,33 @@
     as = "similar_#{model_name.plural}" unless as
 
     # defaults to 'def similar_{model name}'
     define_method as do
       table_name = self.class.table_name
+      primary_key = self.class.primary_key
+      primary_key_ref = "#{table_name}.#{primary_key}"
       association_scopes = []
 
       many_to_many_associations.each do |many_to_many_association|
         assocation = self.class.reflect_on_association(many_to_many_association)
         join_table, foreign_key, association_foreign_key = self.class.join_table_values(assocation)
 
-        association_scopes << self.class.where("#{join_table}.#{association_foreign_key} IN " +
-          "(select #{join_table}.#{association_foreign_key} from #{join_table} " +
-          "where #{join_table}.#{foreign_key} = :foreign_key)", foreign_key: self.id).
-          joins("INNER JOIN #{join_table} ON #{join_table}.#{foreign_key} = #{table_name}.id")
+        association_scopes << self.class.where(
+          "#{join_table}.#{association_foreign_key} IN \
+          (select #{join_table}.#{association_foreign_key} from #{join_table} \
+          where #{join_table}.#{foreign_key} = :foreign_key)", foreign_key: self.id
+        ).joins("INNER JOIN #{join_table} ON #{join_table}.#{foreign_key} = #{primary_key_ref}")
       end
 
-      scope = self.class.select("#{table_name}.*, count(#{table_name}.id) AS #{as}_model_count").
-        where.not(id: self.id).order("#{as}_model_count DESC")
-      group_by_clause = 'id'
+      scope = self.class.select("#{table_name}.*, count(#{primary_key_ref}) AS #{as}_model_count").
+        where.not(primary_key => self.id).order("#{as}_model_count DESC")
+      group_by_clause = primary_key
 
       # if there is only one many-to-many association no need to use UNION sql syntax
       if association_scopes.one?
         scope.merge(association_scopes.first).group(group_by_clause)
       else
-        # with postgres the group by clause has to be different
-        # http://dba.stackexchange.com/questions/88988/postgres-error-column-must-appear-in-the-group-by-clause-or-be-used-in-an-aggre
-        if ActiveRecord::Base.connection.adapter_name == 'PostgreSQL'
-          group_by_clause = self.class.column_names.join(', ')
-        end
+        group_by_clause = self.class.column_names.join(', ')
 
         # see http://blog.ubersense.com/2013/09/27/tech-talk-unioning-scoped-queries-in-rails/
         scope.from("((#{association_scopes.map(&:to_sql).join(') UNION ALL (')})) AS #{table_name}").group(group_by_clause)
       end
     end