Fixes Issue #91: SystemStackError when using .with (#105)

Signed-off-by: Garrett Blehm <[email protected]>

lib/active_record_extended/query_methods/with_cte.rb

@@ -54,6 +54,8 @@ def pipe_cte_with!(value)
             # Ensure we follow FIFO pattern.
             # If the parent has similar CTE alias keys, we want to favor the parent's expressions over its children's.
             if expression.is_a?(ActiveRecord::Relation) && expression.with_values?
+              expression.cte = expression.cte.dup if expression.cte
+
               # Add child's materialized keys to the parent
               @materialized_keys += expression.cte.materialized_keys
               @not_materialized_keys += expression.cte.not_materialized_keys

spec/query_methods/with_cte_spec.rb

@@ -67,5 +67,20 @@
         expect(query).to contain_exactly(user_two)
       end
     end
+
+    context "when the relation uses itself as a second CTE" do
+      it "works without a SystemStackError" do
+        user_relation = User.all
+
+        # Add first CTE to User Relation
+        group_relation = Group.all
+        user_relation_with_cte = user_relation.with('first_cte' => group_relation)
+
+        # User Relation with a CTE adds itself as another CTE
+        user_relation_with_self_cte = user_relation_with_cte.with('self_cte' => user_relation_with_cte)
+
+        expect(user_relation_with_self_cte).to contain_exactly(user_one,user_two)
+      end
+    end
   end
 end