diff --git a/app/models/lti_parameter.rb b/app/models/lti_parameter.rb
index a6b1917b..3351a6c9 100644
--- a/app/models/lti_parameter.rb
+++ b/app/models/lti_parameter.rb
@@ -1,4 +1,8 @@
 class LtiParameter < ActiveRecord::Base
+  belongs_to :consumer, foreign_key: "consumers_id"
+  belongs_to :exercise, foreign_key: "exercises_id"
+  belongs_to :external_user, foreign_key: "external_users_id"
+
   scope :lis_outcome_service_url?, -> {
     where("lti_parameters.lti_parameters ? 'lis_outcome_service_url'")
   }
diff --git a/spec/factories/lti_parameter.rb b/spec/factories/lti_parameter.rb
index ef91f30d..9cd0f367 100644
--- a/spec/factories/lti_parameter.rb
+++ b/spec/factories/lti_parameter.rb
@@ -1,23 +1,20 @@
 FactoryGirl.define do
-  #TODO do this proper
+
+  LTI_PARAMETERS = {
+      lis_result_sourcedid: "c2db0c7c-4411-4b27-a52b-ddfc3dc32065",
+      lis_outcome_service_url: "http://172.16.54.235:3000/courses/0132156a-9afb-434d-83cc-704780104105/sections/21c6c6f4-1fb6-43b4-af3c-04fdc098879e/items/999b1fe6-d4b6-47b7-a577-ea2b4b1041ec/tool_grading",
+      launch_presentation_return_url: "http://172.16.54.235:3000/courses/0132156a-9afb-434d-83cc-704780104105/sections/21c6c6f4-1fb6-43b4-af3c-04fdc098879e/items/999b1fe6-d4b6-47b7-a577-ea2b4b1041ec/tool_return"
+  }
+
   factory :lti_parameter do
-    consumers_id 1
-    exercises_id 1
-    external_users_id 1
+    association :consumer
+    association :exercise, factory: :math
+    association :external_user
 
-    lti_parameters JSON.parse('{"lis_result_sourcedid": "c2db0c7c-4411-4b27-a52b-ddfc3dc32065",
-                              "lis_outcome_service_url": "http://172.16.54.235:3000/courses/0132156a-9afb-434d-83cc-704780104105/sections/21c6c6f4-1fb6-43b4-af3c-04fdc098879e/items/999b1fe6-d4b6-47b7-a577-ea2b4b1041ec/tool_grading",
-                              "launch_presentation_return_url": "http://172.16.54.235:3000/courses/0132156a-9afb-434d-83cc-704780104105/sections/21c6c6f4-1fb6-43b4-af3c-04fdc098879e/items/999b1fe6-d4b6-47b7-a577-ea2b4b1041ec/tool_return"}')
+    lti_parameters LTI_PARAMETERS
+
+    trait :without_outcome_service_url do
+      lti_parameters LTI_PARAMETERS.except(:lis_outcome_service_url)
+    end
   end
-
-  # factory :lti_parameter do
-  #   association :consumers_id, factory: :consumer
-  #   association :exercises_id, factory: :math
-  #   association :external_users_id, factory: :external_user
-  #
-  #
-  #   trait :lti_parameters do
-  #     JSON.parse('{"lis_result_sourcedid": "c2db0c7c-4411-4b27-a52b-ddfc3dc32065", "lis_outcome_service_url": "http://172.16.54.235:3000/courses/0132156a-9afb-434d-83cc-704780104105/sections/21c6c6f4-1fb6-43b4-af3c-04fdc098879e/items/999b1fe6-d4b6-47b7-a577-ea2b4b1041ec/tool_grading", "launch_presentation_return_url": "http://172.16.54.235:3000/courses/0132156a-9afb-434d-83cc-704780104105/sections/21c6c6f4-1fb6-43b4-af3c-04fdc098879e/items/999b1fe6-d4b6-47b7-a577-ea2b4b1041ec/tool_return"}')
-  #   end
-  # end
 end
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