Refactor LTI parameters and add study group

* This change also requires that submissions in our test need to have a valid study group.

db/migrate/20230819084916_add_study_group_to_lti_parameters.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddStudyGroupToLtiParameters < ActiveRecord::Migration[7.0]
+  def change
+    add_reference :lti_parameters, :study_group, index: true, null: true, foreign_key: true
+  end
+end

db/migrate/20230819084917_unify_lti_parameters.rb

@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+class UnifyLtiParameters < ActiveRecord::Migration[7.0]
+  def change
+    reversible do |dir|
+      dir.up do
+        # We cannot add a foreign key to a table that has rows that violate the constraint.
+        LtiParameter.where(external_users_id: nil)
+          .or(LtiParameter.where.not(external_users_id: ExternalUser.all.select(:id)))
+          .or(LtiParameter.where(exercises_id: nil))
+          .or(LtiParameter.where.not(exercises_id: Exercise.all.select(:id)))
+          .delete_all
+
+        # For each user/exercise pair, keep the most recent LtiParameter.
+        LtiParameter.all.group(:external_users_id, :exercises_id).having('count(*) > 1').count.each do |ids, count|
+          LtiParameter.where(external_users_id: ids.first, exercises_id: ids.second).order(updated_at: :asc).limit(count - 1).delete_all
+        end
+        change_column :lti_parameters, :id, :bigint
+      end
+
+      dir.down do
+        change_column :lti_parameters, :id, :integer
+      end
+    end
+
+    remove_column :lti_parameters, :consumers_id, :bigint
+
+    rename_column :lti_parameters, :external_users_id, :external_user_id
+    change_column_null :lti_parameters, :external_user_id, false
+    add_foreign_key :lti_parameters, :external_users
+
+    rename_column :lti_parameters, :exercises_id, :exercise_id
+    change_column_null :lti_parameters, :exercise_id, false
+    add_foreign_key :lti_parameters, :exercises
+
+    add_index :lti_parameters, %i[external_user_id study_group_id exercise_id], unique: true, name: 'index_lti_params_on_external_user_and_study_group_and_exercise'
+  end
+
+  class LtiParameter < ActiveRecord::Base; end
+
+  class ExternalUser < ActiveRecord::Base; end
+
+  class Exercise < ActiveRecord::Base; end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.0].define(version: 2023_07_27_080619) do
+ActiveRecord::Schema[7.0].define(version: 2023_08_19_084917) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_trgm"
   enable_extension "pgcrypto"
@@ -341,14 +341,16 @@ ActiveRecord::Schema[7.0].define(version: 2023_07_27_080619) do
     t.string "severity"
   end
 
-  create_table "lti_parameters", id: :serial, force: :cascade do |t|
-    t.integer "external_users_id"
-    t.integer "consumers_id"
-    t.integer "exercises_id"
+  create_table "lti_parameters", force: :cascade do |t|
+    t.integer "external_user_id", null: false
+    t.integer "exercise_id", null: false
     t.jsonb "lti_parameters", default: {}, null: false
     t.datetime "created_at"
     t.datetime "updated_at"
-    t.index ["external_users_id"], name: "index_lti_parameters_on_external_users_id"
+    t.bigint "study_group_id"
+    t.index ["external_user_id", "study_group_id", "exercise_id"], name: "index_lti_params_on_external_user_and_study_group_and_exercise", unique: true
+    t.index ["external_user_id"], name: "index_lti_parameters_on_external_user_id"
+    t.index ["study_group_id"], name: "index_lti_parameters_on_study_group_id"
   end
 
   create_table "programming_group_memberships", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
@@ -599,6 +601,9 @@ ActiveRecord::Schema[7.0].define(version: 2023_07_27_080619) do
   add_foreign_key "exercise_tips", "exercise_tips", column: "parent_exercise_tip_id"
   add_foreign_key "exercise_tips", "exercises"
   add_foreign_key "exercise_tips", "tips"
+  add_foreign_key "lti_parameters", "exercises"
+  add_foreign_key "lti_parameters", "external_users"
+  add_foreign_key "lti_parameters", "study_groups"
   add_foreign_key "programming_group_memberships", "programming_groups"
   add_foreign_key "programming_groups", "exercises"
   add_foreign_key "remote_evaluation_mappings", "study_groups"

db/scripts/migrate_exercise.sql

@@ -40,7 +40,7 @@ BEGIN
 
     DELETE FROM anomaly_notifications WHERE exercise_id = duplicated_exercise;
     DELETE FROM exercise_tags WHERE exercise_id = duplicated_exercise;
-    DELETE FROM lti_parameters WHERE exercises_id = duplicated_exercise;
+    DELETE FROM lti_parameters WHERE exercise_id = duplicated_exercise;
     DELETE FROM remote_evaluation_mappings WHERE exercise_id = duplicated_exercise;
 
     -- Preventing duplicated entries in exercise_collection_items