MNTOR-4499: subscriber id foreign key cascade for feature_flag_events

src/db/migrations/20250516139333_update_fk_feature_flag_events_cascade.js

@@ -0,0 +1,53 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * @param { import("knex").Knex } knex
+ * @returns { Promise<void> }
+ */
+export async function up(knex) {
+  await knex.schema.alterTable("feature_flag_events", (table) => {
+    // Drop the existing foreign key constraint
+    table.dropForeign(
+      ["created_by_subscriber_id"],
+      "feature_flag_events_created_by_subscriber_id_foreign",
+    );
+
+    // Add the new foreign key constraint with ON UPDATE CASCADE and ON DELETE CASCADE
+    // Explicitly naming the new constraint is good practice.
+    table
+      .foreign(
+        "created_by_subscriber_id",
+        "feature_flag_events_created_by_subscriber_id_fk_cascade",
+      )
+      .references("id")
+      .inTable("subscribers")
+      .onUpdate("CASCADE")
+      .onDelete("CASCADE");
+  });
+}
+
+/**
+ * @param { import("knex").Knex } knex
+ * @returns { Promise<void> }
+ */
+export async function down(knex) {
+  await knex.schema.alterTable("feature_flag_events", (table) => {
+    // Drop the CASCADE foreign key constraint
+    table.dropForeign(
+      ["created_by_subscriber_id"],
+      "feature_flag_events_created_by_subscriber_id_fk_cascade",
+    );
+
+    // Re-add the original foreign key constraint (defaulting to RESTRICT/NO ACTION)
+    // Ensuring the original constraint name is used.
+    table
+      .foreign(
+        "created_by_subscriber_id",
+        "feature_flag_events_created_by_subscriber_id_foreign",
+      )
+      .references("id")
+      .inTable("subscribers");
+  });
+}