update trigegr to only create if it doesn't exit

backend/src/db/migrations/20240818024923_cert-alerting.ts

@@ -13,9 +13,9 @@ export async function up(knex: Knex): Promise<void> {
       t.string("name").notNullable();
       t.string("description").notNullable();
     });
+  }
 
   await createOnUpdateTrigger(knex, TableName.PkiCollection);
-  }
 
   if (!(await knex.schema.hasTable(TableName.PkiCollectionItem))) {
     await knex.schema.createTable(TableName.PkiCollectionItem, (t) => {
@@ -28,9 +28,9 @@ export async function up(knex: Knex): Promise<void> {
       t.uuid("certId").nullable();
       t.foreign("certId").references("id").inTable(TableName.Certificate).onDelete("CASCADE");
     });
+  }
 
   await createOnUpdateTrigger(knex, TableName.PkiCollectionItem);
-  }
 
   if (!(await knex.schema.hasTable(TableName.PkiAlert))) {
     await knex.schema.createTable(TableName.PkiAlert, (t) => {
@@ -45,10 +45,10 @@ export async function up(knex: Knex): Promise<void> {
       t.string("recipientEmails").notNullable();
       t.unique(["name", "projectId"]);
     });
+  }
 
   await createOnUpdateTrigger(knex, TableName.PkiAlert);
 }
-}
 
 export async function down(knex: Knex): Promise<void> {
   await knex.schema.dropTableIfExists(TableName.PkiAlert);

backend/src/db/utils.ts

@@ -2,6 +2,9 @@ import { Knex } from "knex";
 
 import { TableName } from "./schemas";
 
+interface PgTriggerResult {
+  rows: Array<{ exists: boolean }>;
+}
 export const createJunctionTable = (knex: Knex, tableName: TableName, table1Name: TableName, table2Name: TableName) =>
   knex.schema.createTable(tableName, (table) => {
     table.uuid("id", { primaryKey: true }).defaultTo(knex.fn.uuid());
@@ -28,13 +31,26 @@ DROP FUNCTION IF EXISTS on_update_timestamp() CASCADE;
 
 // we would be using this to apply updatedAt where ever we wanta
 // remember to set `timestamps(true,true,true)` before this on schema
-export const createOnUpdateTrigger = (knex: Knex, tableName: string) =>
+export const createOnUpdateTrigger = async (knex: Knex, tableName: string) => {
-  knex.raw(`
+  const triggerExists = await knex.raw<PgTriggerResult>(`
+    SELECT EXISTS (
+      SELECT 1 
+      FROM pg_trigger 
+      WHERE tgname = '${tableName}_updatedAt'
+    );
+  `);
+
+  if (!triggerExists?.rows?.[0]?.exists) {
+    return knex.raw(`
       CREATE TRIGGER "${tableName}_updatedAt"
       BEFORE UPDATE ON ${tableName}
       FOR EACH ROW
       EXECUTE PROCEDURE on_update_timestamp();
     `);
+  }
+
+  return null;
+};
 
 export const dropOnUpdateTrigger = (knex: Knex, tableName: string) =>
   knex.raw(`DROP TRIGGER IF EXISTS "${tableName}_updatedAt" ON ${tableName}`);