switch to sequelize orm

package.json

@@ -56,6 +56,7 @@
     "@loopback/rest-explorer": "^5.0.8",
     "@loopback/service-proxy": "^5.0.8",
     "loopback-connector-postgresql": "^5.5.2",
+    "loopback4-sequelize": "file:loopback4-sequelize-2.1.0-new.tgz",
     "tslib": "^2.0.0"
   },
   "devDependencies": {

src/controllers/user.controller.ts

@@ -3,7 +3,6 @@ import {
   CountSchema,
   Filter,
   FilterExcludingWhere,
-  IsolationLevel,
   repository,
   Where,
 } from '@loopback/repository';
@@ -18,6 +17,7 @@ import {
   requestBody,
   response,
 } from '@loopback/rest';
+import {Transaction} from 'loopback4-sequelize';
 import {User} from '../models';
 import {UserRepository} from '../repositories';
 
@@ -36,7 +36,7 @@ export class UserController {
     // Begin a new transaction.
     // It's also possible to call `userRepo.dataSource.beginTransaction` instead.
     const tx = await this.userRepository.beginTransaction({
-      isolationLevel: IsolationLevel.SERIALIZABLE,
+      isolationLevel: Transaction.ISOLATION_LEVELS.SERIALIZABLE,
     });
 
     try {

src/datasources/db.datasource.ts

@@ -1,5 +1,5 @@
 import {inject, lifeCycleObserver, LifeCycleObserver} from '@loopback/core';
-import {juggler} from '@loopback/repository';
+import {SequelizeDataSource} from 'loopback4-sequelize';
 
 const config = {
   name: 'db',
@@ -17,7 +17,7 @@ const config = {
 // Learn more at https://loopback.io/doc/en/lb4/Life-cycle.html
 @lifeCycleObserver('datasource')
 export class DbDataSource
-  extends juggler.DataSource
+  extends SequelizeDataSource
   implements LifeCycleObserver
 {
   static dataSourceName = 'db';

src/repositories/user.repository.ts

@@ -1,9 +1,9 @@
 import {inject} from '@loopback/core';
-import {DefaultTransactionalRepository} from '@loopback/repository';
+import {SequelizeCrudRepository} from 'loopback4-sequelize';
 import {DbDataSource} from '../datasources';
 import {User, UserRelations} from '../models';
 
-export class UserRepository extends DefaultTransactionalRepository<
+export class UserRepository extends SequelizeCrudRepository<
   User,
   typeof User.prototype.id,
   UserRelations