B4nan

const book = await orm.em.findOne(Book, {
  author: {
    name: 'Jon Snow',
    address: {
      street: 'Downing Street',
    },
  },
}, ['author.address']);

console.log(book.author.name); // 'Jon Snow'

B4nan

@Entity()
export class User implements IdEntity<User> {

  @PrimaryKey()
  id!: number;

  @Property()
  name!: string;

  @OneToOne()

B4nan

import { Type, Platform, EntityProperty, ValidationError } from 'mikro-orm';

export class DateType extends Type {

  convertToDatabaseValue(value: any, platform: Platform): any {
    return value.toISOString().substr(0, 10);
  }

  convertToJSValue(value: any, platform: Platform): any {
    return new Date(value);

B4nan

{
  "name": "your-app",
  "dependencies": { ... },
  "mikro-orm": {
    "useTsNode": true,
    "configPaths": [
      "./src/mikro-orm.config.ts",
      "./dist/mikro-orm.config.js"
    ]
  }

B4nan

$ npx mikro-orm
Usage: mikro-orm <command> [options]

Commands:
  mikro-orm cache:clear             Clear metadata cache
  mikro-orm cache:generate          Generate metadata cache for production
  mikro-orm generate-entities       Generate entities based on current database
                                    schema
  mikro-orm database:import <file>  Imports the SQL file to the database
  mikro-orm schema:create           Create database schema based on current

B4nan

await em.transactional(async _em => {
  await _em.findOne(Author, id, { lockMode: LockMode.PESSIMISTIC_WRITE });
});

// START TRANSACTION
// SELECT `e0`.* FROM `author` AS `e0` WHERE `e0`.`id` = ? FOR UPDATE
// COMMIT

B4nan

const res = await fetch('api.example.com/book/123');
const book = res.json();
console.log(book.version); // prints the current version

// user does some changes and calls the PUT handler
const changes = { title: 'new title' };
await fetch('api.example.com/book/123', {
  method: 'PUT',
  body: {
    ...changes,

B4nan

const theEntityId = 1;
const expectedVersion = 184;
const entity = await orm.em.findOne(User, theEntityId);

try {
  // assert version
  await orm.em.lock(entity, LockMode.OPTIMISTIC, expectedVersion);
} catch (e) {
  console.log('Sorry, but someone else has already changed this entity. Please apply the changes again!');
}

B4nan

const theEntityId = 1;
const expectedVersion = 184;

try {
  const entity = await orm.em.findOne(User, theEntityId, { lockMode: LockMode.OPTIMISTIC, lockVersion: expectedVersion });
  // do the work
  await orm.em.flush();
} catch (e) {
  console.log('Sorry, but someone else has already changed this entity. Please apply the changes again!');
}

B4nan

export class User {
  // ...
  @Property({ version: true })
  version: number;
  // ...
}