B4nan

If:

- you add and commit with the wrong email address in git, and
- your remote has a hook set up to prevent you from pushing with the bad address

Then you need to amend the author of your commit before push can succeed:

1. fix your email address in git config:

$ git config user.name "Your Name"

B4nan

// Use Gists to store code you would like to remember later on
console.log(window); // log the "window" object to the console

B4nan

import { ObjectID } from 'mongodb';
import { Collection, Entity, IEntity, ManyToMany, ManyToOne, PrimaryKey, Property } from 'mikro-orm';
import { Author, BookTag, Publisher } from '.';

@Entity()
export class Book {

  @PrimaryKey()
  _id: ObjectID;

B4nan

const author = new Author('Jon Snow', 'snow@wall.st');
author.born = new Date();

const publisher = new Publisher('7K publisher');

const book1 = new Book('My Life on The Wall, part 1', author);
book1.publisher = publisher;
const book2 = new Book('My Life on The Wall, part 2', author);
book2.publisher = publisher;
const book3 = new Book('My Life on The Wall, part 3', author);

B4nan

// find all authors with name matching 'Jon', and populate all of their books
const authors = await orm.em.find(Author, { name: /Jon/ }, ['books']); 

for (const author of authors) {
  console.log(author.name); // Jon Snow

  for (const book of author.books) {
    console.log(book.title); // initialized
    console.log(book.author.isInitialized()); // true
    console.log(book.author.id);

B4nan

# using yarn
$ yarn add mikro-orm mongodb # for mongo
$ yarn add mikro-orm mysql2  # for mysql
$ yarn add mikro-orm pg      # for postgresql
$ yarn add mikro-orm sqlite  # for sqlite

# or npm
$ npm i -s mikro-orm mongodb # for mongo
$ npm i -s mikro-orm mysql2  # for mysql
$ npm i -s mikro-orm pg      # for postgresql

B4nan

const authorRepository = orm.em.getRepository(Author);
const jon = await authorRepository.findOne({ name: 'Jon Snow' }, ['books']);
const jon2 = await authorRepository.findOne({ email: 'snow@wall.st' });
const authors = await authorRepository.findAll(['books']);

// identity map in action
console.log(jon === authors[0]); // true
console.log(jon === jon2); // true

// as we always have one instance, books will be populated also here

B4nan

const book = orm.em.findOne(Book, '...');
console.log(book.author); // reference with ID only, instance of Author entity

// this will get the same reference as we already have in `book.author`
const author = orm.em.getReference(Author, book.author.id);
console.log(author.id); // accessing the id will not trigger any db call
console.log(author.isInitialized()); // false
console.log(author.name); // undefined
console.log(author === book.author); // true

B4nan

import { QueryOrder } from 'mikro-orm';

const booksRepository = orm.em.getRepository(Book);

// with sorting, limit and offset parameters, populating author references
const books = await booksRepository.find({ author: '...' }, ['author'], { title: QueryOrder.DESC }, 2, 1);

// or with options object
const books = await booksRepository.find({ author: '...' }, { 
  populate: ['author'],

B4nan

// find author and populate his books collection
const author = orm.em.findOne(Author, '...', ['books']);

for (const book of author.books) {
  console.log(book); // instance of Book
}

author.books.add(book);
console.log(author.books.contains(book)); // true
author.books.remove(book);