Martin Adámek B4nan

Long time php/nette/doctrine developer, now shifted to javascript world (node/typescript/angular). Building MikroORM in my free time.

B4nan / implicit-transaction-simple.ts

Last active June 16, 2019 17:23

Simple example of implicit transactions in MikroORM

	const user = new User();
	user.name = 'George';
	await orm.em.persistAndFlush(user);

B4nan / implicit-transaction-complex.ts

Created June 16, 2019 16:56

More complex example of implicit transaction in MikroORM

	const author = await orm.em.findOne(Author, id, ['books.tags', 'books.publisher']);
	author.books[0].title = 'New book name';
	author.books[0].tags[0].name = 'old';
	author.books[0].tags.add(new BookTag('sale'));
	author.books[0].publisher.name = 'New publisher name';
	await orm.em.flush();

B4nan / implicit-transaction-complex.sql

Created June 16, 2019 16:57

Actual SQL queries ran when flushing in implicit-transaction-complex.ts example in MikroORM

	START TRANSACTION;
	INSERT INTO `book_tag` (`name`) VALUES (?);
	UPDATE `book` SET `title` = ? WHERE `id` = ?;
	DELETE FROM `book_to_book_tag` WHERE `book_id` = ?;
	INSERT INTO `book_to_book_tag` (`book_id`, `book_tag_id`) VALUES (?, ?);
	INSERT INTO `book_to_book_tag` (`book_id`, `book_tag_id`) VALUES (?, ?);
	UPDATE `publisher` SET `name` = ? WHERE `id` = ?;
	UPDATE `book_tag` SET `name` = ? WHERE `id` = ?;
	COMMIT;

B4nan / explicit-transaction-manual.ts

Created June 16, 2019 17:00

Explicit transaction handling in MikroORM

	await orm.em.beginTransaction();

	try {
	//... do some work
	const user = new User(...);
	user.name = 'George';
	await orm.em.persistAndFlush(user);
	await orm.em.commit();
	} catch (e) {
	await orm.em.rollback();

B4nan / explicit-transaction-helper.ts

Last active June 17, 2019 18:51

Explicit transactions via EM.transactional() in MikroORM

	await orm.em.transactional(async _em => {
	//... do some work
	const user = new User(...);
	user.name = 'George';
	_em.persistLater(user);
	});

B4nan / 01-version-prop-int.ts

Last active June 17, 2019 19:24

Defining version properties for optimistic locking in MikroORM

B4nan / find-one-optimistic-lock.ts

Last active June 17, 2019 21:56

Using optimistic lock via em.findOne() in MikroORM

	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 / em-lock.ts

Created June 17, 2019 19:43

Using optimistic lock via em.lock() in MikroORM

	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 / 01-optimistic-locking-frontend.ts

Created June 17, 2019 21:12

	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 / 01-pessimistic-lock-write.ts

Last active June 17, 2019 21:27

Perssimistic locking in MikroORM

	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