Typeorm Transactional

It's a fork of typeorm-transactional-cls-hooked for new versions of TypeORM.

A Transactional Method Decorator for typeorm that uses ALS or cls-hooked to handle and propagate transactions between different repositories and service methods.

See Changelog

• Typeorm Transactional
  • It's a fork of typeorm-transactional-cls-hooked for new versions of TypeORM.
  • Installation
  • Initialization
  • Usage
  • Using Transactional Decorator
  • Data Sources
  • Transaction Propagation
  • Isolation Levels
  • Hooks
  • Unit Test Mocking
  • API
    • Library Options
    • Transaction Options
    • Storage Driver
    • initializeTransactionalContext(options): void
    • addTransactionalDataSource(input): DataSource
    • runInTransaction(fn: Callback, options?: Options): Promise<...>
    • wrapInTransaction(fn: Callback, options?: Options): WrappedFunction
    • runOnTransactionCommit(cb: Callback): void
    • runOnTransactionRollback(cb: Callback): void
    • runOnTransactionComplete(cb: Callback): void

Installation

## npm
npm install --save typeorm-transactional

## Needed dependencies
npm install --save typeorm reflect-metadata

Or

yarn add typeorm-transactional

## Needed dependencies
yarn add typeorm reflect-metadata

Note: You will need to import reflect-metadata somewhere in the global place of your app - https://github.com/typeorm/typeorm#installation

Initialization

In order to use it, you will first need to initialize the transactional context before your application is started

import { initializeTransactionalContext } from 'typeorm-transactional';

initializeTransactionalContext()
...
app = express()
...

IMPORTANT NOTE

Calling initializeTransactionalContext must happen BEFORE any application context is initialized!

Usage

New versions of TypeORM use DataSource instead of Connection, so most of the API has been changed and the old API has become deprecated.

To be able to use TypeORM entities in transactions, you must first add a DataSource using the addTransactionalDataSource function:

import { DataSource } from 'typeorm';
import { initializeTransactionalContext, addTransactionalDataSource, StorageDriver } from 'typeorm-transactional';
...
const dataSource = new DataSource({
	type: 'postgres',
    host: 'localhost',
    port: 5435,
    username: 'postgres',
    password: 'postgres'
});
...

initializeTransactionalContext({ storageDriver: StorageDriver.ASYNC_LOCAL_STORAGE });
addTransactionalDataSource(dataSource);

...

Example for Nest.js:

// main.ts

import { NestFactory } from '@nestjs/core';
import { initializeTransactionalContext } from 'typeorm-transactional';

import { AppModule } from './app';

const bootstrap = async () => {
  initializeTransactionalContext();

  const app = await NestFactory.create(AppModule, {
    abortOnError: true,
  });

  await app.listen(3000);
};

bootstrap();

// app.module.ts

import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';
import { DataSource } from 'typeorm';
import { addTransactionalDataSource } from 'typeorm-transactional';

@Module({
	imports: [
	   TypeOrmModule.forRootAsync({
	     useFactory() {
	       return {
	         type: 'postgres',
	         host: 'localhost',
	         port: 5435,
	         username: 'postgres',
	         password: 'postgres',
	         synchronize: true,
	         logging: false,
	       };
	     },
	     async dataSourceFactory(options) {
	       if (!options) {
	         throw new Error('Invalid options passed');
	       }

	       return addTransactionalDataSource(new DataSource(options));
	     },
	   }),

	   ...
	 ],
	 providers: [...],
	 exports: [...],
})
class AppModule {}

Unlike typeorm-transactional-cls-hooked, you do not need to use BaseRepositoryor otherwise define repositories.

You can also use this library with custom TypeORM repositories. You can read more about them here and here.

NOTE: You can add multiple DataSource if you need it

Using Transactional Decorator

• Every service method that needs to be transactional, need to use the @Transactional() decorator
• The decorator can take a connectionName as argument (by default it is default) to specify the data source to be user
• The decorator can take an optional propagation as argument to define the propagation behaviour
• The decorator can take an optional isolationLevel as argument to define the isolation level (by default it will use your database driver's default isolation level)

export class PostService {
  constructor(readonly repository: PostRepository)

  @Transactional() // Will open a transaction if one doesn't already exist
  async createPost(id, message): Promise<Post> {
    const post = this.repository.create({ id, message })
    return this.repository.save(post)
  }
}

You can also use DataSource/EntityManager objects together with repositories in transactions:

export class PostService {
  constructor(readonly repository: PostRepository, readonly dataSource: DataSource)

  @Transactional() // Will open a transaction if one doesn't already exist
  async createAndGetPost(id, message): Promise<Post> {
    const post = this.repository.create({ id, message })

    await this.repository.save(post)

    return dataSource.createQueryBuilder(Post, 'p').where('id = :id', id).getOne();
  }
}

Data Sources

In new versions of TypeORM the name property in Connection / DataSource is deprecated, so to work conveniently with multiple DataSource the function addTransactionalDataSource allows you to specify custom the name:

addTransactionalDataSource({
	name: 'second-data-source',
	dataSource: new DataSource(...)
});

If you don't specify a name, it defaults to default.

Now, you can use this name in API by passing the connectionName property as options to explicitly define which Data Source you want to use:

  @Transactional({ connectionName: 'second-data-source' })
  async fn() { ... }

OR

runInTransaction(() => {
  // ...
}, { connectionName: 'second-data-source' })

Transaction Propagation

The following propagation options can be specified:

• MANDATORY - Support a current transaction, throw an exception if none exists.
• NESTED - Execute within a nested transaction if a current transaction exists, behave like REQUIRED else.
• NEVER - Execute non-transactionally, throw an exception if a transaction exists.
• NOT_SUPPORTED - Execute non-transactionally, suspend the current transaction if one exists.
• REQUIRED (default behaviour) - Support a current transaction, create a new one if none exists.
• REQUIRES_NEW - Create a new transaction, and suspend the current transaction if one exists.
• SUPPORTS - Support a current transaction, execute non-transactionally if none exists.

Isolation Levels

The following isolation level options can be specified:

• READ_UNCOMMITTED - A constant indicating that dirty reads, non-repeatable reads and phantom reads can occur.
• READ_COMMITTED - A constant indicating that dirty reads are prevented; non-repeatable reads and phantom reads can occur.
• REPEATABLE_READ - A constant indicating that dirty reads and non-repeatable reads are prevented; phantom reads can occur.
• SERIALIZABLE = A constant indicating that dirty reads, non-repeatable reads and phantom reads are prevented.

NOTE: If a transaction already exist and a method is decorated with @Transactional and propagation does not equal to REQUIRES_NEW, then the declared isolationLevel value will not be taken into account.

Hooks

Because you hand over control of the transaction creation to this library, there is no way for you to know whether or not the current transaction was successfully persisted to the database.

To circumvent that, we expose three helper methods that allow you to hook into the transaction lifecycle and take appropriate action after a commit/rollback.

• runOnTransactionCommit(cb) takes a callback to be executed after the current transaction was successfully committed
• runOnTransactionRollback(cb) takes a callback to be executed after the current transaction rolls back. The callback gets the error that initiated the rollback as a parameter.
• runOnTransactionComplete(cb) takes a callback to be executed at the completion of the current transactional context. If there was an error, it gets passed as an argument.

export class PostService {
    constructor(readonly repository: PostRepository, readonly events: EventService) {}

    @Transactional()
    async createPost(id, message): Promise<Post> {
        const post = this.repository.create({ id, message });
        const result = await this.repository.save(post);

        runOnTransactionCommit(() => this.events.emit('post created'));

        return result;
    }
}

Unit Test Mocking

@Transactional can be mocked to prevent running any of the transactional code in unit tests.

This can be accomplished in Jest with:

jest.mock('typeorm-transactional', () => ({
  Transactional: () => () => ({}),
}));

Repositories, services, etc. can be mocked as usual.

API

Library Options

{
  storageDriver?: StorageDriver,
  maxHookHandlers?: number
}

• storageDriver - Determines which underlying mechanism (like Async Local Storage or cls-hooked) the library should use for handling and propagating transactions. By default, it's StorageDriver.CLS_HOOKED.
• maxHookHandlers - Controls how many hooks (commit, rollback, complete) can be used simultaneously. If you exceed the number of hooks of same type, you get a warning. This is a useful to find possible memory leaks. You can set this options to 0 or Infinity to indicate an unlimited number of listeners. By default, it's 10.

Transaction Options

{
  connectionName?: string;
  isolationLevel?: IsolationLevel;
  propagation?: Propagation;
}

• connectionName- DataSource name to use for this transactional context (the data sources)
• isolationLevel- isolation level for transactional context (isolation levels )
• propagation- propagation behaviors for nest transactional contexts (propagation behaviors)

Storage Driver

Option that determines which underlying mechanism the library should use for handling and propagating transactions.

The possible variants:

• AUTO - Automatically selects the appropriate storage mechanism based on the Node.js version, using AsyncLocalStorage for Node.js versions 16 and above, and defaulting to cls-hooked for earlier versions.
• CLS_HOOKED - Utilizes the cls-hooked package to provide context storage, supporting both legacy Node.js versions with AsyncWrap for versions below 8.2.1, and using async_hooks for later versions.
• ASYNC_LOCAL_STORAGE - Uses the built-in AsyncLocalStorage feature, available from Node.js version 16 onwards,

⚠️ WARNING: Currently, we use CLS_HOOKED by default for backward compatibility. However, in the next major release, this default will be switched to AUTO.

import { StorageDriver } from 'typeorm-transactional'

initializeTransactionalContext({ storageDriver: StorageDriver.AUTO });

initializeTransactionalContext(options): void

Initialize transactional context.

initializeTransactionalContext(options?: TypeormTransactionalOptions);

Optionally, you can set some options.

addTransactionalDataSource(input): DataSource

Add TypeORM DataSource to transactional context.

addTransactionalDataSource(new DataSource(...));

addTransactionalDataSource({ name: 'default', dataSource: new DataSource(...), patch: true });

runInTransaction(fn: Callback, options?: Options): Promise<...>

Run code in transactional context.

...

runInTransaction(() => {
	...

	const user = this.usersRepo.update({ id: 1000 }, { state: action });

	...
}, { propagation: Propagation.REQUIRES_NEW });

...

wrapInTransaction(fn: Callback, options?: Options): WrappedFunction

Wrap function in transactional context

...

const updateUser = wrapInTransaction(() => {
	...

	const user = this.usersRepo.update({ id: 1000 }, { state: action });

	...
}, { propagation: Propagation.NEVER });

...

await updateUser();

...

runOnTransactionCommit(cb: Callback): void

Takes a callback to be executed after the current transaction was successfully committed

  @Transactional()
  async createPost(id, message): Promise<Post> {
      const post = this.repository.create({ id, message });
      const result = await this.repository.save(post);

      runOnTransactionCommit(() => this.events.emit('post created'));

      return result;
  }

runOnTransactionRollback(cb: Callback): void

Takes a callback to be executed after the current transaction rolls back. The callback gets the error that initiated the rollback as a parameter.

  @Transactional()
  async createPost(id, message): Promise<Post> {
      const post = this.repository.create({ id, message });
      const result = await this.repository.save(post);

      runOnTransactionRollback((e) => this.events.emit(e));

      return result;
  }

runOnTransactionComplete(cb: Callback): void

Takes a callback to be executed at the completion of the current transactional context. If there was an error, it gets passed as an argument.

  @Transactional()
  async createPost(id, message): Promise<Post> {
      const post = this.repository.create({ id, message });
      const result = await this.repository.save(post);

      runOnTransactionComplete((e) => this.events.emit(e ? e : 'post created'));

      return result;
  }