How do I use tsyringe for dependency injection?

Issue type:

[x] question [ ] bug report [ ] feature request [ ] documentation issue

Database system/driver:

[ ] cordova [ ] mongodb [ ] mssql [ ] mysql / mariadb [ ] oracle [ ] postgres [ ] cockroachdb [ ] sqlite [ ] sqljs [ ] react-native [ ] expo

TypeORM version:

[x] latest [ ] @next [ ] 0.x.x (or put your version here)

Steps to reproduce or a small repository showing the problem:

[FreakyBytes]

Sure thing @fhenriques-meli !

TypeORM provides a mechanism to use an arbitrary Dependency Injection Container via useContainer. However, TypeORM expects the DI container to have a get function - TSyringe has named it resolve, hence the thin wrapper in useContainer.

Another caveat is, that TypeORM does not register anything with the DI container. (it only expects a get function) TSyringe now has the caveat of rolling with unknown injection tokens. As long as they are classes, the DI container will just create an instance. Well, this is really bad in case of TypeORM’s ConnectionManager, since this is the mechanism for TypeORM to check if a connection is available. Now, if TSyringe creates a new ConnectionManager every time TypeORM asks - no connection will ever be available (to the rest of the application). To counteract that, we manually register a Singleton Factory for it.

TL;DR: just call container.register with a singleton factory for the ConnectionManager and useContainer before creating any TypeORM connections 😃

Hope this clears things up!

[FreakyBytes]

Found this issue via Google. I’ve got TypeORM working with TSyringe with the following snippet:

import { container, instanceCachingFactory } from 'tsyringe';
import { ConnectionManager, createConnections, useContainer } from 'typeorm';

// Register TypeORM's connection manager as singleton
// TypeORM does not register anything itself with TSyringe and therefore would get a new ConnectionManager every time
container.register<ConnectionManager>(ConnectionManager, { useFactory: instanceCachingFactory(() => new ConnectionManager()) });
// configure TypeORM to use a dependency injection container
useContainer(
  // wrapper because TypeORM expects `get` function from IoC container
  { get: someClass => container.resolve(someClass as any) },
);
const connections = await createConnections(options);