NestJS + TypeORM: Use two or more databases?

Question

I\'m trying since 2 days to solve this, perhaps I\'m simply missing the point here.

My goal was to write a NestJS app (with TypeORM included) which serves a RestAPI

Answer 1

You need to explicitly pass the connection name at the same level inside TypeOrmModule.forRoot({ name: 'db1Connection' }) incase you are using multiple database connections.

TypeOrmModule.forRootAsync({
  name: DB1_CONNECTION,
  imports: [ConfigModule],
  useClass: TypeormDb1ConfigService,
}),

TypeOrmModule.forRootAsync({
  name: DB2_CONNECTION,
  imports: [ConfigModule],
  useClass: TypeormDb2ConfigService,
})

Answer 2

For clarity and for other developers to come to this post:

From NestJS documentation:

If you don't set any name for a connection, its name is set to default. Please note that you shouldn't have multiple connections without a name, or with the same name, otherwise they simply get overridden.

One of your connections must have one of the following:

1. "name":"default"
2. Without any name.

I would recommend to declare all your connections in ormconfig.json and not declare it in code.

An example to import the connections from ormconfig.json:

@Module({
    imports: [TypeOrmModule.forFeature([Entity1, Entity2]), //This will use default connection
    TypeOrmModule.forRoot({name: 'con1'}), // This will register globaly con1
    TypeOrmModule.forRoot({name: 'con2'}), // This will register globaly con2
    controllers: [...],
    providers: [...],
    exports: [...]
})

in your module (not have to be the root module, only the modules you will need the connections).

Answer 3

I just tried setting up TypeORM with multiple databases and a ormconfig.json and it did not work for me at all. It seemed to always use the default connection and when no default (= without explicit name) connection was found it threw the corresponding error.

It did work though when I defined the connections in the app.module.ts instead (I removed ormconfig.json):

imports: [
  ...,
  TypeOrmModule.forRoot({
    name: 'Project1',
    type: 'mysql',
    host: 'localhost',
    port: 3306,
    username: '<username>',
    password: '<pwd>',
    database: '<database>',
    synchronize: false,
    entities: ['project1/*.entity.ts'],
    subscribers: ['project1/*.subscriber.ts'],
    migrations: ['project1/migrations/*.ts'],
    cli: { migrationsDir: 'project1/migrations' },
  }),
  TypeOrmModule.forRoot({
    name: 'project2',
    type: 'mysql',
    host: 'localhost',
    port: 3306,
    username: '<another-username>',
    password: '<another-pwd>',
    database: '<another-database>',
    synchronize: false,
    entities: ['project2/*.entity.ts'],
    subscribers: ['project2/*.subscriber.ts'],
    migrations: ['project2/migrations/*.ts'],
    cli: { migrationsDir: 'project2/migrations' },
  })
]