Expose resolveContainer and createContainer to public?

[captainjapeng]

I'm currently using this library with apollo graphql, I would like to create a DataLoader on each request. But in order to do that, DataLoader depends on a DBConnection.

It would be nice if we can reuse existing instantiated classes by using resolveContainer.

[DreamTexX]

I guess that would be possible, probably by exposing an Application class with some Methods. I will take a look at this tomorrow!

Is your DataLoader a Module/Service? In that case you could simply inject the connection into it.

[captainjapeng]

I initially implemented it as a service but then dataloaders should be created on a per request basis so I have to instantiate it multiple times.

[DreamTexX]

Would something like this work for you?

// Dummy class for connection infos
class Connection {}

// Your real DataLoader implementation which utilizes a connection
class DataLoader() {
  constructor(private final connection: Connection) {}
}

// A wrapper around your DataLoader, which creates a fresh instance on demand
class DataLoaderFactory {
  @Inject(Connection)
  connection!: Connection;
  
  public create() {
    return new DataLoader(this.connection);
  }
}

// Dummy consumer
class Consumer {
  @Inject(DataLoaderFactory)
  dataLoaderFactory!: DataLoaderFactory;
  
  @PostModuleInit()
  public postModuleInit() {
    let dataLoader = dataLoaderFactory.create();
    // Work with fresh instance of DataLoader
  }
}

// Inject only Connection and Factory as providers
@Module({
  providers: [Connection, DataLoaderFactory],
  consumers: [Consumer],
})
class Module {}

new Application(Module).boot();

Please notice, there will come some new features in the next version featuring an application class. Also @OnModuleInit will not exist anymore and gets replaced by Hooks (@PostModuleInit).

[captainjapeng]

This can work, in my case, I would call dataLoaderFactory.create() inside the function that handles graphql queries. We could also improve it as well if we'll pass a Context variable to create(ctx) so we can cache the dataloader on a per request/context 😄

[DreamTexX]

I think doing it this way is much cleaner. It would be a very "hacky" way implementing any method to resolve a provider outside of the modules.