Documentation for implementing forRootAsync (#530)

[iangregsondev]

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Current behavior

Hi,

There have been some implementation details done for providing our own forRootAsync on our modules. Its mentioned here #530

I attached to implement it but I can't get it to work, it would be really nice for a small sample or some documentation.

What I have tried - and I am sure I am doing it wrong..

I have my asyncOptions

import { ModuleMetadata } from "@nestjs/common/interfaces"
import { ILoggerModuleOptions } from "./logger-module-options.interface"

export interface ILoggerModuleAsyncOptions extends Pick<ModuleMetadata, "imports"> {
  useFactory?: (...args: any[]) => Promise<ILoggerModuleOptions> | ILoggerModuleOptions
  inject?: any[]
}

It references a simple interface

import { Configuration } from "log4js"

export interface ILoggerModuleOptions {
  configuration?: string | Configuration
}

In my main app module I do the following, The configService seems to be injected BUT all the values are undefined when I call them. In fact I have a static getter on the configService to return a string and it is also undefined.

    forwardRef(() =>
      LoggerModule.forRootAsync({
        inject: [ConfigService],
        useFactory: async (configService: ConfigService) => {
          return {
            configuration: configService.connectionString
          }
        }
      })
    )

and then my logger module. I am placing the Async and non async versions, the non async version works because I am only passing a string.

export class LoggerModule {
  static forRoot(options: ILoggerModuleOptions): DynamicModule {
    return {
      exports: [SystemLoggerService],
      module: LoggerModule,
      providers: [
        SystemLoggerService
      ]
    }
  }

  static forRootAsync(options: ILoggerModuleAsyncOptions): DynamicModule {
    if (options.useFactory && options.inject) {
      const result = this.callTheFunction(options)
      console.log("result " + result)
    }

    return {
      exports: [SystemLoggerService],
      module: LoggerModule,
      providers: [SystemLoggerService]
    }
  }

  private static async callTheFunction(options: any) {
    const result = await options.useFactory(options.inject[0])
    return result
  }

I am a little lost why its not working :-)

Does anyone have a sample or has anybody actually have it working ?

I looked into the code from the typeOrm which uses this method but without documentation its a little difficult to get it working.

Thanks

[kamilmysliwiec]

I have created a corresponding issue :) Let's track this here: nestjs/docs.nestjs.com#223

[iangregsondev]

I have created a corresponding issue :) Let's track this here: nestjs/docs.nestjs.com#223

Great! Thanks, I will have a look over there and keep my eye on it.

It was one of the missing pieces that I couldn't figure out on my own :-)

[lock]

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