When utilizing the registerAsync method in a Nest module, the framework may encounter difficulties in resolving dependencies

Question

When utilizing the registerAsync method in a Nest module, the framework may encounter difficulties in resolving dependencies

When attempting to import a Module using registerAsync and configuring it with a provider from my module, I encounter an error stating that the provider cannot be found. Can anyone help identify what I am missing?

Here is my code snippet:

import { CacheModule, Module } from '@nestjs/common';

@Module({
  imports:     [
    CacheModule.registerAsync({
      useFactory: async (options) => ({
        ttl: options.ttl,
      }),
      inject: ['MY_OPTIONS'],
    }),
  ],
  providers:   [
    {
      provide:  'MY_OPTIONS',
      useValue: {
        ttl: 60,
      },
    },
  ],
})
export class AppModule {
}

Error message received:

Error: Nest can't resolve dependencies of the CACHE_MODULE_OPTIONS (?). Please make sure that the argument MY_OPTIONS at index [0] is available in the CacheModule context.

The provided example simplifies my actual code, but the core issue remains: I have a provider within the AppModule that needs to be accessed in the CacheModule.registerAsync() function.

If anyone would like to assist in troubleshooting this problem, I have created a simple repository here: https://github.com/MickL/nestjs-inject-existing-provider

typescript nestjs

Answer 1

Answer №1

This may seem unusual, but even with the same @Module, it's necessary to explicitly inform the dependency manager about imports and exports as shown below:

import { CacheModule, Module } from '@nestjs/common';

@Module({
  imports:     [
    CacheModule.registerAsync({
      imports: [AppModule], // <-- ADDED
      useFactory: async (options) => {
        console.log('MY_OPTIONS', options) // <-- LOGS FINE upon NestFactory.create(AppModule)
        return {
          ttl: options.ttl,
        }
      },
      inject: ['MY_OPTIONS'],
    }),
  ],
  providers:   [
    {
      provide:  'MY_OPTIONS',
      useValue: {
        ttl: 60,
      },
    },
  ],
  exports: ['MY_OPTIONS'] // <-- ADDED
})
export class AppModule {
}

REVISITED

After examining your repository, particularly the file src/my-lib.module.ts, the following appears to be functioning (though not completely resolving the underlying issue):

export class MyLibModule {
  // changed to async version by returning Promise
  static register(options: ModuleOptions): Promise<DynamicModule> {
    // retains reference to newly created module
    const OptionsModule = MyLibOptionsModule.register(options)
    // prints 'true', yet importing MyLibOptionsModule still doesn't work
    console.log('who-am-i', OptionsModule.module === MyLibOptionsModule)
    return Promise.resolve({
      module: MyLibModule,
      imports: [
        // OptionsModule, // seems unnecessary
        HttpModule.registerAsync({
          useFactory: ((options: ModuleOptions) => {
            console.log("Works:", options);
            return {
              url: options.externalApiUrl,
              timeout: options.timeout
            };
          }),
          // successfully imports using the newly created reference
          imports: [OptionsModule],
          inject: [MODULE_OPTIONS]
        })
      ]
    });
  }
}

Answer 2

This may seem unusual, but even with the same @Module, it's necessary to explicitly inform the dependency manager about imports and exports as shown below:

import { CacheModule, Module } from '@nestjs/common';

@Module({
  imports:     [
    CacheModule.registerAsync({
      imports: [AppModule], // <-- ADDED
      useFactory: async (options) => {
        console.log('MY_OPTIONS', options) // <-- LOGS FINE upon NestFactory.create(AppModule)
        return {
          ttl: options.ttl,
        }
      },
      inject: ['MY_OPTIONS'],
    }),
  ],
  providers:   [
    {
      provide:  'MY_OPTIONS',
      useValue: {
        ttl: 60,
      },
    },
  ],
  exports: ['MY_OPTIONS'] // <-- ADDED
})
export class AppModule {
}

REVISITED

After examining your repository, particularly the file src/my-lib.module.ts, the following appears to be functioning (though not completely resolving the underlying issue):

export class MyLibModule {
  // changed to async version by returning Promise
  static register(options: ModuleOptions): Promise<DynamicModule> {
    // retains reference to newly created module
    const OptionsModule = MyLibOptionsModule.register(options)
    // prints 'true', yet importing MyLibOptionsModule still doesn't work
    console.log('who-am-i', OptionsModule.module === MyLibOptionsModule)
    return Promise.resolve({
      module: MyLibModule,
      imports: [
        // OptionsModule, // seems unnecessary
        HttpModule.registerAsync({
          useFactory: ((options: ModuleOptions) => {
            console.log("Works:", options);
            return {
              url: options.externalApiUrl,
              timeout: options.timeout
            };
          }),
          // successfully imports using the newly created reference
          imports: [OptionsModule],
          inject: [MODULE_OPTIONS]
        })
      ]
    });
  }
}

Answer 3

Answer №2

The issue arises from the discrepancy in level between "CacheModule.registerAsync" and "AppModule", resulting in a provider defined in "AppModule" not being accessible to "CacheModule.registerAsync".

If we were to transfer the "MY_OPTIONS" to a separate module called "CacheConfigModule", the code could be structured like this:

CacheConfigModule.ts

import { Module } from '@nestjs/common';

@Module({
  providers: [
    {
      provide: 'MY_OPTIONS',
      useValue: {
        ttl: 60
      }
    }
  ],
  exports: ['MY_OPTIONS']
})
export class CacheConfigModule {}

AppModule.ts

import { CacheModule, Module } from '@nestjs/common';
import { CacheConfigModule } from './CacheConfigModule';

@Module({
  imports: [
    CacheConfigModule,
    CacheModule.registerAsync({
      imports: [CacheConfigModule],
      useFactory: async (options) => ({
        ttl: options.ttl
      }),
      inject: ['MY_OPTIONS']
    })
  ]
})
export class AppModule {}

Answer 4

The issue arises from the discrepancy in level between "CacheModule.registerAsync" and "AppModule", resulting in a provider defined in "AppModule" not being accessible to "CacheModule.registerAsync".

If we were to transfer the "MY_OPTIONS" to a separate module called "CacheConfigModule", the code could be structured like this:

CacheConfigModule.ts

import { Module } from '@nestjs/common';

@Module({
  providers: [
    {
      provide: 'MY_OPTIONS',
      useValue: {
        ttl: 60
      }
    }
  ],
  exports: ['MY_OPTIONS']
})
export class CacheConfigModule {}

AppModule.ts

import { CacheModule, Module } from '@nestjs/common';
import { CacheConfigModule } from './CacheConfigModule';

@Module({
  imports: [
    CacheConfigModule,
    CacheModule.registerAsync({
      imports: [CacheConfigModule],
      useFactory: async (options) => ({
        ttl: options.ttl
      }),
      inject: ['MY_OPTIONS']
    })
  ]
})
export class AppModule {}

When utilizing the registerAsync method in a Nest module, the framework may encounter difficulties in resolving dependencies

Answer №1

REVISITED

Answer №2

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