node.js - How to integrate Mongoose and GridFS to NestJS?

Question

Whats is the correct way to work with Mongoose and GridFS?

I'm trying to add Mongodb Gridfs to NestJS Example 14 (https://github.com/nestjs/nest/tree/master/sample/14-mongoose-base)

But when I use the tag @InjectConnection:

  // files.service.ts
  private readonly fileModel: MongoGridFS;
  constructor(@InjectConnection() private readonly connection: Connection) {
    this.fileModel = new MongoGridFS(this.connection.db, 'fs');
  }
  async readStream(id: string): Promise<GridFSBucketReadStream> {
    return await this.fileModel.readFileStream(id);
  }

The following error occurs:

[Nest] 24282   - 04/20/2020, 4:10:23 PM   [ExceptionHandler] Nest can't resolve dependencies of the FilesService (?). Please make sure that the argument DatabaseConnection at index [0] is available in the FilesModule context.

Potential solutions:
- If DatabaseConnection is a provider, is it part of the current FilesModule?
- If DatabaseConnection is exported from a separate @Module, is that module imported within FilesModule?
  @Module({
    imports: [ /* the Module containing DatabaseConnection */ ]
  })

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

Answer 1

由于MongooseModule不是@Global()，您需要在需要数据库连接的任何地方导入模块。在您的示例中，您只有MulterModule正在导入的内容，因此当您尝试执行时@InjectConnection()，Nest 无法找到来源MongooseModule的Connection来源，从而引发错误。导入MongooseModule以解决此问题。