Nest.js Model Dependency Injection with Mongoose with no constructor-CodePudding

I need to integrate a CRM API with my service in Nest.js. Unfortunately, they require I implement their interface to use a custom persistence layer, in my case, Mongo. Since I'll need to instantiate the resulting class, I can't inject the model as I normally would so I tried using this on the class member variable instead. However, this results in an error that the member variable is undefined.

This is my mongoose model:

export type ZohoTokenDocument = ZohoToken & Document;

@Schema({ timestamps: true })
export class ZohoToken {
  @Prop()
  name: string;

  @Prop({ type: String, length: 255, unique: true })
  user_mail: string;

  @Prop({ type: String, length: 255, unique: true })
  client_id: string;

  @Prop({ type: String, length: 255 })
  refresh_token: string;

  @Prop({ type: String, length: 255 })
  access_token: string;

  @Prop({ type: String, length: 255 })
  grant_token: string;

  @Prop({ type: String, length: 20 })
  expiry_time: string;
}

export const ZohoTokenSchema = SchemaFactory.createForClass(ZohoToken);

This is the custom class I'm creating as required by the 3rd party API:

export class ZohoStore implements TokenStore {
  @InjectModel(ZohoToken.name)
  private readonly tokenModel: Model<ZohoTokenDocument>;

  async getToken(user, token): Promise<any> {
    const result = await this.tokenModel.findOne({ grant_token: token });
    return result;
  }
...

And in my service, I'm just instantiating this class as new ZohoStore(), which works fine until the getToken() method is called later.

The resulting error is: "nullTypeError: Cannot read property 'findOne' of undefined",, which to me means the tokenModel is not being instantiated. Any idea how I can get my model injected into this class without putting it in the constructor, otherwise I can't instantiate it with a zero-arg constructor from my service?

CodePudding user response：

If you're trying to use Nest DI system, then you just can't call new ZohoStore() by yourself because Nest has no chance to instantiate ZohoStore's dependencies.

You'll need to register it as a provider in some NestJS module and then retrive the instance created by NestJS if you want to.