NestJ无法解决循环依赖项上的服务依赖关系

Question

我的问题是在我的项目中有一个循环依赖关系。不幸的是，我不能用forwardRef解决这个问题。

以下结构：

OrderModule

• OrderService
  • 我在orderService中有以下依赖项
  • PriceService
  • CustomerService
  • SalePriceService
  • ..。

PriceModule

• PriceService
  • 我在priceService中有以下依赖项
  • OrderService
  • ProductService
  • ..。

我试过了官方文件中的所有选项。docs NestJ循环依赖关系

如果服务中有更多的依赖项，这里需要考虑什么？

非常感谢。诚挚的问候。

更新：

order.module.ts

@Module({
  imports: [
    CustomerModule,
    ProductModule,
    MongooseModule.forFeature([{ name: 'Order', schema: OrderSchema }]),
    forwardRef(() => PriceModule),
  ],
  controllers: [OrderController],
  providers: [OrderService],
  exports: [OrderService],
})
export class OrderModule {}

order.service.ts

@Injectable()
export class OrderService extends GenericCrudService<OrderDocument> {
  constructor(
    @InjectModel(Order.name) readonly order: Model<OrderDocument>,
    private readonly productService: ProductService,
    @Inject(forwardRef(() => PriceService))
    private readonly priceService: PriceService,
  ) {
    super(order);
  }
}

price.module.ts

@Module({
  imports: [
    CustomerModule,
    SalePriceModule,
    MongooseModule.forFeature([{ name: 'Price', schema: PriceSchema }]),
    forwardRef(() => OrderModule),
  ],
  controllers: [],
  providers: [PriceService],
  exports: [PriceService],
})
export class PriceModule {}

price.service.ts

@Injectable()
export class PriceService extends GenericCrudService<PriceDocument> {
  constructor(
    @InjectModel(Price.name) readonly price: Model<PriceDocument>,
    private readonly customerService: CustomerService,
    private readonly salePriceService: SalePriceService,
    @Inject(forwardRef(() => OrderService))
    private readonly orderService: OrderService,
  ) {
    super(price);
  }
}

product.module.ts

@Module({
  imports: [
    PriceModule,
    MongooseModule.forFeature([{ name: 'Product', schema: ProductSchema }]),
  ],
  controllers: [ProductController],
  providers: [ProductService],
  exports: [ProductService],
})
export class ProductModule {}

product.service.ts

@Injectable()
export class ProductService extends GenericCrudService<ProductDocument> {
  constructor(
    @InjectModel(Product.name) readonly product: Model<ProductDocument>,
  ) {
    super(product);
  }
}

我得到的错误是：

The module at index [1] of the OrderModule "imports" array is undefined.

Potential causes:
- A circular dependency between modules. Use forwardRef() to avoid it. Read more: https://docs.nestjs.com/fundamentals/circular-dependency
- The module at index [1] is of type "undefined". Check your import statements and the type of the module.

Scope [AppModule -> ProductModule -> PriceModule]
Error: Nest cannot create the OrderModule instance.
The module at index [1] of the OrderModule "imports" array is undefined.

Potential causes:
- A circular dependency between modules. Use forwardRef() to avoid it. Read more: https://docs.nestjs.com/fundamentals/circular-dependency
- The module at index [1] is of type "undefined". Check your import statements and the type of the module.

Scope [AppModule -> ProductModule -> PriceModule]

Answer 1

这里有一个明显的循环依赖关系：OrdersModule到PricesModule，然后返回，这个循环依赖是适当的forwardRef喂养的。然而，还有另一种，不太明显的循环依赖。OrdersModule到ProductsModule到PricesModule，因为下一个导入将是OrdersModule。因此，OrdersModule需要forwardRef ProductsModule，ProductsModule需要forwardRef PricesModule。看起来这些服务本身并不是循环的，所以仅仅是模块需要前向引用。始终确保检查整个导入链，特别是当Nest试图报告类似于Scope [AppModule -> ProductModule -> PriceModule]的情况时。