Question

我是angular6的新手，并尝试在@Injectable（）装饰器中的ProvideIn属性的帮助下进行依赖项注入。

stockservice.ts

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { HelloModule } from './hello/hello.module';
@Injectable({
  providedIn: HelloModule
})
export class StockserviceService {

  constructor(private http: HttpClient) { }
  getData() {
    return this.http.get('http://localhost:4000/result');
  }
}

hellocomponent

import { Component, OnInit } from '@angular/core';
import { StockserviceService } from '../stockservice.service';
@Component({
  selector: 'app-hello',
  templateUrl: './hello.component.html',
  styleUrls: ['./hello.component.scss']
})
export class HelloComponent implements OnInit {

  constructor(private service: StockserviceService) { }

  ngOnInit() {

  }

}

hello.module.ts

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { HelloComponent } from './hello.component';
@NgModule({
  imports: [
    CommonModule
  ],
  declarations: [HelloComponent],
  exports: [HelloComponent]
})
export class HelloModule { }

在上面的代码中，我将服务注册为HelloModule的提供程序。我知道我们可以通过将'provideIn'属性值替换为'root'将服务注册为单例，但是我需要将服务注册为仅限HelloModule的提供程序。当我在home组件中导入服务时，它显示以下警告。

WARNING in Circular dependency detected:
src/app/hello/hello.component.ts -> src/app/stockservice.service.ts -> src/app/hello/hello.module.ts -> src/app/hello/hello.component.ts

WARNING in Circular dependency detected:
src/app/hello/hello.module.ts -> src/app/hello/hello.component.ts -> src/app/stockservice.service.ts -> src/app/hello/hello.module.ts

WARNING in Circular dependency detected:
src/app/stockservice.service.ts -> src/app/hello/hello.module.ts -> src/app/hello/hello.component.ts -> src/app/stockservice.service.ts

我该如何解决此问题，并借助“ provideIn”属性仅为HelloModule注册服务？

使用angular6依赖项注入时出现“检测到循环依赖”问题

0 个答案: