Angular 6.是否可以按条件注入服务? [英] Angular 6. Is it possible to inject service by condition?

问题描述

在我的有角度的应用程序(带有有角度的材质)中，我有一个过滤器面板，除了select之外，我还希望能够进行自动完成(用户输入值并将其发送到后端，从而通过$ regexp查询我们找到匹配项)在MongoDB集合中).但是要做到这一点，我需要将服务手动注入到过滤器组件中.我没有找到任何相关信息.

我需要这样的东西:

if (filters.serviceName) {
  injector.inject(serviceName);
}

injector.get(serviceName).find(searchQuery);

有可能吗?谢谢.

解决方案

是的，您可以使用演示

In my angular app (with the angular material) I have a filter panel and I want besides select to be able to make autocomplete (user input value and it sends to the back-end, whereby $regexp query we find the match in MongoDB collection). But to do it I need manually inject service into filters component. I didn't find any info on how to do it.

I need something like this:

if (filters.serviceName) {
  injector.inject(serviceName);
}

injector.get(serviceName).find(searchQuery);

Is it possible? Thanks.

解决方案

Yes you can inject service dynamically using injector.get()

Sample code :

import { Component, Injector } from '@angular/core';
import { MyService } from './my.service';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  name = 'Angular';
  myService : MyService;

  constructor(private injector : Injector){
    if(true){ // some condition
      this.myService = injector.get<MyService>(MyService);
    }

    console.log(this.myService.prop1)
  }
}

Working demo

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