将数据从子组件传递到父组件 [英] Passing Data From Child Component Into Parent Component

问题描述

我的角度有问题，这里有两个组件:

I have problems with my angular, here I have two components:

• MyApp(父组件)
• 登录页面(子组件)

我在 MyApp 部分有一个属性 UserNow，我想通过组件 LoginPage 设置属性 UserNow 的值.怎么做?

I have a property UserNow in parts MyApp and I want to set the value of the property UserNow through the components LoginPage. How to do it?

我尝试过(但没有产生任何影响)

I have tried (but did not give any influence)

Import {MyApp} from '../../app/app.component'; 

@Component({
  selector: 'page-login',
  templateUrl: 'login.html'
})
export class LoginPage {
    public app: any;

    login() {
        ...
        this.app = MyApp;
        this.app.userNow = MyValue;
        ...
    }
}

推荐答案

有几种方法可以做到.

1) 使用服务:服务通常在应用程序中只有一个实例，可用于在组件之间轻松共享数据.例如.创建一个服务 userService 并将其注入到您想要使用它的组件中.

1) Using a service: A service generally has a single instance in the application and can be used to share data between the components easily. E.g. create a service userService and inject it in components where ever you want to use it.

2) using Emit:Emit用于在应用中发出一个事件，可以采取相应的动作.

2) using Emit: Emit is used to emit an event in the application and corresponding action can be taken.

this.eventInChild.emit(data);

可以对事件发射采取两种行动.

Two actions can be taken on event emission.

• 调用父函数:

<child-component (eventInChild)="parentFunction($event)"></child-component>

• 从服务发出并订阅事件(可以在服务和组件中订阅):

在服务中是这样的:

getEmitStatus() {
    return this.eventInService;
}

//In component or service - to listen to event

this.subscription = this.userService.getEmitStatus()
    .subscribe(item => {
         //thing to do here
}); 

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