Question

我想从子组件访问父组件上的变量并对其执行某些操作。这是我正在做的事情，但看起来它没有像它想象的那样工作：

parent.ts

import {Component,DynamicComponentLoader,ElementRef,AfterViewInit} from 'angular2/core';
import {bootstrap} from 'angular2/platform/browser';
import {ChildComponent} from './child.ts';


@Component({
    selector: 'app',
    template: `<div #child></div>`
})
class AppComponent implements AfterViewInit{

    public parentValue = "some value."

    constructor(private _loader:DynamicComponentLoader,private _elementRef:ElementRef) {}
    ngAfterViewInit(){
        this._loader.loadIntoLocation(ChildComponent,this._elementRef,'child').then(child => {
            child.instance.log = this.callback;
        });
    }

    callback(){
        console.log(this.parentValue);  //logs undefined rather than "some value"
    }

}

bootstrap(AppComponent);

child.ts

import {Component} from 'angular2/core';

@Component({
    selector: "child-component",
    template: "<button (click)='logParentValue()' >Log Value</button>"
})
export class ChildComponent{
    log:any;
    logParentValue(){
        this.log();
    }
};

当我尝试从子组件记录父组件变量的值时，它始终记录undefined。任何解决方案？

Answer 1

似乎方法的范围不会像传递方式那样保留。

当作为闭合箭头函数传递时它起作用

ngAfterViewInit(){
    this._loader.loadIntoLocation(ChildComponent,this._elementRef,'child').then(child => {
        child.instance.log = () => this.callback();
    });
}

https://plnkr.co/edit/VQ3c2Lv5KEzHUa2ZbGLk?p=preview

Angular2 - 从子组件访问父组件的变量

1 个答案: