ngOnChanges在输入属性更改时不触发 [英] ngOnChanges not firing when input property changed

问题描述

在angular2中更改零部件属性时，可以通过编程方式触发角度变化检测吗?

Can you programatically trigger angular's change detection when mutating a component property in angular2?

@Component({
   selector: 'my-component', 
})
class MyComponent implements OnChanges {
   @Input() message: string;

   ngOnChanges(changeRecord) {
      for (var change in changeRecord) {
         console.log('changed: ' + change);
      }
   }

   doSomething() {
     // I want ngOnChanges to be called some time after I set the 
     // message. Currently it is only called if the host element
     // changes the value of [message] on the element.
     this.message = 'some important stuff';
   }
}

推荐答案

尝试手动调用更改检测或花费大量时间解决此问题，这是一种过大的方法，为什么不创建一个函数来处理所需的突变并调用在ngOnChanges和doSomething中都可以吗?像这样:

Trying to manually call change detection or spent a lot of time on a workaround for this is way overkilling, why not creating a function to handle the desired mutation and call it in both ngOnChanges and doSomething? something like:

@Component({
  selector: 'my-component',
})
class MyComponent implements OnChanges {
  @Input() message: string;
  viewMessage: string;

  ngOnChanges(changes: { [propertyName: string]: SimpleChange }) {
    for (let propName in changes) {
      if (propName === 'message') {
        this.updateView(this.message);
      }
    }
  }

  doSomething() {
    this.viewMessage = 'some important stuff';
  }

  updateView(message: string) {
    this.viewMessage = message;
  }
}

所以viewMessage将是您将要使用和控制模板的属性.

So viewMessage will be the attribute you'll be using and controlling the template.

这篇关于ngOnChanges在输入属性更改时不触发的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！