是否可以升级angularjs属性指令以在angular 4中使用? [英] Is it possible to upgrade angularjs atttribute directives to use in angular 4?

问题描述

我已经能够升级一个angularjs元素指令以在angular 4中使用. 这是示例代码:

I've been able to upgrade an angularjs element directive to be used in angular 4. Here's a sample code:

[myScores.js]

angular.module('app.components.directives.myScores', [])
.directive('myScores', function() {
  return {
    scope: {
      score: '=',
    },
    template: '<div>&gt;&gt;&gt; Your score is {{score}} &lt;&lt;&lt;',
    link: function(scope) {
      console.log("in myScores", scope)
    }
  };
});

[myScores.ts]

import { Directive, ElementRef, Injector, Input, Output, EventEmitter } from '@angular/core';
import { UpgradeComponent } from '@angular/upgrade/static';

@Directive({
  selector: 'my-scores'
})
export class MyScoresDirective extends UpgradeComponent {
  @Input() score: number;

  constructor(elementRef: ElementRef, injector: Injector) {
    super('myScores', elementRef, injector);
  }
}

注意，我正在使用UpgradeComponent升级myScores元素指令. 我在属性指令上尝试了相同的操作，但是出现了错误.有没有办法升级属性指令?

Notice I'm using UpgradeComponent to upgrade the myScores element directive. I've tried the same on an attribute directive but got an error. Is there a way to upgrade an attribute directive?

这是我升级属性指令的尝试:

Here's my attempt of upgrading an attribute directive:

[makeGreen.js]

angular.module('app.components.directives.makeGreen', [])
.directive('makeGreen', function() {
  return {
    restrict: 'A',
    link: function(scope, element) {
      console.log("in makeGreen", scope)
      console.log("element", element)
      element.css('color', 'green');
    }
  };
});

[makeGreen.ts]

import { Directive, ElementRef, Injector, Input, Output, EventEmitter } from '@angular/core';
import { UpgradeComponent } from '@angular/upgrade/static';

@Directive({
  selector: '[makeGreen]'
})
export class MakeGreenDirective extends UpgradeComponent {
  @Input() count: number;
  @Output() clicked: EventEmitter<number>;

  constructor(elementRef: ElementRef, injector: Injector) {
    console.log("elementRef", elementRef.nativeElement)
    super('makeGreen', elementRef, injector);
  }
}

加载页面时出现错误:

<div makeGreen>Text should be green</div>

我收到此错误:

Error: Directive 'makeGreen' is not a component, it is missing template.

推荐答案

Attribute指令可以完全具有Input属性，可以从使用该属性的标记将其传递给它:例如:

A Attribute directive can totally have the Input property which can be passed to it from the tag where it's used : For ex:

<p highlightThis [highlightColor]="'orange'" [count]="5">Highlighted in orange</p>

还要确保您的appModule/SharedModule导入了它.

Also make sure your appModule/SharedModule imports it.

所以我看到的问题是您定义结构的方式 指示.结构指令没有任何模板结构 附加到它.它适用于使用该标签的任何html标签.

So the problem i see is with the way you are defining your structural directive. A structural directive doesn't have any template structure attached to it. It applies to any html tag where it's used.

对于您来说，我看到您正在使用Component class 扩展指令，而 Attribute指令则不可接受:-

For you case, i see you are extending the directive with Component class which is not acceptable to a Attribute directive :--

MakeGreenDirective extends UpgradeComponent {

您应将属性指令与任何组件分开.例如:

You should keep the Attribute Directive separate from any Component. For Ex:

  import { Directive, ElementRef, Injector, Input, Output, EventEmitter } from 
  '@angular/core';

  @Directive({
    selector: '[highlightThis]'
   })

 export class HighLightThisDirective {
 @Input() count: number;
 @Input() highlightColor: string;
 @Output() clicked: EventEmitter<number>;

 constructor(private elementRef: ElementRef, injector: Injector) {  }

 ngOnInit(): void {
   this.decorateMyTag();
 }

 private decorateMyTag(): void {
   console.log("highlightColor", this.highlightColor);
   this.elementRef.nativeElement.style.backgroundColor = this.highlightColor;
  }
}

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