angular 2 从基础组件继承 [英] angular 2 inheriting from a base-component
问题描述
我的问题是这里另一个问题的扩展:Angular2 和类继承支持
My question is an extension to another question here on so: Angular2 and class inheritance support
这是我的plunkr:http://plnkr.co/edit/ihdAJuUcyOj5Ze93BwIQ?p=preview
And here is my plunckr: http://plnkr.co/edit/ihdAJuUcyOj5Ze93BwIQ?p=preview
我想要做的是以下内容:
What I am trying to do is the following:
我有一些通用功能，我的所有组件都必须使用这些功能.由于已经在上述问题中得到了回答，因此可以这样做.
I have some common functionallity whcih all of my components will have to use. As it already has been answered in the aforementioned question, this can be done.
我的问题是:我可以在基础组件中注入依赖项吗?在我的 plunkr 中，登录到控制台时未定义声明的依赖项 (FormBuilder).
My question is: Can I have dependencies injected in the base-component? In my plunkr the declared dependency (FormBuilder) is undefined when logged to console.
import {AfterContentChecked, Component, ContentChildren, Input, QueryList, forwardRef, provide, Inject} from '@angular/core';
import { FormGroup, FormControl, Validators, FormBuilder, REACTIVE_FORM_DIRECTIVES } from '@angular/forms';
@Component({
providers: [FormBuilder]
})
export class BaseComponent {
// Interesting stuff here
@Input() id: string;
constructor(formBuilder: FormBuilder){
console.log(formBuilder);
console.log('inside the constructor');
}
}
@Component({
selector: 'child-comp2',
template: '<div>child component #2 ({{id}})</div>',
providers: [provide(BaseComponent, { useExisting: forwardRef(() => ChildComponent2) })]
})
export class ChildComponent2 extends BaseComponent {
}
@Component({
selector: 'child-comp1',
template: '<div>child component #1 ({{id}})</div>',
providers: [provide(BaseComponent, { useExisting: forwardRef(() => ChildComponent1) })]
})
export class ChildComponent1 extends BaseComponent {
}
@Component({
selector: 'parent-comp',
template: `<div>Hello World</div>
<p>Number of Child Component 1 items: {{numComp1}}
<p>Number of Child Component 2 items: {{numComp2}}
<p>Number of Base Component items: {{numBase}}
<p><ng-content></ng-content>
<p>Base Components:</p>
<ul>
<li *ngFor="let c of contentBase">{{c.id}}</li>
</ul>
`
})
export class ParentComponent implements AfterContentChecked {
@ContentChildren(ChildComponent1) contentChild1: QueryList<ChildComponent1>
@ContentChildren(ChildComponent2) contentChild2: QueryList<ChildComponent2>
@ContentChildren(BaseComponent) contentBase: QueryList<BaseComponent>
public numComp1:number
public numComp2:number
public numBase:number
ngAfterContentChecked() {
this.numComp1 = this.contentChild1.length
this.numComp2 = this.contentChild2.length
this.numBase = this.contentBase.length
}
}
@Component({
selector: 'my-app',
template: `<parent-comp>
<child-comp1 id="A"></child-comp1>
<child-comp1 id="B"></child-comp1>
<child-comp2 id="C"></child-comp2>
</parent-comp>
`,
directives: [ParentComponent, ChildComponent1, ChildComponent2]
})
export class MyApplication {
}
推荐答案
这是不可能的，因为 Angular2 只会查看当前组件的注释，而不查看上面组件的注释.
It's not possible the way you do since Angular2 will only have a look at the annotations for the current component but not on the component above.
话虽如此，您可以在注解层面进行工作，使父组件继承注解:
That being said, you can work at the level of annotations to make inherit annotations of the parent component:
export function Inherit(annotation: any) {
return function (target: Function) {
var parentTarget = Object.getPrototypeOf(target.prototype).constructor;
var parentAnnotations = Reflect.getMetadata('design:paramtypes', parentTarget);
Reflect.defineMetadata('design:paramtypes', parentAnnotations, target);
}
}
像这样使用它:
@Inherit()
@Component({
(...)
})
export class ChildComponent1 extends BaseComponent {
constructor() {
super(arguments);
}
}
查看此问题了解更多详情:
See this question for more details:
您可以通过以下文章了解幕后发生的事情:
The following article could interest you to understand what happens under the hood:
您还需要注意，直接处理注释有一些缺点，尤其是在离线编译和 IDE 中的组件自省方面.
You also need to be aware that working on annotations directly has drawbacks especially regarding offline compilation and for component introspection in IDEs.
这篇关于angular 2 从基础组件继承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！
