将输入传递给Angular 2中的嵌套组件

Question

如何将属性从包装组件透明地转换为嵌套组件？

考虑到有

const FIRST_PARTY_OWN_INPUTS = [...];
const FIRST_PARTY_PASSTHROUGH_INPUTS = ['all', 'attrs', 'are', 'passed'];
@Component({
  selector: 'first-party',
  inputs: [...FIRST_PARTY_OWN_INPUTS, ...FIRST_PARTY_PASSTHROUGH_INPUTS],
  template: `
<div>
  <third-party [all]="all" [attrs]="attrs" [are]="are" [passed]="passed"></third-party>
  <first-party-extra></first-party-extra>
</div>
  `,
  directives: [ThirdParty]
})
export class FirstParty { ... }

输入可以批量翻译，这样就不会在模板中枚举？

上面的代码应该重新创建 Angular 1.x 指令的配方：

app.directive('firstParty', function (thirdPartyDirective) {
  const OWN_ATTRS = [...];
  const PASSTHROUGH_ATTRS = Object.keys(thirdPartyDirective[0].scope);

  return {
    scope: ...,
    template: `
<div>
  <third-party></third-party>
  <first-party-extra></first-party-extra>
</div>
    `,
    compile: function (element, attrs) {
      const nestedElement = element.find('third-party');

      for (let [normalizedAttr, attr] of Object.entries(attrs.$attr)) {
        if (PASSTHROUGH_ATTRS.includes(normalizedAttr)) {
          nestedElement.attr(attr, normalizedAttr);
        }
      }
    },
    ...
  };
});

Answer 1

我认为这可以归结为一个没有 Angular2 的更基本的问题。当您有一个需要大量参数的函数时，每次要使用它时都必须指定所有这些参数，这既烦人又容易出错。当有一个根本不关心这些参数的中间函数时，问题会变得更糟——你发现自己向中间函数添加了参数，以便它可以将它传递给内部函数。年！

有几种模式可以处理这个问题。我最喜欢的是完全实例化内部函数并传递已经加载的实例，其中嵌入了以前的传递参数。我认为http://blog.mgechev.com/2016/01/23/angular2-viewchildren-contentchildren-difference-viewproviders/ 是一篇关于如何在 Angular 2 中使用@ViewChild 和@ContentChild 做到这一点的好帖子。另一种策略是将所有传递参数包装在一个对象中，这样至少只有一个参数可以传递。当您想要添加更多参数时，这也很有帮助 - 因为它们已经被打包并以不透明方式传递，所以您的传递代码不需要更改。

Answer 2

您可以通过在子组件上使用 @Input() 来完成此操作。

http://plnkr.co/edit/9iyEsnyEPZ4hBmf2E0ri?p=preview

父组件：

import {Component} from '@angular/core';
import {ChildComponent} from './child.component';

@Component({
  selector: 'my-parent',
  directives: [ChildComponent],
  template: `
    <div>
      <h2>I am the parent.</h2>
      My name is {{firstName}} {{lastName}}.

        <my-child firstName="{{firstName}}" 
                  lastName="{{lastName}}">

        </my-child>

    </div>
  `
})
export class ParentComponent {
  public firstName:string;
  public lastName: string;
  constructor() {
    this.firstName = 'Bob';
    this.lastName = 'Smith';
  }
}

子组件：

import {Component, Input} from '@angular/core';

@Component({
  selector: 'my-child',
  template: `
    <div>
      <h3>I am the child.</h3>
      My name is {{firstName}} {{lastName}} Jr.
      <br/>
     The name I got from my parent was: {{firstName}} {{lastName}}

    </div>
  `
})
export class ChildComponent {
  @Input() firstName: string;
  @Input() lastName: string;
}

应用组件：

//our root app component
import {Component} from '@angular/core';
import {ParentComponent} from './parent.component';

@Component({
  selector: 'my-app',
  directives: [ParentComponent],
  template: `
    <div>
      <my-parent></my-parent>
    </div>
  `
})
export class App {

  constructor() {
  }
}

Answer 3

我不确定我是否做对了，但这是我的实现 (PLUNKER)

---

const FIRST_PARTY_OWN_INPUTS = ['not', 'passthrough'];
const FIRST_PARTY_PASSTHROUGH_INPUTS = ['all', 'attrs', 'are', 'passed'];

const generateAttributes(arr) {
   return arr.map(att => '[' + att + '] = "' + att + '"').join(' ');
}


//-------------------------------------------------------//////////////////
import {Component} from '@angular/core'

@Component({
  selector: 'third-party',
  inputs: [...FIRST_PARTY_PASSTHROUGH_INPUTS],
  template: `
<div>
  {{all}} , {{attrs}} ,  {{are}} ,  {{passed}}
</div>
  `
})
export class ThirdParty {
}

@Component({
  selector: 'first-party',
  inputs: [...FIRST_PARTY_OWN_INPUTS, ...FIRST_PARTY_PASSTHROUGH_INPUTS],
  template: `
<div>
  <div>
    {{not}} , {{passthrough}}
  </div>
  <third-party ${generateAttributes(FIRST_PARTY_PASSTHROUGH_INPUTS)}></third-party>
  <first-party-extra></first-party-extra>
</div>
  `,
  directives: [ThirdParty]
})
export class FirstParty {
}

@Component({
  selector: 'my-app',
  providers: [],
  template: `
    <div>
      <h2>Hello {{name}}</h2>
      <first-party [not]="'not'" [passthrough]="'passthrough'"  
                   [all]="'all'" [attrs]="'attrs'" [are]="'are'" [passed]="'passed'">
      </first-party>
    </div>
  `,
  directives: [FirstParty]
})
export class App {
  constructor() {
    this.name = 'Angular2 (Release Candidate!)'
  }
}

希望对你有帮助:)