Question

我创建了一个类似于ngFor的自定义结构指令。当我尝试使用<template>元素语法来使用它时，模板内部的绑定正在起作用，但是当我使用*语法时，绑定不起作用。

   <!-- working -->
    <template edit [editOf]="values" let-val="val">
      <table >
        <span>This is using template syntax {{val}}</span>
      </table>
    </template>

    <!-- not working -->
      <table *edit="let val1 of values">
        <span>This uses star syntax {{val1}}</span>
      </table>

以下是此问题的plnkr link。

我做错了什么？

更新我想，现在我明白了发生了什么。 let-val被错误地设置为用于绑定的对象的属性val，但我需要整个对象。因此，let-val不应该在模板中分配任何值，然后我将不得不更新上下文。$隐含在viewRef中用作绑定源的对象。

工作plnkr here.

感谢@ robisim74

Answer 1

试试这个：

import {  ChangeDetectorRef,
  Directive,
  Input,
  DoCheck,
  IterableDiffer,
  IterableDiffers,
  TemplateRef,
  ViewContainerRef,
  EmbeddedViewRef} from "@angular/core";

@Directive({
  "selector":"[edit][editOf]"
})
export class EditableTableDirective implements DoCheck {

  private collection:any;
  private differ:IterableDiffer;
  private viewMap:Map<any,EmbeddedViewRef> = new Map<any,EmbeddedViewRef>();

  constructor(
    private changeDetector:ChangeDetectorRef,
              private differs:IterableDiffers,
              private template:TemplateRef,
              private viewContainer:ViewContainerRef){
  }

  @Input() set editOf(coll:any){
    this.collection = coll;
    if (coll && !this.differ) {
      this.differ = this.differs.find(coll).create(this.changeDetector);
    }
  }

  ngDoCheck() {
    if (this.differ) {
      const changes = this.differ.diff(this.collection);
      if (changes) {
        changes.forEachAddedItem((change) => {
          const view = this.viewContainer.createEmbeddedView(this.template, change.item);
          view.context.$implicit = change.item;
          this.viewMap.set(change.item, view);
        });
        changes.forEachRemovedItem((change) => {
          const view = this.viewMap.get(change.item);
          const viewIndex = this.viewContainer.indexOf(view);
          this.viewContainer.remove(viewIndex);
          this.viewMap.delete(change.item);
        });
      }
    }
  }

}

然后更正模板：

<table *edit="let item of values">
   <span>This uses star syntax {{item.val}}</span>
</table>

我遵循了这篇文章：http://teropa.info/blog/2016/03/06/writing-an-angular-2-template-directive.html

Answer 2

 <tr *cpLoop="let cat of categories" (click)="selectCategory(cat)">
                <td>{{cat.categoryId}}</td>
                <td>{{cat.categoryName}}</td>
 </tr>  

 <ng-template cpLoop let-cat [cpLoopOf]="categories" let-i="index">
                 <tr (click)="selectCategory(cat)">                        
                        <td>{{cat.categoryId}}</td>
                        <td>{{cat.categoryName}}</td>
                </tr>            
  </ng-template> 

 @Input() set cpLoopOf(rows:any){
         rows.forEach((row:any, index:any) => {
          let viewRef = this.viewContainer.createEmbeddedView(this.template, row); 
          viewRef.context.$implicit =row;
        });

      }

使用模板输入变量的Angular 2 Custom Structural Directive绑定不起作用

2 个答案: