angular2在一个元素上不能有多个模板绑定

Question

我有这个angular2模板:

<template *ngIf="alerts.length > 0">
<alert *ngFor="let alert of alerts;let i = index" [type]="alert.type" dismissible="true" (close)="closeAlert(i)">
  {{ alert?.msg }}
</alert>
  </template>

我收到这些错误:

zone.js:461 Unhandled Promise rejection: Template parse errors:
Can't have multiple template bindings on one element. Use only one attribute named 'template' or prefixed with * (" </div>
  <div *ngSwitchCase="false" class="container p-t-10">
    <alert *ngIf="alerts.length > 0" [ERROR ->]*ngFor="let alert of alerts;let i = index" [type]="alert.type" dismissible="true" (close)="closeAlert"): b@5:37

我把*ngIf和*ngFor放在不同的html元素中是什么问题.它应该工作.没有？

和:

Can't bind to 'type' since it isn't a known property of 'alert'. (""container p-t-10">
    <alert *ngIf="alerts.length > 0" *ngFor="let alert of alerts;let i = index" [ERROR ->][type]="alert.type" dismissible="true" (close)="closeAlert(i)">
      {{ alert?.msg }}
    </alert>
"): b@5:80

我加了

*ngIf="alerts.length > 0避免的情况alert = [].我该怎么办呢？

Answer 1

将*在*ngFor使角添加一个<template>标签.在<template>标签上这没有意义,因此这里结构指令具有不同的语法.

<template ngFor [ngForOf]="alerts" let-alert let-i="index">

因为在不同的地方几乎相同的不同语法引起了相当多的混乱,Angular团队最近介绍了

<ng-container>

行为类似于<template>标记(未添加到DOM)但允许更常见的语法

<ng-container *ngIf="alerts.length > 0">
  <alert *ngFor="let alert of alerts;let i = index" [type]="alert.type" dismissible="true" (close)="closeAlert(i)">
    {{ alert?.msg }}
  </alert>
</ng-container>