javascript - Material 扩展面板内容 - ng-template？

Question

我有以下代码，是我从这里偷来的: https://github.com/angular/material2/blob/master/src/demo-app/expansion/expansion-demo.html

  <mat-expansion-panel class="mat-expansion-demo-width" #myPanel>

    <mat-expansion-panel-header [expandedHeight]="expandedHeight" [collapsedHeight]="collapsedHeight">
      <mat-panel-description>Click here to change view format.</mat-panel-description>
      <mat-panel-title>View Controls</mat-panel-title>
    </mat-expansion-panel-header>

    <ng-template matExpansionPanelContent>
      This is the content text that makes sense here.
      <mat-checkbox>Trigger a ripple</mat-checkbox>
    </ng-template>

    foo bar baz

    <mat-action-row>
      <button mat-button (click)="myPanel.expanded = false">CANCEL</button>
    </mat-action-row>
  </mat-expansion-panel>

一个问题-我很困惑，因为<ng-template>里面的内容标签不显示，但显示“foo bar baz”。那么<ng-template>里面的内容是做什么用的呢？为什么不显示？

Answer 1

<ng-template>在您调用它之前不会呈现。试试这个:

<mat-expansion-panel class="mat-expansion-demo-width" #myPanel>

  <mat-expansion-panel-header [expandedHeight]="expandedHeight" [collapsedHeight]="collapsedHeight">
    <mat-panel-description>Click here to change view format.</mat-panel-description>
    <mat-panel-title>View Controls</mat-panel-title>
  </mat-expansion-panel-header>

  <ng-container *ngTemplateOutlet="matExpansionPanelContent"></ng-container>

  foo bar baz

  <mat-action-row>
    <button mat-button (click)="myPanel.expanded = false">CANCEL</button>
  </mat-action-row>
</mat-expansion-panel>

<ng-template #matExpansionPanelContent>                <-- Note the #hashtag
  This is the content text that makes sense here.
  <mat-checkbox>Trigger a ripple</mat-checkbox>
</ng-template>

这样你就可以构建<ng-template>一次，然后在所有地方重复使用它。