Angular 2: *ngFor in *ngFor

问题

The following scenario would be pretty easy in javascript but I got some problems getting it worked in Angular.

I got an Array like:

array a = ( "id" = 0, name = random(), column = 1, 2 or 3, blockrow= 1, 2 or 3)

With ngFor I try to create now a grid there all elements out of a get separated in colums and blocks in this column. So my current code (works but nasty).

<div *ngFor="let a of a">
  <template [ngIf]="a.column=='1'">
    <div *ngFor="let b of a">
      <template [ngIf]="b.blockrow=='1'">
        Block 1 in column 1{{b.name}}
      </template>
    </div>
    <div *ngFor="let b of a">
      <template [ngIf]="b.blockrow=='2'">
        Block 2 in column 1{{b.name}}
      </template>
    </div>
    <div *ngFor="let b of a">
      <template [ngIf]="b.blockrow=='3'">
        Block 3 in column 1{{b.name}}
      </template>
    </div>
  </template>
</div>

Something like this do I run for every column. Which means I loop trough the same array for 12 times. Is there any way to do it more beautifull ?

回答1:

In your component, use JavaScript to build an array of arrays with the elements of a at the right coordinates, then use *ngFor inside *ngFor:

<div *ngFor="let row of rows">
  <div *ngFor="let col of row">
    Block {{col.blockrow}} in column {{col.column}} {{col.name}}
  </div>
</div>

A third *ngFor might be needed if several blocks have the same coordinates.

回答2:

You are using wrong syntax should be *ngIf instead of [ngIf]

<div *ngFor="let a of a">
  <template *ngIf="a.column=='1'">
    <div *ngFor="let b of a">
      <template *ngIf="b.blockrow=='1'">
        Block 1 in column 1{{b.name}}
      </template>
    </div>
    <div *ngFor="let b of a">
      <template *ngIf="b.blockrow=='2'">
        Block 2 in column 1{{b.name}}
      </template>
    </div>
    <div *ngFor="let b of a">
      <template *ngIf="b.blockrow=='3'">
        Block 3 in column 1{{b.name}}
      </template>
    </div>
  </template>
</div>

来源：https://stackoverflow.com/questions/43580067/angular-2-ngfor-in-ngfor

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angular

ngfor