Angular2 级联 Select

Question

在 Angular2 中，我想为给定的 xs 和 ys 数组对象创建级联 select：

data:Array<Object> = 
  [
    {"x":50, "ys":[ 10, 15, 20, 25, 30, 35]},                                                                                                           
    {"x":75, "ys":[ 15,20,25,30,35,40,45]}
  ];

第一个 select 填充 x，第二个填充相应的 ys。

以下是 x 的 select 代码。

  <select [(ngModel)]="x"> 
    <option *ngFor="#n of data" [attr.value]="n.x">{{n.x}}</option>
  </select>

如何根据选择的x值用ys填充第二个select？

我创建了一个plunkr

Answer 1

这可能是您要找的：

@Component({
  selector: 'my-app',
  providers: [],
  template: `
<select [(ngModel)]="x"> 
  <option *ngFor="let n of data" [ngValue]="n.x">{{n.x}}</option>
</select>

<select [(ngModel)]="y"> 
  <option *ngFor="let n of data[x == 50 ? 0 : 1].ys" [ngValue]="n">{{n}}</option>
</select>

<div>{{data[x == 50 ? 0 : 1].ys}}</div>

  `,
  directives: []
})
export class App {
  x = 50;
data:Array<Object> = [
    {"x":50, "ys":[ 10, 15, 20, 25, 30, 35]},                                                                                                           
    {"x":75, "ys":[ 15,20,25,30,35,40,45]}
  ];
}

Plunker example

Answer 2

我会像这样利用 selectedIndex：

<select [ngModel]="x" (ngModelChange)="x = $event; second.selectedIndex = 0" #first> 
   <option *ngFor="#n of data" [attr.value]="n.x">{{n.x}}</option>
</select>
<select [(ngModel)]="y" #second> 
   <option *ngFor="#n of data[first.selectedIndex].ys" [attr.value]="n">{{n}}</option>
</select>
...
export class App {
  x: number = 50;

  y: number = 10;

  data:Array<Object> = 
  [
    {"x":50, "ys": [10, 15, 20, 25, 30, 35]},                                                                                                           
    {"x":75, "ys": [15, 20, 25, 30, 35, 40, 45]},
    {"x":100, "ys": [25, 35, 40, 45, 55, 65]} 
  ];
}

另请参阅工作示例 https://plnkr.co/edit/W3avXWmcmWFpBhS14LGP?p=preview

语义UI版本在这里https://plnkr.co/edit/4TIdWBNwk0wKR4ndKdzJ?p=preview

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