如何在angular 6中默认选中垫子按钮切换

Question

我有一个反应式的angular-6表单，在这个表单中，我使用了mat-button-toggle group

<mat-button-toggle-group #group="matButtonToggleGroup"  [(value)]="myFlagForButtonToggle" (change)="onEndpointValChange(group.value)"  multiple=false formControlName='endpoints' [(ngModel)]="myFlagForButtonToggle">
          <mat-button-toggle  *ngFor="let item of endpointToggleOptions;" [value]="item">{{item}}</mat-button-toggle>
</mat-button-toggle-group>

在ts文件中我有

  myFlagForButtonToggle: String[] = ["Single"];
  endpointToggleOptions: Array<String> = ["Single", "Multiple"];

但在UI中，切换按钮的编号默认处于选中状态。

请帮帮忙，我做错了什么？

我的模型是这样的

this.outerForm = this._formBuilder.group({
  firstFormGroup: this._formBuilder.group({
    pidNumber: ['', [Validators.pattern(this.spacePattern)]],
  }),
  secondFormGroup: this._formBuilder.group({
    endpoints: ['', [Validators.required]]
  })
});

编辑:我想让mat-button-toggle group也与我的模型绑定。

Answer 1

Here是一个工作示例：

HTML代码：

<form [formGroup]="outerForm">
    <div formGroupName="secondFormGroup">
        <mat-button-toggle-group #group="matButtonToggleGroup" (change)="onEndpointValChange(group.value)" multiple="false" formControlName='endpoints'
         [(ngModel)]="myFlagForButtonToggle">
            <mat-button-toggle *ngFor="let item of endpointToggleOptions;" [value]="item">{{item}}</mat-button-toggle>
        </mat-button-toggle-group>
    </div>
</form>

TS代码：

import { Component } from '@angular/core';

import { FormGroup, FormBuilder, Validators, FormControl } from '@angular/forms';

/**
 * @title Exclusive selection
 */
@Component({
  selector: 'button-toggle-exclusive-example',
  templateUrl: 'button-toggle-exclusive-example.html',
  styleUrls: ['button-toggle-exclusive-example.css'],
})
export class ButtonToggleExclusiveExample {

  myFlagForButtonToggle: String = "Single";
  endpointToggleOptions: Array<String> = ["Single", "Multiple"];
  outerForm: FormGroup;
  constructor(private _formBuilder: FormBuilder) {
    this.outerForm = this._formBuilder.group({
      firstFormGroup: this._formBuilder.group({ pidNumber: new FormControl(''), }), secondFormGroup:
        this._formBuilder.group({ endpoints: new FormControl(''), })
    });
  }
}