如何在Angular 6中按默认情况下选择MAT-BUTTON-TOGGLE

Question

i具有反应性的Angular-6形式，其中我使用了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"];

但是在UI中，默认情况下选择了"切换"按钮。

请帮忙，我做错了什么

我的模型就像这样

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

编辑：我希望mat-button-toggle-group也与我的模型结合。

Answer 1

这是一个工作示例：

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(''), })
    });
  }
}