角材料自动完成力选择 [英] Angular Material Autocomplete force selection

问题描述

在我的angular 5应用程序中，我有一些matAutocomplete，但是我想强制选择没有建议的内容，因此我遵循这种方法: stackblitz 但由于某种原因，我遇到了一个问题:

In my angular 5 application I have some matAutocomplete, but I want to force the selection of oone of suggestions, so I am following this approach: stackblitz but for some reason in one case I have an issue:

无法读取未定义的属性"panelClosingActions" 在CustomerDetailComponent.countryClosingActions(customer-detail.component.ts:199) 在CustomerDetailComponent.ngAfterViewInit

Cannot read property 'panelClosingActions' of undefined at CustomerDetailComponent.countryClosingActions (customer-detail.component.ts:199) at CustomerDetailComponent.ngAfterViewInit

我有多个matAutocomplete，但是只有一个有问题. (有关此方法的信息，请参见 github

I have multiple matAutocomplete but only this one have problems. (info about this method is here github

html

<mat-form-field>
    <input matInput #nation placeholder="{{'customer.detail.labels.country'
      | translate }}" required [matAutocomplete]="tdAuto" name="country"  
      #count="ngModel" [(ngModel)]="selected.country"
      (ngModelChange)="searchCountry($event)">
        <mat-autocomplete #tdAuto="matAutocomplete" [displayWith]="displayFn">
          <mat-option (onSelectionChange)="setCountry(country)" *ngFor="let country of countries" [value]="country">
             <div class="row">
               <img src="assets/img/flags24/{{country.alpha2Code | lowercase}}.png" />
                  <span>{{country.name}} ({{country.alpha2Code}})</span>
             </div>
         </mat-option>
        </mat-autocomplete>
    </mat-form-field>

组件

@ViewChild('nation', { read: MatAutocompleteTrigger }) trigger: MatAutocompleteTrigger;
  subscription: Subscription;


ngAfterViewInit() {
    this.countryClosingActions();
  }

  private countryClosingActions(): void {
    if (this.subscription && !this.subscription.closed) {
      this.subscription.unsubscribe();
    }

    this.subscription = this.trigger.panelClosingActions
      .subscribe(e => {
        console.log('closing')
        if (!e || !e.source) {
          this.selected.country = null;
          this.selfCountry = null;
        }
      },
      err => this.countryClosingActions(),
      () => this.countryClosingActions());
  }

推荐答案

使用模糊事件和matAutocomplete输出事件(optionSelected)，可以强制用户选择选项.

Using blur event and matAutocomplete output event (optionSelected) we can force user to select option.

<mat-form-field class="example-full-width">
  <input type="text" placeholder="Country*" matInput formControlName="country" [matAutocomplete]="countryAutoList" (blur)="checkCountry()">
  <mat-autocomplete autoActiveFirstOption #countryAutoList="matAutocomplete" (optionSelected)="countryClick($event)">
    <mat-option *ngFor="let item of countryList" [value]="item.Name">{{item.Name}}</mat-option>
  </mat-autocomplete>
</mat-form-field>

ts文件功能

countryClick(event: any) {
  this.selectedCountry = event.option.value;
}

checkCountry() {
  if (!this.selectedCountry || this.selectedCountry !== this.signatureFormGroup.controls['country'].value) {
    this.signatureFormGroup.controls['country'].setValue(null);
    this.selectedCountry = '';
  }
}

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