如何在 Angular Material 中将制表键作为输入键？

Question

这是我的角度材料自动完成代码

<input type="search" id="setId" name="setId" [attr.list]='collectionType' [(ngModel)]="selValue" class="text-box"
  placeholder="--Select--" (focus)="ValidateParent()" (keyup.tab)="test()" (keyup)="EmitValues($event)" [id]="setId"
  [matAutocomplete]="auto" [title]="selValue" [placeholder]='WaterMarkText'>


<div [hidden]="IsCascading">
  <mat-autocomplete [id]="collectionType" #auto="matAutocomplete" (optionSelected)='onChange($event)'>
    <mat-option *ngFor="let items of codeList" [value]="items.text" [attr.data-text]='items.text' [id]="items.value">
      {{items.text}}
    </mat-option>
  </mat-autocomplete>
</div>

Angular 材质在tab 选择方面存在问题。比如单击tab 按钮时，材质自动完成无法选择值。但它在单击enter 按钮时工作。因此，我需要手动覆盖tab 键事件上的enter 键事件。怎么可能？

Answer 1

改进我的评论，根据回复我们可以创建一个指令

import {
    Directive,
    AfterViewInit,
    OnDestroy,
    Optional
} from '@angular/core';
import {
    MatAutocompleteTrigger
} from '@angular/material';


@Directive({
    selector: '[tab-directive]'
})
export class TabDirective implements AfterViewInit, OnDestroy {
    observable: any;
    constructor(@Optional() private autoTrigger: MatAutocompleteTrigger) {}
    ngAfterViewInit() {
        this.observable = this.autoTrigger.panelClosingActions.subscribe(x => {
            if (this.autoTrigger.activeOption) {
                this.autoTrigger.writeValue(this.autoTrigger.activeOption.value)
            }
        })
    }
    ngOnDestroy() {
        this.observable.unsubscribe();
    }
}

你使用：

<input tab-directive type="text" matInput [formControl]="myControl" 
      [matAutocomplete]="auto" >

（见stackblitz）

更新我们只能控制tab.key，否则你总是关闭，你得到选择的值，所以

@Directive({
    selector: '[tab-directive]'
})
export class TabDirective {
    observable: any;
    constructor(@Optional() private autoTrigger: MatAutocompleteTrigger) {}

    @HostListener('keydown.tab', ['$event.target']) onBlur() {
        if (this.autoTrigger.activeOption) {
            this.autoTrigger.writeValue(this.autoTrigger.activeOption.value)
        }
    }

}

(see a new stackblitz)

更新 2 我不相信这个答案有这么多赞成，因为它是错误的。作为@Andrew allen cmets，该指令不会更新控件。好吧，已经晚了，但我试图解决。一种选择是使用

this.autoTrigger._onChange(this.autoTrigger.activeOption.value)

另一个想法是注入 ngControl，所以

constructor(@Optional() private autoTrigger: MatAutocompleteTrigger,
    @Optional() private control: NgControl) {}
ngAfterViewInit() {
    this.observable = this.autoTrigger.panelClosingActions.subscribe(x => {
        if (this.autoTrigger.activeOption) {
            const value = this.autoTrigger.activeOption.value;
            if (this.control)
                this.control.control.setValue(value, {
                    emit: false
                });
            this.autoTrigger.writeValue(value);
        }
    })
}

Answer 2

我参加聚会有点晚了；所以 Eliseo 的回答有一个烦人的问题：即使用户已经通过鼠标单击从面板中选择了不同的选项，它也会自动完成。我最终想出的解决方法一点也不直截了当。

    /**
     * Selects currently active item on TAB
     * @example
     * <input vxTabActiveOption [matAutocomplete]="matAutocomplate">
     * <mat-autocomplete #matAutocomplate="matAutocomplete" autoActiveFirstOption>
     */
    @Directive({ selector: '[vxTabActiveOption]' })
    export class TabActiveOptionDirective implements AfterViewInit, OnDestroy {
      private readonly destroy$ = new Subject<void>();
    
      /**
       * Whether or not the autocomplete panel was open before the event
       */
      private panelOpen = false;
    
      constructor(
        private autoTrigger: MatAutocompleteTrigger,
        private control: NgControl
      ) { }
    
      ngAfterViewInit() {
        const autocomplete = this.autoTrigger.autocomplete;
        merge(
          autocomplete.opened.pipe(map(() => true)),
          autocomplete.closed.pipe(map(() => false))
        ).pipe(
          takeUntil(this.destroy$),
          delay(0)
        ).subscribe(value => this.panelOpen = value);
      }

      @HostListener('keydown.tab')
      onBlur() {
        if (this.panelOpen && this.autoTrigger.activeOption) {
          const value = this.autoTrigger.activeOption.value;
          this.control.control.setValue(value, { emit: false });
          this.autoTrigger.writeValue(value);
        }
      }
    
      ngOnDestroy() {
        this.destroy$.next();
        this.destroy$.complete();
      }
    }

Answer 3

是的，我知道这是一个老问题，但有一个更好的方法是使用类似的指令

@Directive({ selector: '[tab-selected]' })
export class TabSelected implements AfterViewInit {
  constructor(private auto: MatAutocomplete) {}
  ngAfterViewInit() {
    this.auto._keyManager.onKeydown = (event: KeyboardEvent) => {
      switch (event.keyCode) {
        case TAB:
          if (this.auto.isOpen) {
            const option = this.auto.options.find(x => x.active);
            if (option) {
              option.select();
              event.preventDefault();
              return;
            }
          }
          this.auto._keyManager.tabOut.next();
          break;
        case DOWN_ARROW:
          this.auto._keyManager.setNextItemActive();
          break;

        case UP_ARROW:
          this.auto._keyManager.setPreviousItemActive();
          break;
      }
    };
  }
}

你用喜欢

<mat-form-field class="example-full-width" appearance="fill">
  <mat-label>Number</mat-label>
  <input type="text"
         placeholder="Pick one"
         aria-label="Number"
         matInput
         [formControl]="myControl"
         [matAutocomplete]="auto">
  <mat-autocomplete tab-selected #auto="matAutocomplete"
  autoActiveFirstOption >
    <mat-option  *ngFor="let option of filteredOptions | async" [value]="option">
      {{option}}
    </mat-option>
  </mat-autocomplete>
</mat-form-field>

您可以在this stackblitz工作