Angular 5，Angular Material 复选框，有 3 种状态(选中、未选中、不确定) [英] Angular 5, Angular Material Checkbox with 3 states (checked, unchecked, indeterminate)

问题描述

我是 Angular 和 Angular Material 的新手，现在我在某个项目中担任支持人员.有一个带有过滤器的网格和一个复选框，用于检查网格中的用户是处于活动状态、非活动状态还是未被选中.只有两个选项(活动、非活动)会更简单，但是我必须为它设置 3 个状态:

I'm new to Angular and Angular Material, now I'm working as a support in some project. There's a grid with filters and one checkbox, which checks if user in grid is active, inactive, or not chosen. It would be simpler with only two options (active, inactive) but well, I have to make 3 states for it:

1. 第 1 次点击 - 检查是否有效
2. 第二次点击 - 未选中处于非活动状态
3. 第 3 次点击 - 未选择不确定

这是来自官方 Angular Material 文档的复选框示例:https://stackblitz.com/angular/rxdmnbxmkgk?file=app%2Fcheckbox-configurable-example.html

Here is checkbox example from official Angular Material documentation: https://stackblitz.com/angular/rxdmnbxmkgk?file=app%2Fcheckbox-configurable-example.html

如何以最简单的方式制作?

How to make it in the most simply way?

推荐答案

@angular/material >= 9

这是一个现成的组件:

import { Component, forwardRef, Input } from '@angular/core';
import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';
import { MatCheckboxDefaultOptions, MAT_CHECKBOX_DEFAULT_OPTIONS } from '@angular/material/checkbox';

@Component({
  selector: 'app-tri-state-checkbox',
  templateUrl: './tri-state-checkbox.component.html',
  styleUrls: ['./tri-state-checkbox.component.scss'],
  providers: [
    {
      provide: NG_VALUE_ACCESSOR,
      useExisting: forwardRef(() => TriStateCheckboxComponent),
      multi: true,
    },
    { provide: MAT_CHECKBOX_DEFAULT_OPTIONS, useValue: { clickAction: 'noop' } as MatCheckboxDefaultOptions },
  ],
})
export class TriStateCheckboxComponent implements ControlValueAccessor {

  @Input() tape = [null, true, false];

  value: any;

  disabled: boolean;

  private onChange: (val: boolean) => void;
  private onTouched: () => void;

  writeValue(value: any) {
    this.value = value || this.tape[0];
  }

  setDisabledState(disabled: boolean) {
    this.disabled = disabled;
  }

  next() {
    this.onChange(this.value = this.tape[(this.tape.indexOf(this.value) + 1) % this.tape.length]);
    this.onTouched();
  }

  registerOnChange(fn: any) {
    this.onChange = fn;
  }

  registerOnTouched(fn: any) {
    this.onTouched = fn;
  }

}

和模板:

<mat-checkbox [ngModel]="value" (click)="next()" [disabled]="disabled" [indeterminate]="value === false" [color]="value === false ? 'warn' : 'accent'">
  <ng-content></ng-content>
</mat-checkbox>

用法:

<app-tri-state-checkbox [(ngModel)]="done">is done</app-tri-state-checkbox>
<app-tri-state-checkbox formControlName="done">is done</app-tri-state-checkbox>

您还可以将默认磁带覆盖为例如枚举值:

You can also override default tape to e.g. enum values:

<app-tri-state-checkbox [tape]="customTape" [(ngModel)]="done">is done</app-tri-state-checkbox>

其中 customTape 替换默认值 [null, true, false]

customTape = [Status.open, Status.complete, Status.cancelled];

@angular/material <= 8

只要改变

{ provide: MAT_CHECKBOX_DEFAULT_OPTIONS, useValue: { clickAction: 'noop' } as MatCheckboxDefaultOptions },

自第 9 版起已弃用 MAT_CHECKBOX_CLICK_ACTION

to the deprecated since version 9 MAT_CHECKBOX_CLICK_ACTION

{ provide: MAT_CHECKBOX_CLICK_ACTION, useValue: 'noop' },

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