Angular组件库ng-zorro-antd实现radio单选框选择

目录

• antd组件库升级之后代码不生效
• 解决方法
• 总结

antd组件库升级之后代码不生效

项目业务之前的代码设计了类似radio单选框取消选择的相关逻辑，用的是下面类似的代码实现的。但近期对ng-zorro-antd组件库升级之后，下面的代码不生效了。

import { Component } from '@angular/core';
@Component({
  selector: 'nz-demo-radio-radiogroup',
  template: `
    <nz-radio-group [(ngModel)]="radioValue">
      <label nz-radio (click)="click('A')" nzValue="A">A</label>
      <label nz-radio nzValue="B">B</label>
      <label nz-radio nzValue="C">C</label>
      <label nz-radio nzValue="D">D</label>
    </nz-radio-group>
  `
})
export class NzDemoRadioRadiogroupComponent {
  radioValue = 'A';
  click(value: any) {
    if (this.radioValue === value) {
      this.radioValue = ''
    }
  }
}

于是我到组件库源码里去找原因，并写demo打断点调试

• 将nz-radio-group绑定的radioValue值清空会首先走group组件下面的逻辑

writeValue(value: NzSafeAny): void {
    this.value = value;
    this.nzRadioService.select(value);
    this.cdr.markForCheck();
  }

• nz-radio 和 nz-radio-group都是共用这个NzRadioService，且组件内init时都有对selected$这个流做监听

@Injectable()
export class NzRadioService {
  selected$ = new ReplaySubject<NzSafeAny>(1);
  touched$ = new Subject<void>();
  disabled$ = new ReplaySubject<boolean>(1);
  name$ = new ReplaySubject<string>(1);
  touch(): void {
    this.touched$.next();
  }
  select(value: NzSafeAny): void {
    this.selected$.next(value);
  }
  setDisabled(value: boolean): void {
    this.disabled$.next(value);
  }
  setName(value: string): void {
    this.name$.next(value);
  }
}
// radio.component.ts ====> ngOnInit
this.nzRadioService.selected$.pipe(takeUntil(this.destroy$)).subscribe(value => {
        const isChecked = this.isChecked;
        this.isChecked = this.nzValue === value;
        // We don't have to run `onChange()` on each `nz-radio` button whenever the `selected$` emits.
        // If we have 8 `nz-radio` buttons within the `nz-radio-group` and they're all connected with
        // `ngModel` or `formControl` then `onChange()` will be called 8 times for each `nz-radio` button.
        // We prevent this by checking if `isChecked` has been changed or not.
        if (
          this.isNgModel &&
          isChecked !== this.isChecked &&
          // We're only intereted if `isChecked` has been changed to `false` value to emit `false` to the ascendant form,
          // since we already emit `true` within the `setupClickListener`.
          this.isChecked === false
        ) {
          this.onChange(false);
        }
        this.cdr.markForCheck();
      });

• 当监听完值改变后，后面又执行了radio的click事件，把点击哪个radio的value值传过去了，所以之前的清空值操作就被覆盖了。

private setupClickListener(): void {
    this.ngZone.runOutsideAngular(() => {
      fromEvent<MouseEvent>(this.elementRef.nativeElement, 'click')
        .pipe(takeUntil(this.destroy$))
        .subscribe(event => {
          /** prevent label click triggered twice. **/
          event.stopPropagation();
          event.preventDefault();
          if (this.nzDisabled || this.isChecked) {
            return;
          }
          this.ngZone.run(() => {
            // !!! again  
            this.nzRadioService?.select(this.nzValue);
            if (this.isNgModel) {
              this.isChecked = true;
              this.onChange(true);
            }
            this.cdr.markForCheck();
          });
        });
    });
  }

解决方法

清空值的操作加setTimeout 使组件库内部先执行完click后续再执行。

import { Component } from '@angular/core';
@Component({
selector: 'nz-demo-radio-radiogroup',
template: `
  <nz-radio-group [(ngModel)]="radioValue">
    <label nz-radio (click)="click('A')" nzValue="A">A</label>
    <label nz-radio nzValue="B">B</label>
    <label nz-radio nzValue="C">C</label>
    <label nz-radio nzValue="D">D</label>
  </nz-radio-group>
`
})
export class NzDemoRadioRadiogroupComponent {
radioValue = 'A';
click(value: any) {
  if (this.radioValue === value) {
    setTimeout(()=>{
      this.radioValue = ''
    })
  }
}
}

总结

其实组件库单选radio本身是不支持取消选择的，正解应该是用checkbox实现相关的业务逻辑才对，但很久之前的业务逻辑涉及到很多地方的修改，此时再换checkbox并且换样式的话，改动的还是比较大的，就先简单解决这个问题。