如何在 angular2 (ReactiveForms) 中添加动态自定义验证？

Question

我有一个要求，我想实现逻辑来动态地将对象数组数据分配给输入控件，并且基于更新我想更新我的数组，我想触发验证以检查是否输入 names/data在具有重复条目的控件中。为了验证，我使用了 ReactiveForm 模块。但我面临以下 2 个问题 –

我如何创建相同的数组结构以便成功验证我可以直接将更新的结构传递给 api?
我如何将数组对象的 id 分配给 formControlName，目前我正在为它分配循环索引。
plunkar 参考这里 - https://plnkr.co/edit/RSBpT0sFSI1GDCp6K7VR?p=preview

组件：

@Component({
  selector: 'my-app',
  template: `
    <div>
      <h3> Custom Group Validation</h3>
      <form [formGroup]="myForm">
          <div class="left">
              names: <br>
              <div formArrayName="names">
                  <div *ngFor="let item of namesArray.controls; let i = index">
                      <input type="text" [formControlName]="i">
                      <button (click)="removeAt(i)">X</button><br>
                  </div>
              </div>

              <div *ngIf="namesArray.hasError('duplicate')">
                  duplicate entries
              </div>
              <pre>Array value: <br>{{namesArray.value | json}}</pre>
          </div>
      </form>
</div>
  `
})

Class（摘要）：

namesArray:FormArray =  new FormArray([], this.customGroupValidation  );
    dataArray: { custId: number, customerName: string }[] = [
{ custId: 101, customerName: 'John' },
{ custId: 102, customerName: 'Mike' },
{ custId: 103, customerName: 'Julia' }];

    ngOnInit():void{
      for(let ele of this.dataArray){
          this.namesArray.push(
            new FormControl(ele.customerName)
        );
      }
    }

感谢任何帮助！

Answer 1

处理这两个问题的一种方法是订阅 FormGroup 的 .valueChanges 事件，并放入检查方法以验证 FormControl 值是否存在重复情况。

在 ngOnInit() 中创建 FormControl 并将其添加到 FormGroup 时也分配 custId 属性

代码片段 -

import { Component, NgModule, OnInit } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { FormBuilder, FormGroup, FormArray, AbstractControl, Validators, FormControl, ReactiveFormsModule } from '@angular/forms'

@Component({
  selector: 'my-app',
  template: `
    <div>
      <h3> Custom Group Validation</h3>
      <form [formGroup]="customerFormGroup">
          <div class="left">
              names: <br>
              <div>
                  <div *ngFor="let item of dataArray">
                      <input type="text" [formControlName]="item.custId" [(ngModel)]="item.customerName">
                      <div *ngIf="customerFormGroup.controls[item.custId] && customerFormGroup.controls[item.custId].errors">
                        duplicate                       
                      </div>
                  </div>
              </div>
              <pre>Array value: <br>{{dataArray | json}}</pre>
          </div>
      </form>
</div>
  `
})
export class App implements OnInit {
  customerFormGroup: FormGroup = new FormGroup({});
  dataArray: { custId: number, customerName: string }[] = [
    { custId: 101, customerName: 'John' },
    { custId: 102, customerName: 'Mike' },
    { custId: 103, customerName: 'Julia' }];

  ngOnInit(): void {

    for (let ele of this.dataArray) {
      let control: FromControl = new FormControl(ele.customerName);
      this.customerFormGroup.addControl(ele.custId, control);
    }

    this.customerFormGroup.valueChanges.subscribe(
      data => this.onValueChanged(data)
    );
  }

  onValueChanged(data?: any) {
    if (!this.customerFormGroup) return;
    let formGroup = this.customerFormGroup;
    var result = _.groupBy(formGroup.controls, c => {
      if (c.value) return c.value.toLowerCase();
      else c.value;
    });
    for (let prop in result) {
      if (result[prop].length > 1) {
        _.forEach(result[prop], function (item: any) {
          if (item.dirty && item.value) {
            item.setErrors({
              'duplicate': true
            });
          }
        })
      }
    }
  }
}

@NgModule({
  imports: [BrowserModule, ReactiveFormsModule],
  declarations: [App],
  bootstrap: [App]
})
export class AppModule { }

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