如何在angular2（ReactiveForms）中添加动态自定义验证？

Question

我有要求，我想在哪里实现逻辑以动态地将对象数组数据分配给输入控件，并基于更新，我想更新数组以及触发验证以检查控件中输入的名称/数据是否具有重复条目。 为了进行验证，我使用了ReactiveForm模块。 但我面临以下2个问题–

1. 如何创建相同的数组结构，以便在成功验证后可以将更新后的结构直接传递给api？
2. 我如何将数组对象的id分配给formControlName，目前我正在用循环索引分配它。
   这里的plunkar参考-https://plnkr.co/edit/RSBpT0sFSI1GDCp6K7VR?p = preview

零件：

@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>
  `
})

课程（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)
        );
      }
    }

任何帮助表示赞赏！

Answer 1

处理这两个问题的一种方法是订阅.valueChanges事件，然后使用check in方法来验证FormControl值是否存在重复条件。

在ngOnInit（）中创建FormControl并将其添加到FormGroup时，还要分配custId属性

代码段-

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 { }