如何将自定义验证器添加到FormArray? [英] How to add custom validator to a FormArray?

问题描述

我想添加自定义验证器以防止表单切换到下一步.当我使用FormGroups时，一切都很好，但是当我必须使用FormArray时，我无法实现验证.

I want to add custom validator to form in order to prevent mat-step switching to next step. All works well when I use FormGroups but I fail to achieve validation when I have to use FormArray.

我已经尝试过至少两种在表单初始化时分配验证器的变体:

I've tried at least two variants of assigning validator on form initialization:

• 内部数组

statuses: this._formBuilder.array([this.createStatus()], defaultStatusValidator())

• 内部父级数组

this.productionLineStatuses = this._formBuilder.group({statuses: this._formBuilder.array([this.createStatus()])}, {validator: defaultStatusValidator()});

this.productionLineStatuses = this._formBuilder.group({statuses: this._formBuilder.array([this.createStatus()])}, {validator: defaultStatusValidator()});

但是这种尝试会导致错误(可能是在投放验证器时):

But this attempts are causing error (probably when casting validator):

TypeError: Cannot convert undefined or null to object 
    at Function.keys (<anonymous>)
    at FormGroup.validate [as validator] (default-status.directive.ts:6)
    at FormGroup._runValidator (forms.js:3438)
    at FormGroup.updateValueAndValidity (forms.js:3399)
    at new FormGroup (forms.js:4097)
    at FormBuilder.group (forms.js:7578)
    at CreateProductionLineComponent.ngOnInit (create-production-line.component.ts:31)

在以下情况下，不会引发错误，但是验证器也无法正常工作. 这是我的代码其余部分和自定义验证器:

In the following case error is not thrown, but validator is not working too. Here is rest of my code and my custom validator:

ngOnInit() {
    this.productionLineDetails = this._formBuilder.group({
      productType: ['', Validators.required],
      language: ['', Validators.required],
      name: ['', Validators.required],
      description: [''],
    });
    this.productionLineStatuses = this._formBuilder.group({
      statuses: this._formBuilder.array([
        this.createStatus()
      ])
    }, defaultStatusValidator());
    this.statuses = this.productionLineStatuses.get('statuses') as FormArray;
    this.statusError = false;
  }

验证器:

export function defaultStatusValidator(): ValidatorFn {
    return function validate (statuses: FormArray) {
    let defaultCounter = 0;
    Object.keys(statuses.value.controls).forEach(key => {
        const control = statuses.value.controls[key];

        if (control.value.default == true) {
            defaultCounter ++;
        }
      });
    return (defaultCounter > 1) ? {moreThanOneStatusIsDefault: true} : null;
    };
}

我应该如何正确地将验证器添加到FormArray?

How should I properly add validator to FormArray?

推荐答案

您已经考虑过FormArray是FormControls的FormArray还是FormGroups的FormArray，但是问题是如何遍历控件，

You has consider if your FormArray is a FormArray of FormControls or a FormArray of FormGroups, but the problem is how you iterate over the controls,

两者的简单示例

export function customValidateArray(): ValidatorFn {
    return (formArray:FormArray):{[key: string]: any} | null=>{
      let valid:boolean=true;
      formArray.controls.forEach((x:FormControl)=>{
          valid=valid && x.value=="a"
      })
      return valid?null:{error:'Not all a'}
    }
  };

export function customValidateArrayGroup(): ValidatorFn {
    return (formArray:FormArray):{[key: string]: any} | null=>{
      let valid:boolean=true;
      formArray.controls.forEach((x:FormGroup)=>{
          valid=valid && x.value.name=="a" 
      })
      return valid?null:{error:'Not all name are a'}
    }
  };

您可以在 stackblitz 中查看示例a>

You can see an example in stackblitz

注意:要创建表单，我使用FormGroup，FormControl和FormArray的构造函数，但您也可以使用FormBuilder.

NOTE: To create the form, I use the constructor of FormGroup, FormControl and FormArray, but you can use FormBuilder too.

注意2:不必将FormArray放在FormGroup中

NOTE 2: it's not necesary enclose a FormArray in a FormGroup

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