Angular-动态添加/删除验证器

问题描述

我有一个FormGroup定义，如下所示:

I have a FormGroup defined like below:

this.businessFormGroup: this.fb.group({
    'businessType': ['', Validators.required],
    'description': ['', Validators.compose([Validators.required, Validators.maxLength(200)])],
    'income': ['']
  })

现在，当businessType是Other时，我想从description中删除Validators.required验证器.如果businessType不是Other，我想添加回Validators.required.

Now when businessType is Other , I want to remove Validators.required validator from description. And if businessType is not Other, I want to add back the Validators.required.

我正在使用以下代码动态添加/删除Validators.required.但是，它会清除现有的Validators.maxLength验证器.

I am using the below code to dynamically add/remove the Validators.required. However, it clears the existing Validators.maxLength validator.

if(this.businessFormGroup.get('businessType').value !== 'Other'){
    this.businessFormGroup.get('description').validator = <any>Validators.compose([Validators.required]);               
} else {                
    this.businessFormGroup.get('description').clearValidators();               
}

this.businessFormGroup.get('description').updateValueAndValidity(); 

我的问题是，添加/删除required验证器时如何保留现有验证器.

My question is, how can I retain the existing validators when adding/removing the required validator.

推荐答案

角度表单具有内置函数 setValidators()，可通过程序分配验证程序.

Angular forms have a built in function setValidators() that enables programmatic assignment of Validators.

对于您的示例，您可以执行以下操作:

For your example you can do:

if(this.businessFormGroup.get('businessType').value !== 'Other'){
    this.businessFormGroup.controls['description'].setValidators([Validators.required, Validators.maxLength(200)]);              
} else {                
    this.businessFormGroup.controls['description'].setValidators([Validators.maxLength(200)]);               
}

请务必记住，使用此方法将覆盖现有的验证器，因此您将需要包括/需要用于重置控件的所有验证器.

It is important to keep in mind that by using this method you will overwrite your existing validators so you will need to include all the validators you need/want for the control that you are resetting.

这篇关于Angular-动态添加/删除验证器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！