MinLengthValidator

该指令用于为带有 minlength 属性的控件添加最小长度验证器。该指令会提供 NG_VALIDATORS 多重提供商列表。

A directive that adds minimum length validation to controls marked with the minlength attribute. The directive is provided with the NG_VALIDATORS mult-provider list.

参见

NgModules

选择器

属性

属性说明
@Input()
minlength: string

Tracks changes to the the minimum length bound to this directive.

说明

添加最小长度验证器

Adding a minimum length validator

下面的例子演示了如何为带有 ngModel 绑定的输入框添加最小长度验证器。

The following example shows how to add a minimum length validator to an input attached to an ngModel binding.

<input name="firstName" ngModel minlength="4">
      
      <input name="firstName" ngModel minlength="4">
    

方法

A lifecycle method called when the directive's inputs change. For internal use only.

ngOnChanges(changes: SimpleChanges): void
      
      ngOnChanges(changes: SimpleChanges): void
    
参数
changes SimpleChanges

A object of key/value pairs for the set of changed inputs.

返回值

void

Method that validates whether the value meets a minimum length requirement. Returns the validation result if enabled, otherwise null.

validate(control: AbstractControl): ValidationErrors | null
      
      validate(control: AbstractControl): ValidationErrors | null
    
参数
control AbstractControl
返回值

ValidationErrors | null

Registers a callback function to call when the validator inputs change.

registerOnValidatorChange(fn: () => void): void
      
      registerOnValidatorChange(fn: () => void): void
    
参数
fn () => void

The callback function

返回值

void