如何仅在 Angular 中验证 11 位数字的输入字段？

Question

I have an Input field in my angular template-driven form. I want to configure that fields so that it can only take an 11bits number like 01001111100

<input
    class="form-control"
    id="bitsValue"  
    [placeholder]="field.templateOptions.placeholder"
    pattern="[0-1]{1}"
    [(ngModel)]="ABC"
>

How can I do that?

Answer 1

If you were to use reactive forms, create you form for example:

this.myForm = this._sb.fb.group(
{
    bitsValue: this._sb.fb.control('', [Validators.required, YourValidatorClass.elevenBitsOnly])        
};
    
    
export class YourValidatorClass {
        
static elevenBitsOnly(control: AbstractControl): ValidationErrors | null {
   const value = control.value;
   //... validate your value meets your 11 bit requirement
         return { bitValueReq: 'You must provide value as 11 bits number' };
   //... if it doesn't meet the requirement return null
         return null;
   }
}

Then in your html template:

<div [formGroup]="myForm">
 <mat-form-field>       
        <input matInput type="text" formControlName="bitsValue"  />
        <mat-error *ngIf="myForm.hasError('bitValueReq'))"> {{ getErrorMessage(myForm.get('bitsValue')) }}</mat-error>
    </mat-form-field>
</div>

....component.ts file:

getErrorMessage(control: AbstractControl): string{
  const error = control.getError('bitValueReq');
    if(error){  ​
  ​  return error['bitValueReq'];
    }
  }