在 angular 表单中为文件上传设置自定义验证未按预期工作

Question

I want to implement upload pdf file validation. If uploaded pdf file is password protected then it should not be allowed. I am using angular typescript.

Below is My Custom Validation Function

export function pdfFileValidator(file: File,fileExtension:string): ValidatorFn {
    return (control: AbstractControl): { [key: string]: any } | null => {
    var res = false;
    if(fileExtension.toLowerCase() === 'pdf'){
        pdfjsLib.GlobalWorkerOptions.workerSrc = 'pdf.worker.js'
        var url = URL.createObjectURL(file);
        const loadingTask = pdfjsLib.getDocument(url);
        loadingTask.promise.then(function(pdf) {console.error(pdf)})
        .catch((e:PasswordException) => {
            console.error("File is Password Protected")
            res = true;
        }).finally( ()  =>{
            return {
                'EncryptedFileViolated': res,
            }; 
        });
    }
    console.error("response =",res)
    return null;
    };
}

Below is my set Validation function

  setFileValidators(fileSize: number, fileExtension: string,file:File) {
    this.form.get('file')?.setValidators([FileSizeValidator(fileSize, this.maxSizeAllowedInMB),
    FileExtensionValidator(fileExtension, ['pdf','jpg','png']),pdfFileValidator(file,fileExtension)]);
    this.form.get('file')!.updateValueAndValidity()
    console.error(this.form);
  }

How It is working now

these two lines executed earlier without waiting for the complete execution of the pdfFileValidator function

  this.form.get('file')!.updateValueAndValidity()
  console.error(this.form);

And Form shows status = valid

I want this.form.get('file')?.setValidators() should wait for completion of pdfFileValidator() function and after that execute updateValueAndValidity() function.

How we can implement this?

Answer 1

You pdfJs library function is taking time and you have set synchronous validation with setValidators function and due to this its not working as you want.

You have to set asynchronous validators withsetasyncvalidators