Issue with file uploading in Angular 9 as the uploaded file is not being added to the

I've set up a form group in the HTML of my Angular 9 app that includes an upload feature for files. The file upload works fine when calling the handleFileInput function, as I can confirm from the console log output. However, even though the file gets uploaded successfully, the file property remains NULL when sending the form group to my service. I understand this is because it's initially set as NULL in the constructor, but I'm not sure how to update my code so that the file in the form group reflects the uploaded file. Based on my research, it seems like the form group needs to be defined within the constructor.

export class HelpComponent implements OnInit {

  form: FormGroup;
  srcPage = 'Test';
  fileToUpload: File = null;

  constructor(public fb: FormBuilder, private messageService: MessageService,
              public exportFilesService: ExportFilesService) {

  this.form = this.fb.group({
        summary: new FormControl('', [Validators.required]),
        description: new FormControl('', [Validators.required]),
        isurgent: [false],
        file: this.fileToUpload
      });
   }

  ngOnInit() {
  }

  handleFileInput(files: FileList) {
    this.fileToUpload = files.item(0);
    console.log(this.fileToUpload);
  }

  submitForm() {
      this.messageService.sendSupportRequest(this.form.get('summary').value , 
      this.form.get('description').value, this.form.get('isurgent').value, 
      this.srcPage, this.form.get('file').value);
      }
    }

Answer №1

File uploading in Angular is not explicitly handled by ReactiveForms.

To implement file upload functionality, you can follow these steps: in your html file:

<input type="file" (change)="handleFile($event)" />

And in your ts file:

handleFile(event) {
        const formData: FormData = new FormData();

        const files=event.target.files;
        files.foreach(file=>{
            formData.append(file);
        })

        this.form.patchValue({file:formData});
        this.form.updateValueAndValidity();
    }

Also, make sure to assign the FormBuilder instance fb to your FormGroup form inside the ngOnInit() function.

Your code should look similar to this:

form:FormGroup;

ngOnInit(){
this.form = this.fb.group({
        summary: ['', [Validators.required]],
        description: ['', [Validators.required]],
        isurgent: [false],
        file: ['']
      });
   }
}

Give it a try and see if it works for you!

Answer №2

Remember: According to the information I've come across, it is advisable to relocate the form group declaration from the constructor to OnInit lifecycle hook in your Angular component.

Answer №3

To properly store a reference to a file within your form group, you must instantiate a form control. Here's how you can do it:

this.form = this.fb.group({
        summary: new FormControl('', [Validators.required]),
        description: new FormControl('', [Validators.required]),
        isurgent: [false],
        file: []
      });

When assigning the file, use this method:

handleFileInput(files: FileList) {
    this.form.patchValue({ file: files.item(0) });
  }

It's recommended to create the form group in ngOnInit(), but this alone may not resolve your specific issue.

Currently, your form instantiation includes mixing the form builder (fb) and direct control instantiations. When using fb.group({, values like [] should be used to create a new form control consistently. Update the code for summary and description as follows:

summary: ['', [Validators.required]],
description: ['', [Validators.required]],

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