Encountered an issue while trying to assign a value to the 'value' property on an 'HTMLInputElement' within a reactive form

Question

Encountered an issue while trying to assign a value to the 'value' property on an 'HTMLInputElement' within a reactive form

When I upload a picture as a data record, the image is sent to a server folder and its name is stored in the database.

For this editing form, I retrieve the file name from the server and need to populate <input type="file"> in Angular 6 using reactive forms.

Here's my TypeScript code:

   ngOnInit() {
  this.EditForm=this.fb.group({
  imageName:['',Validators.compose([Validators.required])]
})
this.SetForm(this.dat)
}

  SetForm(dt:data){
   this.EditForm.setValue({imageName:[dt.imageName]});
  }

In the HTML:

<form [formGroup]="EditForm">
    <input type="file" #file formControlName="imageName">
</form>

If you want to see the actual code, here's the link: stackblitz

I've been struggling with this issue for three days now. Please review my code and suggest any changes that could help solve this problem.

javascript angular typescript angular6

Answer 1

Answer №1

To enhance security measures, it is feasible to programmatically assign only an empty string to clear the selection of a file input. Trying to set a value to an input with type file will result in an error message:

ERROR DOMException: Failed to set the 'value' property on 'HTMLInputElement': 
This input element accepts a filename, which may only be programmatically set 
to the empty string.

In order to work around this limitation for modern browsers, one can utilize DataTransfer to adjust the file input value:

Here is the HTML code example (based on stackblitz):

<form [formGroup]="EditForm">
  <input id="my-input" type="file">
</form>

<button (click)="changeFileName()">Change File Name</button>

The corresponding component code:

changeFileName() {
  const dataTransfer = new ClipboardEvent('').clipboardData || new DataTransfer();
  dataTransfer.items.add(new File(['my-file'], 'new-file-name'));
  const inputElement: HTMLInputElement = document.getElementById('my-input') as HTMLInputElement

  inputElement.files = dataTransfer.files;
}

Answer 2

To enhance security measures, it is feasible to programmatically assign only an empty string to clear the selection of a file input. Trying to set a value to an input with type file will result in an error message:

ERROR DOMException: Failed to set the 'value' property on 'HTMLInputElement': 
This input element accepts a filename, which may only be programmatically set 
to the empty string.

In order to work around this limitation for modern browsers, one can utilize DataTransfer to adjust the file input value:

Here is the HTML code example (based on stackblitz):

<form [formGroup]="EditForm">
  <input id="my-input" type="file">
</form>

<button (click)="changeFileName()">Change File Name</button>

The corresponding component code:

changeFileName() {
  const dataTransfer = new ClipboardEvent('').clipboardData || new DataTransfer();
  dataTransfer.items.add(new File(['my-file'], 'new-file-name'));
  const inputElement: HTMLInputElement = document.getElementById('my-input') as HTMLInputElement

  inputElement.files = dataTransfer.files;
}

Answer 3

Answer №2

To update the image, simply remove formControlName="image" and replace it with (change)="onChangeImage()"

Answer 4

To update the image, simply remove formControlName="image" and replace it with (change)="onChangeImage()"

Answer 5

Answer №3

If you want to change the name of an image file, you can follow this method:

In your component.html file, include an event listener for the change event:

<input type="file" (change)="onFileChange($event)" #file formControlName="imageName">

Then, in your component.ts file, implement the logic to create a new file with the updated name:

onFileChange(event) {
  //console.log(event.target.files[0].name)
  var blob = event.target.files[0].slice(0, event.target.files[0].size, 'image/png'); 

  const newFile = new File([blob], this.dat.imageName, {type: 'image/png'})
  //console.log(newFile)
}

This approach ensures that the original file name is retained in the input field, while allowing you to use the newFile in your API requests such as post or put to send the updated file to the server.

Answer 6

If you want to change the name of an image file, you can follow this method:

In your component.html file, include an event listener for the change event:

<input type="file" (change)="onFileChange($event)" #file formControlName="imageName">

Then, in your component.ts file, implement the logic to create a new file with the updated name:

onFileChange(event) {
  //console.log(event.target.files[0].name)
  var blob = event.target.files[0].slice(0, event.target.files[0].size, 'image/png'); 

  const newFile = new File([blob], this.dat.imageName, {type: 'image/png'})
  //console.log(newFile)
}

This approach ensures that the original file name is retained in the input field, while allowing you to use the newFile in your API requests such as post or put to send the updated file to the server.

Answer 7

Answer №4

This solution has been effective for me;

updateFileName() {
  const fileInput: HTMLInputElement = document.getElementById('user-file') as HTMLInputElement
  fileInput.files = null;
}

Answer 8

This solution has been effective for me;

updateFileName() {
  const fileInput: HTMLInputElement = document.getElementById('user-file') as HTMLInputElement
  fileInput.files = null;
}

Answer 9

Answer №5

If you're working with ReactJs, one way to fix the problem is by eliminating the value field in the file input control.

Answer 10

If you're working with ReactJs, one way to fix the problem is by eliminating the value field in the file input control.

Encountered an issue while trying to assign a value to the 'value' property on an 'HTMLInputElement' within a reactive form

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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