Potential null value detected in Object.ts(2531) | ImagePicker

After upgrading to Angular 11, I encountered the following error with my code snippet:

const file = (event.target as HTMLInputElement).files[0];
which says Object possibly null

Here is my code in the OnInit class:

imagePreview : string | any;
form: FormGroup | any;

This is the imagepicker function I am using:

onImagePicked(event: Event) {
const file = (event.target as HTMLInputElement).files[0];
this.form.patchValue({
  image: file
});
this.form.get('image').updateValueAndValidity();

const reader = new FileReader();
reader.onload = () => {
  this.imagePreview = reader.result as string;
}
reader.readAsDataURL(file);
}

The error in the main code snippet looks like this

Answer №1

onImagePicked(event: any) {
    const selectedFile = (event.target as HTMLFormElement).files[0];
    this.form.patchValue({
        image: selectedFile
    });
    this.form.get('image').updateValueAndValidity();
    const reader = new FileReader();
    reader.onload = () => {
        this.imagePreview = reader.result as string;
    }
    reader.readAsDataURL(selectedFile);
}

This solution did the trick for me :)

Answer №2

Consider utilizing an if statement to verify the existence of files.

onImagePicked(event: React.FormEvent) { //try using an if condition in case React.FormEvent is not functioning as expected
   if(event.target.files){
    const selectedFile = (event.target as HTMLInputElement).files[0];
    this.form.patchValue({
      image: selectedFile
    });
  ...
}

Answer №3

When dealing with HTMLInputElement, the expected files type is FileList or null. Therefore, it was assumed that File would also be null based on this premise. The corresponding code snippet is as follows:

onSelectFile(event: Event) {
  const file = (event.target as HTMLInputElement).files?.[0];
  this.form.patchValue({
    image: file
  });
  this.form.get('image')?.updateValueAndValidity();
  const reader = new FileReader();
  reader.onload = () => {
    this.imagePreview = reader.result;
  };
  reader.readAsDataURL(file);
}

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