Is it possible to subscribe to changes in an input type file using FormControl?

Question

Is it possible to subscribe to changes in an input type file using FormControl?

After subscribing to the FormControl.valueChanges() triggered by selecting a file on an input, I noticed that the value emitted does not include the full file path. Is there a way to access this information through subscription, or do we need to retrieve it directly from the element using @ViewChild? The HTML setup is as follows:

<input #file name='file' id='file' type='file' [formControl]='loadButton'/>

The subscription code looks like this:

this.loadButton.valueChanges
    .pipe(untilDestroyed(this))
    .subscribe(path => {
      console.dir(path);
    });
}

After selecting a file, the output in the console is:

C:\fakepath\test.png

javascript angular typescript rxjs html5-filesystem

Answer 1

Answer №1

For my latest project, I consolidated all the necessary functionality into a single component. Here's how I approached it:

import { Component, EventEmitter, Output } from '@angular/core';
@Component({
  selector: 'app-image-uploader',
  template: '<input type="file" (change)="onUploadFileChanged($event)" />',
})
export class ImageUploaderComponent implements OnInit {
    @Output() uploadStatusChange = new EventEmitter<any>();
    onUploadFileChanged(event) {
        this.targetElement = event.target;
        if (event.target.files && event.target.files[0]) {
            component.uploadStatusChange.emit('ready');
        }
    }

}

Once a file is selected, the component informs the parent component that it is ready, allowing you to then set the form control to true. The HTML structure of the parent component would look something like this, where in this example $event contains the string 'ready':

<app-image-uploader (uploadStatusChange)="yourFunction($event)"></app-image-uploader>

If dealing with images, you can also utilize FileReader to display them before uploading.

Answer 2

For my latest project, I consolidated all the necessary functionality into a single component. Here's how I approached it:

import { Component, EventEmitter, Output } from '@angular/core';
@Component({
  selector: 'app-image-uploader',
  template: '<input type="file" (change)="onUploadFileChanged($event)" />',
})
export class ImageUploaderComponent implements OnInit {
    @Output() uploadStatusChange = new EventEmitter<any>();
    onUploadFileChanged(event) {
        this.targetElement = event.target;
        if (event.target.files && event.target.files[0]) {
            component.uploadStatusChange.emit('ready');
        }
    }

}

Once a file is selected, the component informs the parent component that it is ready, allowing you to then set the form control to true. The HTML structure of the parent component would look something like this, where in this example $event contains the string 'ready':

<app-image-uploader (uploadStatusChange)="yourFunction($event)"></app-image-uploader>

If dealing with images, you can also utilize FileReader to display them before uploading.

Is it possible to subscribe to changes in an input type file using FormControl?

Answer №1

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