Angular - 文件输入字段上的更改检测仅工作一次

Question

The problem is that I have a file input field that takes only one file at a time, I need it to be like this.

If I try to upload one file, everything is fine. But if I need to upload more files it seems like the "change" handler method is not being called unless I reload the page, which is not what anyone would want.

The HTML looks like this:

<div class="col-xs-7">
    <button
      class="btn btn-primary"
      [disabled]="isLoadingModal"
      (click)="activityFileInput.click()">
    archivo</button> {{ newActivity.fileName }}
    <input
      type="file"
      id="activity-file-input"
      [disabled]="isLoadingModal"
      (change)="selectFile(activityFileInput.files[0])"
      #activityFileInput
      hidden>
  </div>

The function in the component is:

selectFile(file: File): void {
    console.log('Hello');

    if(file == undefined)
      return;

    this.newActivity.fileName = file.name;
    this.newActivity.file = file;
}

On the first file upload the "Hello" shows, no problem. But the method doesn't seem to be called more than once. How can this be solved?

Answer 1

Set the value of the input to null in the onclick event...

<input
  type="file"
  id="activity-file-input"
  onclick="this.value = null"
  [disabled]="isLoadingModal"
  (change)="selectFile(activityFileInput.files[0])"
  #activityFileInput
  hidden>

Answer 2

it happens only when you try to upload the same file/image. When (change) sees the same event, it doesn't trigger the given method. To fix it add (click)="$event.taget.value=null" in your input tag