How to automatically upload a file on form submission

Question

I have created a form with a file attachment field. I have noticed that users will attach a file but sometimes forget to hit the upload button. I would like the form to automatically upload the file when the form submit button is pressed (if a file has been selected to upload).

I have seen a similar answer answer to this at https://drupal.stackexchange.com/a/31453/4471 but that is a slightly different use case then what I am after. I would have thought that submitting a form would automatically upload attached files as default behaviour.

I am working with Drupal 7 by the way.

Thanks.

Answer 1

If a file has been selected in a file upload field, it will be uploaded on form submit regardless of whether the "Upload" button has been pressed.