Possible to upload to S3 when using Assets field in channel form as file input?

Question

Within a channel form, I'm using an Assets field that points to an S3 external source. I'm using the <input type="file" name="assets_field_name"> method (from http://docs.pixelandtonic.com/assets/templating/channel_form.html). When I submit the form, the entry is created, but the image is not uploaded. If I use the {field:assets_field_name} method, the image is uploaded, however I need to maintain my form's visual style, so I can't use this method.

The S3 credentials are valid, and I'm able to upload and manage photos from the backend.

Using the <input type="file" name="assets_field_name"> method, is it possible to upload directly to S3 from a channel form?

Answer 1

Yes, but you need to add the hidden field with the remote source's ID as the value attribute.

<input type="hidden" name="assets_field_name_source" value="1">