Validate Gravity Forms Empty File Uploads

README.md

iOS has a bug with input[type="file"] where a delay in submitting a form from an HTTPS URL after attaching a file will result in an empty zero byte file being sent to the server. To reproduce the issue, create a form with an input[type="file"] on an HTTPS URL, attach a file, then wait 90 seconds before submitting.

If you develop WordPress sites that use Gravity Forms, the above validation filter present an error message when empty, zero-byte files are uploaded.

gravity-forms-tweaks.php

<?php

add_filter(
	'gform_field_validation',
	function( $result, $value, $form, $field ) {
		if ( $field->type === 'fileupload' ) {
			if ( isset( $_FILES[ 'input_' . $field->id ] ) && $_FILES[ 'input_' . $field->id ]['size'] < 1 ) {
				$result["is_valid"] = false;
				$result["message"] = "There was a problem uploading your resume. If you are using an iOS device, you must submit this form within 30 seconds of attaching your resume. Please click or tap the red x above, add your resume and resubmit. We apologize for the inconvenience.";
			}
		}
		return $result;
	},
	10,
	4
);