save and display for files in user profile in Moodle - php

Question

I'm trying to create a moodle profile field plugin for file upload.
my edit_field_add in field.class is:
function edit_field_add(&$mform) {
$maxlength = 1024*1024;
$fieldtype = $this->field->param2;
/// Create the form field
$mform->addElement('filepicker', $this->inputname, format_string($this->field->name), null,
array('maxbytes' => $maxlength, 'accepted_types' => $fieldtype));
$mform->setType($this->inputname,PARAM_FILE);
}
This shows and saves file correctly but
Saves a number in data field of plugin (e.g. 766686554)
How can I find the URL to the uploaded file to make a link to it by display_data in 'field.class` ?
EDIT
I'm saving the file by this:
function edit_save_data_preprocess($data, &$datarecord) {
$draftitemid=file_get_submitted_draft_itemid($this->inputname);
if (empty($entry->id)) {
$entry = new stdClass;
$entry->id = 0;
}
$context = context_user::instance($this->userid);
file_save_draft_area_files($draftitemid, $context->id, 'profile_field_fileupload', $this->inputname,$entry->id);
return $draftitemid;
}
But draft still exists and I cant find how to retrieve saved file!

Answer 1

Assuming you have saved the file after the form has been posted -http://docs.moodle.org/dev/Using_the_File_API_in_Moodle_forms#filepicker
Then you can use the File API to retrieve the file(s) - http://docs.moodle.org/dev/File_API#Serving_files_to_users
eg to display links to all files for the plugin:
$out = array();
$fs = get_file_storage();
$files = $fs->get_area_files($contextid, $pluginname, $pluginfolder);
foreach ($files as $file) {
$filename = $file->get_filename();
$url = moodle_url::make_file_url('/pluginfile.php', array(
$file->get_contextid(),
$pluginname,
$pluginfolder,
$file->get_itemid(),
$file->get_filepath(), $filename)
);
$out[] = html_writer::link($url, $filename);
}
$br = html_writer::empty_tag('br');
echo implode($br, $out);