How to add a user to a Users field from front-end form?

Question

Is it possible to update an entry’s Users field from the front-end? If so, how would you go about it?

The situation is this: training events are created and then posted for members to bid on for a limited number of spots. Logged in members review the available events and add their name (would use their ID) to each event of interest. Admins then manually chose a select few from all submissions.

I know I can do this by adding their IDs to a text field in the event section, and then using Split to create an array, but the Users field approach is much more elegant and offers more flexibility.

Answer 1

You would need to do this with a plugin that provides a custom controller, which looks at the post data and modifies the entries’ Users fields accordingly.

The controller action would look something like this:

<?php

$entryIds = craft()->request->getPost('entries');

if ($entryIds && is_array($entryIds))
{
    // Get the current user's ID
    $currentUserId = craft()->userSession->getUser()->id;

    // Fetch the entries
    $criteria = craft()->elements->getCriteria(ElementType::Entry);
    $criteria->id = $entryIds;
    $entries = $criteria->find();

    foreach ($entries as $entry)
    {
        // Update the Users field value with the current user's ID
        $userIds = $entry->myUsersField->ids();
        $userIds[] = $currentUserId;

        $entry->setContentFromPost(array(
            'myUsersField' => $userIds;
        ));

        craft()->entries->saveEntry($entry);
    }
}