Deactivating a plugin at activation time

3-minute read

While developing the Route Pages plugin I’ve ran into the need to make sure that WP Router plugin is installed and activated in the WordPress installation and got a little confused while trying to sort out a way to

  1. avoid plugin activation
  2. give the user information about what’s happening

A first, non working, version

My first attempt was code like this

/**
 * Activate the plugin
 */
public static function activate()
{
    // check for WP Router plugin to be activated
    $isWPRouterInactive = is_plugin_inactive('WP-Router/wp-router.php');

    if ($isWPRouterInactive) {

        deactivate_plugins(plugin_basename(__FILE__));

        add_action('admin_notices', function()
            {
                $wpRouterUrl = "http://wordpress.org/plugins/wp-router/";
                echo sprintf("Route Pages requires <a href=\"%s\">WP Router plugin</a> to be installed and activated.<br>Install and/or activate it and try again.", $wpRouterUrl));
    }

    // if all ok then...
    $this->goOnWithActivation();
}

Sadly that’s not working at all. I’ve searched the web for a while and could not find much information and have set for an informative wp_die generated screen like the one below [caption id=“attachment_1103” align=“aligncenter” width=“1024”]Die with style Die with style[/caption]

The entry point

The below function, defined in my plugin main file, will take care of checking for the required WP Router plugin and prompt the user with possible actions

/**
 * Activate the plugin
 */
public static function activate()
{
    // check for WP Router plugin to be installed and activated
    $isWPRouterActive = is_plugin_active('WP-Router/wp-router.php');

    if (!$isWPRouterActive) {

        $installOrActivateLinkFormat = '<a style="float:right;" href="%s">%s WP Router now &#8594;</a>';
        $installOrActivateLink = '';
        $wpRouterPath = self::checkWPRouterInstalled();

        if ($wpRouterPath) {

            // generate an activation URL
            $installOrActivateLink = self::generateWPRouterActivationLink($installOrActivateLinkFormat, $wpRouterPath);

        } else {

            // generate an installation URL
            $installOrActivateLink = self::generateWPRouterInstallationLink($installOrActivateLinkFormat);

        }

        // do not activate the plugin
        deactivate_plugins(plugin_basename(__FILE__));

        // display the die message
        $dieMessage = self::generateWpDieMessage($installOrActivateLink);

        wp_die($dieMessage);
    }

    // requirements are ok, go on
    ...
}

thanks to PHPStorm magical refactoring abilities I’ve moved the code into separate functions and will walk them here for my future memory.

Checking if a plugin is installed

WordPress does not pack a is_plugin_installed function so I’ve created one to check if WP Router is installed.

protected static function checkWPRouterInstalled()
{
    // get all the plugins
    $installedPlugins = get_plugins();
    foreach ($installedPlugins as $installedPlugin => $data) {

        // check for the WP Router title
        if ($data['Title'] == 'WP Router') {

            // return the plugin folder/file
            return $installedPlugin;
        }
    }

    return false;
}

That’s probably the trickiest method among all as it requires spoofing the plugin request to pass the nonce check

/**
 * @param $installOrActivateLinkFormat
 * @return string
 */
public static function generateWPRouterActivationLink($installOrActivateLinkFormat, $plugin)
{
    $activateUrl = sprintf(admin_url('plugins.php?action=activate&plugin=%s&plugin_status=all&paged=1&s'), str_replace('/', '%2F', $plugin));

    // change the plugin request to WP Router to pass the nonce check
    $_REQUEST['plugin'] = $plugin;
    $activateUrl = wp_nonce_url($activateUrl, 'activate-plugin_' . $plugin);
    $installOrActivateLink = sprintf($installOrActivateLinkFormat, $activateUrl, 'Activate');

    return $installOrActivateLink;
}

Generating an installation link is easier and does not require any convolute hack

/**
 * @param $installOrActivateLinkFormat
 * @return string
 */
public static function generateWPRouterInstallationLink($installOrActivateLinkFormat)
{
    $slug = 'wp-router';
    $installUrl = admin_url('update.php?action=install-plugin&plugin=' . $slug);
    $installUrl = wp_nonce_url($installUrl, 'install-plugin_' . $slug);
    $installOrActivateLink = sprintf($installOrActivateLinkFormat, $installUrl, 'Install');

    return $installOrActivateLink;
}

Generating an informative die message

Finally I’ve taken some care to generate a wp_die_message that did not left a plugin administrator out of options forcing him/her to make assumptions and hit the dreaded Back button.

/**
 * @param $installOrActivateLink
 * @return string
 */
public static function generateWpDieMessage($installOrActivateLink)
{
    $wpRouterUrl = "http://wordpress.org/plugins/wp-router/";
    $notice = sprintf('<span style="display:block;text-align:center;">Route Pages requires <a href="%s" target="_blank">WP Router plugin</a> to be installed and activated.</span>', $wpRouterUrl);
    $pluginsUrl = admin_url('plugins.php');
    $backToPluginsLink = sprintf('<a href="%s">&#8592; Back to plugins.</a>', $pluginsUrl);
    $dieMessage = sprintf("%s<br><br>%s%s", $notice, $backToPluginsLink, $installOrActivateLink);
    return $dieMessage;
}

And the final result is the one from the image above.