'pre_user_query' interfering with user export

Question

I needed to add sortable columns to clients wordpress for custom meta data I created so I used a pre_user_query hook

add_action('pre_user_query', 'user_column_orderby');

function user_column_orderby($user_search) {
    global $wpdb, $current_screen;

    if ( 'users' != $current_screen->id )
        return;

    $vars = $user_search->query_vars;

    if('Kön' == $vars['orderby']) {
        $user_search->query_from .= " INNER JOIN {$wpdb->usermeta} m1 ON {$wpdb->users}.ID=m1.user_id AND (m1.meta_key='gender')";
        $user_search->query_orderby = ' ORDER BY UPPER(m1.meta_value) '. $vars['order'];
    } elseif ('Ålder' == $vars['orderby']) {
        $user_search->query_from .= " INNER JOIN {$wpdb->usermeta} m1 ON {$wpdb->users}.ID=m1.user_id AND (m1.meta_key='age')";
        $user_search->query_orderby = ' ORDER BY UPPER(m1.meta_value) '. $vars['order'];
    } elseif ('Distrikt' == $vars['orderby']) {
        $user_search->query_from .= " INNER JOIN {$wpdb->usermeta} m1 ON {$wpdb->users}.ID=m1.user_id AND (m1.meta_key='district')";
        $user_search->query_orderby = ' ORDER BY UPPER(m1.meta_value) '. $vars['order'];
    } elseif ('Kategori' == $vars['orderby']) {
        $user_search->query_from .= " INNER JOIN {$wpdb->usermeta} m1 ON {$wpdb->users}.ID=m1.user_id AND (m1.meta_key='category')";
        $user_search->query_orderby = ' ORDER BY UPPER(m1.meta_value) '. $vars['order'];
    }
}

This works fine if you're on the user screen. But I also added a export to csv button, which calls my export-csv.php file that looks like this:

<?php
$location = $_SERVER['DOCUMENT_ROOT'];
include ($location . '/wp-load.php');

if (current_user_can('manage_options')) {
    header("Content-type: application/force-download");
    header('Content-Disposition: inline; filename="users'.date('YmdHis').'.csv"');

    // WP_User_Query arguments
    $args = array (
        'order'          => 'ASC',
        'orderby'        => 'display_name',
        'fields'         => 'all',
    );

    // The User Query
    $blogusers = get_users( 'orderby=nicename&order=ASC' );
    // Array of WP_User objects.
    foreach ( $blogusers as $user ) {
        //echo '<span>' . esc_html( $user->user_email ) . '</span>';
        print_r($user);
    }
}

Now, the problem I'm having is that my .csv file has a notice:

Notice: Trying to get property of non-object in .../wp-content/themes/mytheme/admin/users_additionals.php on line 133

Which points to the line:

if ( 'users' != $current_screen->id )

in my first code. This happens because I've hooked to the pre_user_query hook, and I'm querying users in my file. Is there a way to suppress this notice (without going to wp-config.php and removing the debug code - this is not the solution, just masking the problem)?

Answer 1

'users' != $current_screen->id in your file $current_screen is not set therefore, you are getting warning.

You can pass custom var in your user query and check before running your code.

$blogusers = get_users( 'orderby=nicename&order=ASC&my_filter=1' ); 

Here we are passing my_filter=1 then later we can check in pre_user_query

global $wpdb, $current_screen;

$vars = $user_search->query_vars;

if (isset($current_screen->id) && 'users' != $current_screen->id) {
    return;
} else if (empty($vars['myfilter'])) {
    return;
}

However, loading WordPress in a external file is not a good thing. Instead of external file you can wrap the whole code in a function and hook it on some action where headers are not sent.

Example:

Create a form instead of link e.g.

<form action="" method="POST">
    <input type="hidden" name="myprefix_export_csv" value="1" />
    <input type="submit" value="download" />
</form>

Then check if your custom key is set, if it is then export CSV with your current code.

add_action('init', 'export_csv'); //you can use admin_init as well
function export_csv() {
    if (!empty($_POST['myprefix_export_csv'])) {

        //Send headers
        //Query users
        //print data

        exit();
    }
}

You can also set nonce in form if you think other users can tweak it.