Using wp config to connect to a DB from a plugin

Question

Im using the following to access tables information from my Wordpress DB

    require_once(ABSPATH . 'wp-config.php');
$conn = mysqli_connect(DB_HOST, DB_USER, DB_PASSWORD);
mysqli_select_db($conn, DB_NAME);

It works fine I'm able to connect and display the information. The trouble is when I try to do the same thing from a plugin within the Dashboard under tools, I get the following message:

Notice: Use of undefined constant ABSPATH - assumed 'ABSPATH' in C:\xampp\htdocs\wordpressexpensereport\wp-content\plugins\editdb\connection.php on line 2

Warning: require_once(ABSPATHwp-config.php): failed to open stream: No such file or directory in C:\xampp\htdocs\wordpressexpensereport\wp-content\plugins\editdb\connection.php on line 2

Fatal error: require_once(): Failed opening required 'ABSPATHwp-config.php' (include_path='.;C:\xampp\php\PEAR') in C:\xampp\htdocs\wordpressexpensereport\wp-content\plugins\editdb\connection.php on line 2

I have checked my wp config and I do have the following

    /** Absolute path to the WordPress directory. */
if ( !defined('ABSPATH') )
    define('ABSPATH', dirname(__FILE__) . '/');

/** Sets up WordPress vars and included files. */
require_once(ABSPATH . 'wp-settings.php');

Is there something I am missing with my implementation?

Thanks

Answer 1

I'm guessing this is a custom "plugin" where you are wanting to run a file externally that connects to the WordPress database, not really as a standard plugin which loads within WordPress environment, as in that case as @belinus says you can just use $wpdb class.

Anyway, since ABSPATH is defined IN wp-config.php, you can't use ABSPATH to find and load wp-config.php - because it hasn't loaded and thus isn't defined yet. That's the flawed logic... hence the errors you are getting.

If you know for certain that wp-config.php is in a directory above where the "plugin" file is, you can do something like this:

function find_require($file,$folder=null) {
    if ($folder === null) {$folder = dirname(__FILE__);}
    $path = $folder.'/'.$file;
    if (file_exists($path)) {require($path); return $folder;}
    else {
        $upfolder = find_require($file,dirname($folder));
        if ($upfolder != '') {return $upfolder;}
    }
}
$configpath = find_require('wp-config.php');

This will recursively search for wp-config.php above the plugin file directory and load it when it does. (Again this assumes the wp-config.php is located in a directory above the plugin file.)

Answer 2

You are probably just missing the slash in the require_once. Change it to:

require_once(ABSPATH . '/wp-settings.php');