WordPress Using wp_config.php variables in other PHP files to Connect to DB

Question

I have a simple php file that is connect to the wordpress DB and any thing that want works fine. But I want to use the value from wp_config.php file from wordpress to connect my php file to DB. I tried this but it's not working

   <?php

require_once('wp-config.php');
$conn = new mysqli(DB_HOST, DB_USER, DB_PASSWORD , DB_NAME);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

And this is my default PHP file that works. This file is in a directory inside the WordPress project that I use inside the other template for a custom search.

// Create connection
$conn = new mysqli($servername, $username, $password , $database);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

Note: I change the important Data! Do you have a solution for this?

Answer 1

You really should be using PDO to connect, but other than that, perhaps try using constant("variable") instead of trying to use the variables directly:

<?php
require_once('wp-config.php');
$conn = new mysqli(constant("DB_HOST"), constant("DB_USER"), constant("DB_PASSWORD"), constant("DB_NAME"));
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

Answer 2

The same code works fine for me.

Check the wp-config.php path and try to echo the constants and check you have included the correct file before passing to mysqli

 echo DB_HOST;
 echo DB_USER;
 echo DB_PASSWORD;
 echo DB_NAME;

or you can use wp-load.php include('/path/wp-load.php');

include_once ('/path/wp-load.php');
$conn = new mysqli(DB_HOST, DB_USER, DB_PASSWORD , DB_NAME);
// Check connection
if ($conn->connect_error)
   die("Connection failed: " . $conn->connect_error);

Answer 3

Using the defines the user sets in wp-config:

mysql_connect(DB_HOST, DB_USER, DB_PASSWORD);

Since your script is outside the Wordpress environment, try this:

require_once(path/to/wp-config.php');
mysql_connect(DB_HOST, DB_USER, DB_PASSWORD);

Answer 4

Since you want to connect WP DB in other external application or in a template to get data from WP DB you can include wordpress file directly in your file. using wp-blog-header.php will load complete wordpress into your current template and then you can use make use of it.

include_once $_SERVER['DOCUMENT_ROOT'].'/YOUR_WP_DIR/wp-blog-header.php';
global $wpdb; // wordpress database object
print_r($wpdb);

Content of wp-blog-header.php :

/**
 * Loads the WordPress environment and template.
 *
 * @package WordPress
 */

if ( !isset($wp_did_header) ) {

    $wp_did_header = true;

    // Load the WordPress library.
    require_once( dirname(__FILE__) . '/wp-load.php' );

    // Set up the WordPress query.
    wp();

    // Load the theme template.
    require_once( ABSPATH . WPINC . '/template-loader.php' );

}