As a WordPress developer that creates highly customized products for my clients, I found myself running into the same problem over and over again when attempting to create PHP scripts within the WordPress framework. I love using the built-in functionality of WordPress, but I kept running into the same error messages over and over: “call to undefined method…” or “failed to open stream.” Then you go on a hunt to find the proper files that you need to include, require, include_once, or require_once, depending upon your needs. Once you find the right file, usually some PHP document in the wp-includes folder, for example, you have to include/require it at the beginning of your script?— often only to find another “call to undefined method…” To save time and let you start creating code now , not after hours (or days) of Googling a solution, I created a simple script with which I start all my custom files. It handles all the proper files I need for 99% of my development.

Caveat

I only recommend using this while you are developing your plugin, themes, or scripts and then later, before going to production, finding which files you actually need. I do not recommend you keep this script running all the time as it makes unnecessary calls for files you likely don’t need. I’ll walk you through this script so that you can see what I’m doing and why. This can also work as a reference tool for you later.

Forget ABSPATH?— Make Your Own Path

I like to always have the ABSPATH defined, but it’s hit or miss with some scripts and WordPress installs. I used to use the simple if test to check whether or not the ABSPATH is defined, but that doesn’t always work out either: [sourcecode language=”php”] /* NOTE: This is what I do NOT do any more */ // Define the ABSPATH if ( !defined(‘ABSPATH’) ) } define(‘ABSPATH’, dirname(___FILE___) . ‘/’); }[/sourcecode] Instead, I create my own path to my WordPress install that is far more stable: [sourcecode language=”php”] $location = $_SERVER[‘DOCUMENT_ROOT’]; include ($location . ‘/wp-config.php’); include ($location . ‘/wp-load.php’); include ($location . ‘/wp-includes/pluggable.php’); [/sourcecode] This assumes your WordPress install is in the root of your website i.e. www.yoursite.com If that’s not the case, simply add the string to your $location variable like this: [sourcecode language=”php”] $location = $_SERVER[‘DOCUMENT_ROOT’] . ‘/your-wp-install’; [/sourcecode]

The Big Three

In my experience, there are three files that cause all my problems when it comes to setting up my scripts. I call these my “Big Three” because once I include or require them, most of my problems go away when it comes to the “call to undefined method” errors. They are:

1. wp-config.php
2. pluggable.php
3. wp-load.php

Once you have these, you’ll find most of your errors go away. [sourcecode language=”php”] // Get the Big Three include (ABSPATH . ‘wp-config.php’); include (ABSPATH . ‘wp-load.php’); include (ABSPATH . ‘wp-includes/pluggable.php’); [/sourcecode]

Global $wpdb

Another helpful thing to do is to make sure that your $wpdb is a global variable. This allows any functions you create to have access to the WordPress database query features. This can be a huge time saver. Because you included the wp-config.php and wp-db.php files, you shouldn’t have any problems getting $wpdb to work properly, but I still like to run an if test to check first: [sourcecode language=”php”] // Get the Big Four global $wpdb; if( !isset($wpdb) ) { include ($location . ‘/wp-config.php’); include ($location . ‘wp-includes/wp-db.php’); }[/sourcecode]

Test the Script

If you’re starting with a fresh install of WordPress, you only have one admin user. So, there’s no point in trying to connect to the WordPress database and query users. I built this simple test to see if we are connecting properly. If so, you’ll see your name and email address registered with WordPress in a table: [sourcecode language=”php”] /* Test above include statements are working by listing all the admins and their email addresses in a table. */ // Start Test $args = array( //set up the query to only get admins ‘role’ => ‘Administrator’, ‘fields’ => ‘a(chǎn)ll_with_meta’ ); $query = get_users( $args ); //use the get_users call // Set up the table echo ‘’; // For each of the admins, make a table row foreach ($query as $query) { echo ‘’; } //End foreach echo ‘

Nice Name	Email
’ . $query->user_nicename . ‘	user_email . ‘”>’ . $query->user_email . ‘

’; // close the table tag // End Test – comment out or delete from here to the above “Start Test” [/sourcecode] If the test works and you see your name and email address, just delete our comment out the test script and start coding away! You can drop this PHP file anywhere within the WordPress folders and it will work. So, for initial testing and programming, this script can save you tons of time otherwise spent troubleshooting basic technical problems. Again, you may want to do some detail work once your functions work properly and only include the absolutely necessary files. If you don’t need to include the wp-config.php file, for example, don’t! Just comment out the code, line by line, and see if it works properly. Keep what you need, lose the rest. Hopefully this will save you a bunch of time and let you focus on coding, rather than basic mapping of required files for WordPress development. Here’s the complete script for easy reference. Just copy, save the file wherever needed, and have some fun getting work done: [sourcecode language=”php”] ‘Administrator’, ‘fields’ => ‘a(chǎn)ll_with_meta’ ); $query = get_users( $args ); //use the get_users call // Set up the table echo ‘’; // For each of the admins, make a table row foreach ($query as $query) { echo ‘’; } //End foreach echo ‘

Nice Name	Email
’ . $query->user_nicename . ‘	user_email . ‘”>’ . $query->user_email . ‘

’; // close the table tag // End Test – comment out or delete from here to the above “Start Test” ?> [/sourcecode] Would you like to delve a little deeper into PHP? Check out our partner site, PHPMaster.com.

Frequently Asked Questions (FAQs) about WordPress Include/Require Script

What is the difference between include and require in WordPress?

In WordPress, both include and require are used to include a file into another PHP script. The main difference lies in how they handle failure. If the file is not found, include will emit a warning but allow the script to continue, while require will cause a fatal error and halt the script. Therefore, use require when the file is necessary for the application to run, and use include when the file is not mandatory.

How can I use the include/require script for security in WordPress?

The include/require script can be used to enhance the security of your WordPress site by including security-related PHP files. For instance, you can include a file that contains functions for sanitizing user input, checking user permissions, or preventing SQL injection attacks. Always ensure that the path to the included file is correct and secure to prevent file inclusion vulnerabilities.

Why is my wpdb not working or showing anything in posts?

There could be several reasons why wpdb is not working as expected. It could be due to a syntax error, incorrect database credentials, or a problem with the database server. Make sure that you have included the wp-load.php file at the beginning of your script to use the wpdb class. Also, check your SQL query for errors and ensure that it is properly prepared to prevent SQL injection attacks.

What is ABSPATH in WordPress and how can I use it?

ABSPATH is a constant in WordPress that holds the absolute path to the WordPress directory. It is often used in include or require statements to include files from the WordPress directory. To use it, simply prepend ABSPATH to the relative path of the file. For example, require(ABSPATH . ‘wp-config.php’); will include the wp-config.php file.

How can I properly add JavaScript to WordPress?

To properly add JavaScript to WordPress, you should use the wp_enqueue_script function. This function allows you to include a JavaScript file in the WordPress header or footer, specify dependencies, and control the versioning of the file. Always use wp_enqueue_script in the functions.php file or a plugin, and not directly in the header.php or footer.php files.

Why is my wpdb not loading?

If your wpdb is not loading, it could be due to a missing global declaration in your function. The wpdb class is a global variable in WordPress, so you need to declare it as global before using it in a function. For example, global $wpdb; at the beginning of your function should solve the problem.

How can I use the include/require script to include a CSS file in WordPress?

To include a CSS file in WordPress, you should use the wp_enqueue_style function, not the include or require script. The wp_enqueue_style function allows you to include a CSS file in the WordPress header, specify dependencies, and control the versioning of the file. Always use wp_enqueue_style in the functions.php file or a plugin, and not directly in the header.php file.

Can I use the include/require script to include a PHP file in a WordPress post?

No, you cannot use the include or require script to include a PHP file in a WordPress post. WordPress posts do not support PHP code for security reasons. If you need to include a PHP file in a post, you should create a shortcode that includes the file and use the shortcode in the post.

How can I use the include/require script to include a file from a plugin in WordPress?

To include a file from a plugin in WordPress, you can use the plugin_dir_path function in combination with the include or require script. The plugin_dir_path function returns the absolute path to the directory of a plugin. For example, include(plugin_dir_path(FILE) . ‘myfile.php’); will include the myfile.php file from the same directory as the current file.

Can I use the include/require script to include a file from a theme in WordPress?

To include a file from a theme in WordPress, you can use the get_template_directory function in combination with the include or require script. The get_template_directory function returns the absolute path to the directory of the current theme. For example, include(get_template_directory() . ‘/myfile.php’); will include the myfile.php file from the current theme directory.

The above is the detailed content of The Ultimate Include/Require Script for WordPress. For more information, please follow other related articles on the PHP Chinese website!