Learning PHP for WordPress is part of becoming a competent WordPress developer.
PHP is easy if you have any programming experience. The language is logical and easy to follow.
But you also need to know the PHP standards, libraries, functions, hooks, classes, and methods that Wordpess uses.
The PHP concepts essential to your career are the coding standards, hooks, the loop, database access, and the Code Reference Library.
In this article, you will learn exactly which concepts you must master to be in the top 5% of PHP programmers.
WordPress-specific PHP you must know includes:
- coding standards
- loop content
- theme basics
- The functions you’ll find in the code reference
Why WordPress Uses PHP
PHP has two strengths that make it ideal for web development: content generation (it spits out HTML) and data manipulation (it’s database-aware).
PHP code can be embedded directly into HTML code, making integrating server-side functionality with front-end web development easy.
It has a simple syntax familiar to C or Perl, allowing developers to learn and start building web applications quickly.
A vast community supports PHP and has many libraries and frameworks, making it a versatile language for various web development tasks.
PHP makes it possible to create dynamic web pages, interact with databases, and process user input.
With PHP, you can build custom features and extend the functionality of WordPress.
5 Easy PHP Concepts for WordPress Development
Learn WordPress PHP coding standards, hooks, the loop content output, theme basics, and the Code Reference Library to master your WordPress development career.
1 – Coding Standards
It is essential to follow coding standards when coding in PHP for WordPress.
These standards ensure that your code is clean, readable, and consistent.
Adhering to coding standards maintains your code and minimizes compatibility issues with future WordPress updates.
You will find the WordPress PHP coding standards on the WordPress website.
To summarize WordPress PHP coding standards:
- Put open and closing tags on their own lines.
- Do not use shorthand tags.
- Use double quotes for evaluation and single quotes for strings.
- Use require statements without parentheses.
- Use require rather than include statements.
- Use lowercase and underscores in variable names.
- Use capitals and underscores in constant names.
- Construct dynamic hook names for readability rather than compilation efficiency.
- Use whitespace and tabs for readability.
- Always use braces to enclose statement blocks even when the block is only one line long.
- Do not use shorthand to declare arrays.
- Break multi-line functions into multiple, comma-separated lines
- Use spaces just after opening parentheses and just before closing parentheses
- Use upper and lowercase with underscores to declare classes.
- Surround spread and reference operators with one space on either side.
- Use capitalized words for namespace names
- Use namespaces to modify functions outside of the current namespace.
- Define one class per class file.
- Use tabs to indent multi-line use statements.
- Do not assume default visibility for protected functions; state “protected.”
- use modifiers in order of abstract, readonly and abstract, protected, static, and static protected, final
- Always use parenthesis to instantiate new objects.
- Use elseif not else if
- Compare logical expressions using variables on the right to avoid assignment.
- test for true rather than for false to keep ternary operators easier to read
- Do not suppress errors.
- prefer pre-increment over post-increment operators
- prefer WordPress database functions over direct library calls
- Break up SQL statements into several lines.
- Use datatype placeholders in SQL query strings.
- default function string variable arguments to true
- New WordPress code supports PHP 7 as well as PHP 8
- Only use $args array argument for multi-argument calls
- Do not condense syntax to be clever.
- It is ok to return function results rather than declaring new functions
- Use Perl regex rather than preg_replace_callback syntax
- Never use the extract function
- Do not use backticks or shell_exec calls
2 – Hooks
WordPress hooks allow users to modify and manipulate the functionality of WordPress core, themes, and plugins.
They are a way for you as a developer to customize and extend the behavior of WordPress without directly modifying the core.
How WordPress Uses PHP to Create Actions and Filters
Hooks in WordPress are divided into two categories: actions and filters.
Actions are hooks that allow you to add custom functionality at specific points in WordPress execution.
They are generally used to perform an action or create a new one for others.
Examples of actions include:
- creating a new post
- sending an email notification
- executing a function on page load
Filters allow you to modify specific pieces of data before they are presented in WordPress.
They are used to change the output or behavior of functions and templates.
Filters take a value in, modify it, and then return the adjusted value.
Examples of filters include
- changing the output of a post title
- modifying the content of a post
- manipulating the permalink structure
Plugin and Theme Hooks
Hooks are extensively used in WordPress theme development, plugin development, and site customization.
Some common scenarios where hooks are used the most include:
Hooks allow you to modify theme templates and add custom functionalities without editing the theme files directly.
Hooks play a crucial role in plugin development, allowing developers to inject their custom code at various points in the plugin’s execution.
This enables them to modify existing plugin behavior or add new functionalities.
They can add new sections, modify header and footer, change widgets, and more.
Extending WordPress Core Hooks
Hooks are used to extend the functionality of WordPress core without modifying its codebase.
The hook concept provides a flexible and modular way of customizing and extending WordPress functionality, making it easier for developers to create unique and tailored websites, themes, and plugins.
This allows you to add new features and modify existing behavior per their requirements.
Data Manipulation Hooks
Using filters, hooks can modify and manipulate data before displaying it on a WordPress site.
This includes changing the formatting, modifying content, or filtering specific data based on user-defined conditions.
3 – The Loop
The WordPress PHP loop is a fundamental concept in WordPress development that allows you to display posts or content from your WordPress database on your website.
It is used to iterate over a series of posts and retrieve their data in a structured manner.
The loop exists in WordPress to handle retrieving posts and displaying them on a web page without the need for manual coding for each post.
It helps automate the content display process and ensures consistency throughout the website.
To use the WordPress PHP loop, you will typically write a loop code in your theme’s template files, most commonly in the “index.php” or “single.php” file.
The loop checks if posts are available using the have_posts() function in the most common setup.
If there are posts, the loop will enter the “while” loop and call the the_post() function, which sets up the post data for the current iteration.
Inside the loop, you can use various functions like the_title() and the_excerpt() to display the post title and excerpt respectively.
These functions automatically retrieve the appropriate data for each post.
You can further customize the loop by adding conditions, filters, or additional functions to display specific post types, categories, tags, or custom fields.
The loop is highly versatile and can be extended to meet specific needs.
4 – Theme Basics
The WordPress theme uses everything you’ve learned: coding standards, hooks, and the content loop.
The most important parts of the Theme Handbook are:
Navigation sets up your menus for your users to view the website posts. register_nav_menus allows you to allocate your theme’s navigation blocks.
Thumbnails accept and show the featured image for your post
functions.php allows you to augment the parent styles and add hooks to your theme
templates allow you to construct your theme in logical sections such as the header, footer, and sidebar
5 – WordPress Code Reference
WordPress documents its use of functions, hooks, classes, and methods in the official Code Reference Library.
The reference library is not a tutorial or course.
The material is dry, contains little context, and can be hard to follow.
Use the code reference for verifying your work, not learning the concepts.
But one area where the Code Reference is invaluable is learning what you need to know.
By perusing the contents, you can verify the parts of PHP that WordPress uses to create your own course syllabus.
As you study PHP for WordPress, the Code reference gives you the major topics you need to master to become a competent WordPress developer:
- Dashboard widgets: shortcuts to admin functions
- Database: website data repository
- HTTP API: remote get functions
- Filesystem: file management
- Global Variables: global WordPress information
- Metadata: search engine optimization data
- Options: Plugin preferences
- Plugins: addon functionality
- Quicktags: traditional editor extensions
- REST API: Extend your web application
- Rewrite: change HTTP codes
- Settings: WordPress preferences
- Shortcode: expandable function calls from within content
- Theme Modification: Theme changes
- Transients: intermediate data
- XML-RPC: Post content from remote applications
WordPress PHP Questions and Answers
What is PHP?
PHP is a programming language that is commonly used for web development. It is mainly used to create dynamic web pages and is particularly popular in the WordPress community.
Why should I learn PHP for WordPress?
Learning PHP for WordPress will allow you to customize and extend the functionality of your WordPress website. It will give you more control over the backend of your site and allow you to create unique themes and plugins.
I have no prior coding experience. Can I still learn PHP for WordPress?
Yes, you can learn PHP for WordPress even if you have no prior coding experience. There are many beginner-friendly resources and tutorials available that can help you get started.
Is there a free course available to learn PHP for WordPress?
Many free PHP tutorials and courses are available online that specifically focus on PHP for WordPress. These courses cover the basics of PHP and how to use it in WordPress development.
Are there any paid PHP courses available for WordPress development?
Yes, paid PHP courses are available that specifically focus on WordPress development. These courses typically offer more in-depth content and provide additional resources and support to help you master PHP for WordPress.
How is PHP used in WordPress?
PHP is the programming language used to power WordPress. It is used to create the core functionality of WordPress and allows developers to modify and extend the platform according to their needs.
Can I create my WordPress themes and plugins with PHP?
Yes, you can create your WordPress themes and plugins using PHP. PHP provides the necessary tools and functions to customize the appearance and functionality of WordPress websites.
How can I modify an existing WordPress theme using PHP?
To modify an existing WordPress theme using PHP, you need access to the theme files. You can then change the PHP code to customize the theme according to your requirements.
What are some of the best tutorials to learn PHP for WordPress?
Several websites and online platforms offer tutorials to learn PHP for WordPress. Some popular ones include WordPress.org, W3Schools, and Codecademy.
To become a WordPress developer, you must learn and use the WordPress PHP coding standards.
You will need to learn how WordPress uses PHP for:
- outputting content using the loop
- theme basics
- The functions you’ll find in the code reference