Contribution Guidelines

Your Pull Requests (PRs) need to meet our guidelines. If a PR fails to pass these guidelines, it will be declined and you will need to re-submit when you’ve made the changes. This might sound a bit tough, but it is required for us to maintain quality of the code-base.

PHP Style

All code must conform to our Style Guide, which is essentially the Allman indent style, with elaboration on naming and readable operators.

This makes certain that all code is the same format as the existing code and means it will be as readable as possible.

Our Style Guide is similar to PSR-1 and PSR-2, from PHP-FIG, but not necessarily the same or compatible.

Unit Testing

Unit testing is expected for all CodeIgniter components. We use PHPunit, and run unit tests using travis-ci for each PR submitted or changed.

In the CodeIgniter project, there is a tests folder, with a structure that parallels that of system.

The normal practice would be to have a unit test class for each of the classes in system, named appropriately. For instance, the BananaTest class would test the Banana class. There will be occasions when it is more convenient to have separate classes to test different functionality of a single CodeIgniter component.

See the PHPUnit website for more information.

PHPdoc Comments

Source code should be commented using PHPdoc comments blocks. Thie means implementation comments to explain potentially confusing sections of code, and documentation comments before each public or protected class/interface/trait, method and variable.

See the phpDocumentor website for more information.

We use phpDocumentor2 to generate the API documentation for the framework, with configuration details in phpdoc.dist.xml in the project root.


The User Guide is an essential component of the CodeIgniter framework.

Each framework component or group of components needs a corresponding section in the User Guide. Some of the more fundamental components will show up in more than one place.

Change Log

The change-log, in the user guide root, needs to be kept up-to-date. Not all changes will need an entry in it, but new classes, major or BC changes to existing classes, and bug fixes should.

See the CodeIgniter 3 change log for an example.

PHP Compatibility

CodeIgniter4 requires PHP 7.

See the CodeIgniter4-developer-setup repository for tips on setting this up on your system.

That repository also contains tips for configuring your IDE or editor to work better with PHP7 and CodeIgniter4.

Backwards Compatibility

Generally, we aim to maintain backwards compatibility between minor versions of the framework. Any changes that break compatibility need a good reason to do so, and need to be pointed out in the Upgrading guide.

CodeIgniter4 itself represents a significant backwards compatibility break with earlier versions of the framework.


Your PRs need to be mergeable before they will be considered.

We suggest that you synchronize your repository's develop branch with that in the main repository before submitting a PR. You will need to resolve any merge conflicts introduced by changes incorporated since you started working on your contribution.