.. _ci47-rest-part1:

Getting Started with REST APIs ##############################

.. contents:: :local: :depth: 2

This tutorial walks you through building a simple RESTful API to manage books in CodeIgniter 4. You'll learn to set up a project, configure a database, and create API endpoints, and what makes an API RESTful.

This tutorial will primarily focus on:

Auto-routing (Improved)
Creating JSON API endpoints
Using the API ResponseTrait for consistent responses
Basic database operations with Models

.. tip::

While we cover the basics of CodeIgniter, it is assumed that you have at least progressed through the :doc:`First App tutorial <../first-app/index>`.

.. toctree:: :hidden: :titlesonly:

first-endpoint
database-setup
controller
conclusion

Getting Up and Running

Installing CodeIgniter

.. code-block:: console

composer create-project codeigniter4/appstarter books-api
cd books-api
php spark serve

Open your browser to http://localhost:8080 and you should see the CodeIgniter welcome page.

.. note::

Keep the server running in one terminal. If you prefer, you can stop it anytime with :kbd:`Ctrl+C` and start again with ``php spark serve``.

Setting Development Mode

Copy the environment file and enable development settings:

.. code-block:: console

cp env .env

Open .env and make sure this line is uncommented:

.. code-block:: ini

CI_ENVIRONMENT = development

You can also use the spark env command to set the environment:

.. code-block:: console

php spark env development

Configure SQLite

We'll use a single-file SQLite database under writable/ so there's no external setup.

Open .env and uncomment the database section, then set:

.. code-block:: ini

database.default.DBDriver = SQLite3
database.default.database = database.db
database.default.DBPrefix =
database.default.username =
database.default.password =
database.default.hostname =
database.default.port     =

CodeIgniter will automatically create the SQLite database file if it doesn't exist, but you need to ensure that the writable/ directory is writable by the web server.

.. warning::

On some systems you might need to adjust group/owner or use ``chmod 666`` temporarily during development. Never ship world-writable permissions to production.

At this point, you have a working CodeIgniter4 project with SQLite configured.

The app starts with php spark serve
CI_ENVIRONMENT is set to development in .env
writable/database.db exists and is writable

What's Next

In the next section, we'll enable auto-routing and create a simple JSON endpoint (/api/pings) to see how HTTP verbs map to controller methods in CodeIgniter.