Understanding Composer.json: Difference between require and require-dev

Composer.json is a crucial file in any PHP project that uses Composer as a dependency manager. It lists the packages that the project requires and their dependencies. When using Composer, you may come across the terms require and require-dev. In this article, we'll explore the difference between these two terms and how they affect your project.

What is "require"?

The require keyword is used to specify the packages that are required for your project to function correctly. These packages are installed in the vendor/ directory and are available for use in your project. They are listed in the require section of the composer.json file.

{
    "require": {
        "monolog/monolog": "^2.0",
        "twig/twig": "^2.0"
    }
}

In the example above, the monolog/monolog and twig/twig packages are required for the project.

What is "require-dev"?

The require-dev keyword is used to specify the packages that are required for development purposes only. These packages are not necessary for the project to function correctly but are required for testing, debugging, and other development-related tasks. They are installed in the vendor/ directory, just like packages listed in the require section. They are listed in the require-dev section of the composer.json file.

{
    "require-dev": {
        "phpunit/phpunit": "^6.0",
        "mockery/mockery": "^1.0"
    }
}

In the example above, the phpunit/phpunit and mockery/mockery packages are required for testing purposes.

Why is there a difference?

The difference between require and require-dev is that packages listed in the require section are essential for the project to function correctly, while packages listed in the require-dev section are only required for development tasks. This separation allows for a more streamlined production environment, where only necessary packages are installed, and development packages are excluded.

In conclusion, understanding the difference between require and require-dev is essential when working with Composer. By separating essential packages from development packages, you can ensure that your production environment is streamlined and efficient.