Composer is a popular tool for managing dependencies in PHP projects. It allows you to install and update packages from various sources, such as Packagist, GitHub, or your own repositories. However, sometimes you may need to modify the code of a package to fix a bug, add a feature, or customize it for your needs. How can you do that without breaking Composer’s functionality or losing your changes when updating the package?

One option is to fork the package’s repository, make your changes there, and then use your fork as the source of the package in your composer.json file. This way, you can keep track of your changes and merge them with the upstream updates. However, this approach has some drawbacks:

• You need to maintain your own fork of the package, which can be time-consuming and tedious.
• You need to update your composer.json file every time you change the source of the package, which can be error-prone and inconvenient.
• You may not want to share your changes publicly or deal with pull requests and issues on GitHub.

Another option is to use Composer’s patch feature, which allows you to apply your own patches to any package after installing or updating it. A patch is a file that contains the differences between two versions of a file or a set of files. You can create patches using tools like Git or diff. With Composer’s patch feature, you can specify a list of patches for each package in your composer.json file, and Composer will automatically apply them after downloading the package. This way, you can keep your changes in your own project and avoid modifying the vendor directory directly. This approach has some advantages:

• You don’t need to maintain a fork of the package or change its source in your composer.json file.
• You can easily revert or update your patches without affecting the original package code.
• You can keep your patches private or share them selectively with others.

To use Composer’s patch feature, you need to install the cweagans/composer-patches plugin, which adds support for patching packages to Composer. To install it, run:

composer require cweagans/composer-patches

Then, in your composer.json file, add a section called “patches” under “extra”, where you can list the patches for each package. For example:

{
  "extra": {
    "patches": {
      "vendor/package": {
        "Patch description": "path/to/patch/file.patch"
      }
    }
  }
}

You can also use URLs or local paths as the source of the patch files. For example:

{
  "extra": {
    "patches": {
      "vendor/package": {
        "Patch description": "https://example.com/patch/file.patch"
      }
    }
  }
}

or

{
  "extra": {
    "patches": {
      "vendor/package": {
        "Patch description": "../patches/file.patch"
      }
    }
  }
}

You can also use wildcards to apply patches to multiple packages that match a pattern. For example:

{
  "extra": {
    "patches": {
      "vendor/*": {
        "Patch description": "path/to/patch/file.patch"
      }
    }
  }
}

This will apply the same patch to all packages under the vendor namespace.

To apply the patches, run:

composer install

or

composer update

Composer will download the packages and then apply the patches according to your composer.json file. You will see a message like this:

  - Applying patches for vendor/package
    path/to/patch/file.patch (Patch description)

If there are any errors or conflicts when applying the patches, Composer will notify you and ask you how to proceed. You can choose to skip the patch, retry applying it, or abort the whole process.

To revert the patches, run:

composer install --no-patches

or

composer update --no-patches

Composer will reinstall or update the packages without applying any patches.

To learn more about Composer’s patch feature, check out the documentation of the cweagans/composer-patches plugin: https://github.com/cweagans/composer-patches

I hope this article was helpful and informative. If you have any questions or feedback, feel free to leave a comment below.