Magento2: How to create a patch for custom module composer.json?

Question

I want to know that can we create patch for some changes in composer.json of custom module. I am talking about custom module composer not magento composer. Its just like changes but instead of any php file i want to do it in composer.json. Is there a different way? I am using the same old way but its not working.

diff --git a/composer.json b/composer.json

--- a/composer.json

+++ b/composer.json

Answer 1

As an aswer on:

So i want to install an extension but that only works on php 7.3 ( req in composer of module) But my M 2.4.5 works on php 7.4. so i want to change the php version in the req tag of composer.json of extension with patch

You could try those suggestion:

1. The easiest way would be to just install the module without composer in app/code. Copy them from vendor in the right structure. This way you skip any version checks.
2. You could experiment with the --ignore-platform-reqs flag of composer. It will skip the platform requirements checks but I am not sure if you could use it with composer require. You might need to install it first on a platform which does meet the requirements and then do composer install --ignore-platform-reqs to install it from the lock file on the machine which does not meet the requirements.

Good luck!

Answer 2

Looks like you are missing the index in your patch file.

In some cases patch files created by diff -u do not work. You should follow @attila-naghi steps except step 5 (redundant) to get the patch file: https://magento.stackexchange.com/a/315195/39884