[arthurcolle]

There may be language specific advice, but honestly, you have to go through the entire thing and learn every single line. Most people are okay with just absorbing every little piece they can when they get assigned specific tickets associated with the sprints they are working on, but to really learn the apparatus you have to just learn how the whole thing works.

Of course starting at serializers and then going to routing, etc may seem very bad from a learning-organizational POV, but that's what you have to do to learn the entire application stack.

Is this a web app? Maybe there's better advice depending on the specific piece of software in question but at the end of the day you have to master the paradigm before being able to contribute in a meaningful way.