I have in mind two options:

• Code in the class being saved/loaded. The flows for each entity/model are in the same place, so it's easy to just have one file open to see all the functionalities of that class, but this means having more code in a single file.
• Code in a dedicated class (like a factory)
  This makes each file smaller, but spreads flows of a single model into different parts of the repo, also because I'm thinking of having a directory /src/models and another like /src/export (or serialize)

What do you guys think?
What's your preferred way to organize the save and load flows?