Repository and Unit of Work patterns - How to save changes

Question

I\'m struggling to understand the relationship between the Repository and Unit of Work patterns despite this kind of question being asked so many times. Essentially I still don\

Answer 1

I'm actually quite new to this but as nobody wiser has posted:

The code which CRUDs happens in the repositories as you would expect, but when Account.Add (for example) is called, all that happens is that an Account object is added to the list of things to be added later (the change is tracked).

When unitOfWork.Save() is called the repositories are allowed to look through their list of what has changed Or the UoW's list of what has changed (depending on how you choose to implement the pattern) and act appropriately - so in your case there might be a List NewItemsToAdd field that has been tracking what to add based on calls to .Add(). When the UoW says it's OK to save, the repository can actually persist the new items as files, and if successful clear the list of new items to add.

AFAIK the point of the UoW is to manage the Save across multiple repositories (which combined are the logical unit of work that we want to commit).

I really like your question. I've used Uow / Repository Pattern with Entity Framework and it shows how much EF actually does (how the context tracks the changes until SaveChanges is finally called). To implement this design pattern in your example you need to write quite a bit of code to manage the changes.