Why do we need to use Unit of Work when using EF?

Question

I have read that EF DbContext is UOW and DbSet is a generic repository, then why do we need to use UOW?

Sachin Singh · Answer

There can be a debate on this, i have seen developers with 10-12 years of experience. They include update and save in their Repository class which i personally think is violation of the exact meaning of Repository . what does a repository actually mean? A repository is only a collection of domain objects, now tell me have you ever seen below code var list = new List int >(); list.Save(); // doesn't exist! list.Update(); // doesn't exist! 3. What you see is list.Add(1); list.Remove(1); list.Find(1); 4. Clearly , Save and Update is not a part of Collection, so your Repository should not Contain Save and Update. Yes , DbSet is a Generic Repository that is the reason you only see Add , AddRange , Remove and Find methods on this, you will never see Save or Update on DbSet. Then , Where to keep Save and Update method ? This is exactly where you need UOW, to maintain database inetegrety , either all operation fail or all commit. Yes, DbContext is UOW , that is the reason you see SaveChanges() and Entry () method here. Then do we need UOW explicitely? UOW is the place (class) where all your Concerete Repository resides as a get only property, and all your repository shares the comman or single instance of DbContext thus maintain database integrity. public GenericRepository CRM_ContactRepository { get { if ( this ._CRM_ContactRepository == null ) this ._CRM_ContactRepository = new GenericRepository ( _context ); return _CRM_ContactRepository; } } public GenericRepository CRM_ProductRepository { get { if ( this ._CRM_ProductRepository == null ) this ._CRM_ProductRepository = new GenericRepository ( _context ); return _CRM_ProductRepository; } } As you can see both Repository shares the same instance of DbContext.

Nisha Regil · Answer

May be this can be helpful to understand. https://gunnarpeipman.com/ef-core-repository-unit-of-work/