NOT using repository pattern, use the ORM as is (EF)

by

I’ve gone down many paths and created many implementations of repositories on different projects and… I’ve thrown the towel in and given up on it, here’s why.

Coding for the exception

Do you code for the 1% chance your database is going to change from one technology to another? If you’re thinking about your business’s future state and say yes that’s a possibility then a) they must have a lot of money to afford to do a migration to another DB technology or b) you’re choosing a DB technology for fun or c) something has gone horribly wrong with the first technology you decided to use.

Why throw away the rich LINQ syntax?

LINQ and EF were developed so you could do neat stuff with it to read and traverse object graphs. Creating and maintain a repository that can give you the same flexibility to do that is a monstrous task. In my experience any time I’ve created a repository I’ve ALWAYS had business logic leak into the repository layer to either make queries more performant and/or reduce the number of hits to the database.

I don’t want to create a method for every single permutation of a query that I have to write. I might as well write stored procedures. I don’t want GetOrder, GetOrderWithOrderItem, GetOrderWithOrderItemWithOrderActivity, GetOrderByUserId, and so on… I just want to get the main entity and traverse and include the object graph as I so please.

Most examples of repositories are bullshit

Unless you are developing something REALLY bare-bones like a blog or something your queries are never going to be as simple as 90% of the examples you find on the internet surrounding the repository pattern. I cannot stress this enough! This is something that one has to crawl through the mud to figure out. There will always be that one query that breaks your perfectly thought out repository/solution that you’ve created, and it’s not until that point where you second guess yourself and the technical debt/erosion begins.

Don’t unit test me bro

But what about unit testing if I don’t have a repository? How will I mock? Simple, you don’t. Lets look at it from both angles:

No repository – You can mock the DbContext using an IDbContext or some other tricks but then you’re really unit testing LINQ to Objects and not LINQ to Entities because the query is determined at runtime… OK so that’s not good! So now it’s up to the integration test to cover this.

With repository – You can now mock your repositories and unit test the layer(s) in between. Great right? Well not really… In the cases above where you have to leak logic into the repository layer to make queries more performant and/or less hits to the database, how can your unit tests cover that? It’s now in the repo layer and you don’t want to test IQueryable<T> right? Also let’s be honest, your unit tests aren’t going to cover the queries that have a 20 line .Where() clause and .Include()‘s a bunch of relationships and hits the database again to do all this other stuff, blah, blah, blah anyways because the query is generated at runtime. Also since you created a repository to keep the upper layers persistence ignorant, if you now you want to change your database technology, sorry your unit tests are definitely not going to guarantee the same results at runtime, back to integration tests. So the whole point of the repository seems weird..

2 cents

We already lose a lot of functionality and syntax when using EF over plain stored procedures (bulk inserts, bulk deletes, CTEs, etc.) but I also code in C# so I don’t have to type binary. We use EF so we can have the possibility of using different providers and to work with object graphs in a nice related way amongst many things. Certain abstractions are useful and some are not.

More Related Contents:

  1. Entities VS Domain Models VS View Models
  2. Entity Framework: One Database, Multiple DbContexts. Is this a bad idea? [closed]
  3. No Entity Framework provider found for the ADO.NET provider with invariant name ‘System.Data.SqlClient’
  4. Entity Framework and SQL Server View
  5. How to mock the limitations of EntityFramework’s implementation of IQueryable
  6. EF Including Other Entities (Generic Repository pattern)
  7. EntityFramework code-first custom connection string and migrations
  8. How to implement the activity stream in a social network
  9. how to update an entity in Entity Framework 4 .NET
  10. Should I enable or disable dynamic proxies with entity framework 4.1 and MVC3?
  11. An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key
  12. Entity Framework 4 / POCO – Where to start? [closed]
  13. Asp.Net Web API Error: The ‘ObjectContent`1’ type failed to serialize the response body for content type ‘application/xml; charset=utf-8’
  14. Generate POCO classes in different project to the project with Entity Framework model
  15. Entity Framework: Ignore Columns
  16. Querying objects after AddObject before SaveChanges?
  17. PropertyGrid Browsable not found for entity framework created property, how to find it?
  18. Entity framework PostgreSQL
  19. Loop/reflect through all properties in all EF Models to set Column Type
  20. mapping private property entity framework code first [duplicate]
  21. MVC3 and Code First Migrations – “model backing the ‘blah’ context has changed since the database was created”
  22. EF can’t infer return schema from Stored Procedure selecting from a #temp table
  23. How to create index in Entity Framework 6.2 with fluent configuration
  24. Using Entity Framework with an SQL Compact Private Installation
  25. Mocking or faking DbEntityEntry or creating a new DbEntityEntry
  26. Map two different entities to the same table?
  27. View Models and dependency injection
  28. DbContext AutoDetectChangesEnabled set to false detecting changes
  29. Using the Entry().CurrentValues.SetValues() is not updating collections
  30. .NET 4.5 Beta DbGeography NotImplementedException

Leave a Comment