Let's do Some DDD With Entity Framework Core 3!

A few days ago, Microsoft released Entity Framework Core 3, introducing a lot of improvements in both functionality and performance (and some breaking change as well).

Now, we have full support for very cool stuff like C# 8, Async Enumerables, plus a brand new LINQ provider.

I’ve been using a lot of Entity Framework in my daily job, but of course, before upgrading a project ‘s dependency to a major version, there’s always some testing to do. As I often do, I decided to write a small demo and try out some of these new functionalities. You can find all the sources on GitHub.

My goal for this project was to model a bunch of Aggregates and Value Objects with proper Persistence Ignorance (e.g. I don’t want to pollute my business logic classes with code responsible for storing and retrieving data.

You may also like: How to Configure Entity Framework Caching.

Luckily, Entity Framework Core offers the possibility to configure the Entity/Table mapping using a nice Fluent Interface, avoiding attributes on our properties.

We have basically two options. The first one is to write all the configuration code in the OnModelCreating() method of our DbContext. It's quick and easy, but it leads to a lot of very confusing code.

A much cleaner option is to use the database diagram generated with https://sqldbm.com:

1. Create some products.
2. Add just one product to a quote and save it.
3. Update the quote adding another product.
4. Create an order from that quote.
5. Add another product to the quote.
6. Create another order from the quote.

In the next post, we’re going to take a look at the code and talk about each Entity configuration. Stay tuned!

Further Reading

• Domain-Driven Design Demystified.
• Teach Yourself DDD in 5 Minutes.
• 10 Easy Steps to a Complete Understanding of SQL.