Category Archives: DDD

New EF Core and Domain-Driven Design Course on Pluralsight!

MY NEW Pluralsight COURSE IS OUT! EF Core 6 and Domain-Driven Design. Yippee! I spent 3 months heads down on this (and years preparing for it!)

This happily aligns with a current 50% off sale on annual subscriptions.

Also note that as with *all* PS courses, they are limited to “expanded” library for the first few days but this will be part of the standard library (available to all) hopefully by the end of this week.

Short description
“Data persistence is important to your application workflow. This course will teach you how to use Entity Framework Core 6 and 7 effectively to persist data from your DDD designed software.”

The module titles should give you a better flavor of this course:

  • Understanding Where EF Core 6 Fits Alongside DDD (Includes an overview of DDD)
  • Analyzing and Planning Our Domain (Strategic and tactical design walkthrough)
  • Exploring the Contract Bounded Context Solution
  • Adding the First EF Core DbContext
  • Tuning Default Mappings for the Data Model
  • Using Integration Tests to Validate Persistence
  • Reasoning About Many-to-Many Variations
  • Mapping Aggregates to Azure CosmosDB
  • Organizing Persistence Logic to Support DDD Design (Repositories, services, search and sharing data and events across bounded contexts)


Links to My Recent DDD+EFCore Content

Time to aggregate the various articles and videos I’ve created filled with lessons on how EF Core support for direct mapping of domain models to your relational databases has been improving:

Completely New EF in the Enterprise Course on Pluralsight

My baby is here! A brand new Entity Framework in the Enterprise.

[See also:  New EF Core Course on Pluralsight!]

In 2012, I published a course on Pluralsight called Entity Framework in the Enterprise. Since then I have learned so much, most importantly, I’ve become very active with Domain-Driven Design, even publishing the DDD Fundamentals course that I co-created with Steve Smith. This has had a big impact on how I think about designing and architecting software and in turn,how I approach incorporating EF in to large, complex applications.

I’ve been wanting to re-do that old course to share my new views. I finally began in January of this year, but had a 3 month conference travel hiatus. So while it feels like a baby that I spent 9 months on, it was really only 6 months. Still quite a long time!

The course is now live! Entity Framework in the Enterprise

In the course, I use VS2015 and EF6. Why EF6? Because EF Core is too new. Most of the patterns I discuss and demonstrate are totally applicable to EF Core. There is one thing that is not yet in EF Core: Value Objects, but that is coming. Also the module on testing focuses on mocking and does not take EF Core’s new In Memory provider into account. Other than that, you can use what you learn here with EF Core as well.

I put a lot of thought into this course and I think this comment on the discussion forum for the course expresses it so well:

I just watched Julie Lerman’s prior Entity Framework in the Enterprise three weeks ago, before this new course was released, and boy am I glad she’s updated the course. I had thought the previous version was a bit dated (2016 vs 2012 & EF6 vs EF4) and a bit basic with what Julie refers to as Demo Ware. This updated course goes into more details about architecting projects, improved Moq testing with EF6, and a better explanation of DDD with Bounded Contexts using Schema to segregate areas. I already had a good understanding of EF, DDD, Repositories, UoW, and CQRS before watching and while I wouldn’t set up things 100% this way in my own applications they did jump start some refactorings and rethinking on how I maintain my solution, which is the purpose of these courses, to give fresh ideas as technology evolves, just as Entity Framework has. Thanks for updating the course and for those who have watched the previous version, definitely give this new one a watch.


ICYMI, My General Advice re DDD, EF & Domain Models with or without Data Models

I wrote this in a Github issue thread about EFCore & lack of current support for complex types (which support DDD Value Objects .. to a degree) this morning and someone said I should share it so here it is:

I love value objects. I’m just not considering efcore for any serious work yet so I am not going to stress out about not using them. I find myself designing my domain with them out of habit then having to undo. And if you are set on efcore, then +++ to @jnm2 ‘s point. I map from domain to EF’s data model (the in-memory model that EF infers at runtime) using EF’s mapping when it’s easy and I don’t have to make annoying (or worse) concessions. Otherwise it is time for a mapper between domain and data model defined by separate classes + EF DBContext. So EF mapping layer is my default mapper when using EF. But sometimes it is just not sufficient and I go to (or recommend) the effort of building a separate data model. Your choice. Pick your battles.

Another point is that Jimmy Bogard doesn’t even think the ef6 complex types do enough to map types that you’ve defined as value objects. So he’s been either just using one to one or going the extra mapper route depending on the situation. Gogglebing Jimmy Bogard, something like “what’s missing in ef6 for DDD” to read more. And then there’s that collection conundrum, too as well as the problem of mapping private fields. So if you are okay without those in EF6, maybe support for value objects isn’t such a huge deal except for the problem of it being “taken away” temporarily.

My ref to Jimmy Bogard was for his Domain modeling with Entity Framework scorecard post.

I’m sharing because of the following reply from Joseph Musser on this thread:

I would love to have had (and still would love) an article that thoroughly addresses that question: weighing the pros and cons of staying within EF modeling constraints or using a data model and mapping yourself. When to consider making the switch. And what that means for creating a rich, disciplined model that doesn’t become anemic. I feel like I’ve wasted a lot of time not having a fundamental understanding of this from the beginning.

A Pattern for Sharing Data Across Domain-Driven Design Bounded Contexts

My latest MSDN Magazine column  – October 2014 issue – has just gone live.

A Pattern for Sharing Data Across Domain-Driven Design Bounded Contexts
Julie Lerman explores a way to mirror data as one scenario for sharing data across DDD bounded contexts.

Even though the solution is available for download, it involves installing and running RabbitMQ and learning my way around the server’s UI. For me that was a fun and almost freeing step of building the solution. It even meant installing Erlang on my laptop. Lots of fun but lots of learning curves.

But it may be more than some readers want to commit to. So I recorded a video of me debugging through the solution so that you can see how it works.

I recommend reading the article first and watching the Domain-Driven Fundamentals course that Steve Smith and I created for Pluralsight will really help. If you don’t have a Pluralsight subscription yet (really?) send me a message through my contact form and I can hook you up with a free trial. Warning…can lead to addiction.

Anyway, here is the video. There is no sound…I’ve used captions to explain. [youtube]

DDD Fundamentals Course is Making a Difference

Steve Smith and I are so happy to be getting this kind of feedback about our Domain-Driven Fundamentals course on Pluralsight. We wanted to give developers help understanding the basics so that they can dig in to more indepth resources like Eric Evans’ or Vaughn Vernon’s books.

Here are some recent tweets we’ve seen.

Ryan Moseley @bahamaboy85

Completed the DDD Fundamentals course from @pluralsight by @ardalis @julielerman …. This course makes DDD accessible.

It is tough to find DDD examples that don’t assume some level of knowledge. So this course is welcomed.

Tom Davis @photomoose · Sep 9

@julielerman Just watched your DDD course on @pluralsight. Probably the best intro to DDD I’ve seen; things make sense now!

Paul Hale @paulhale · Aug 29

@pluralsight @ardalis @julielerman cracking #DDD course + @ericevans0 book set me on right track. Ironically Im building a domain reg system

Félix-A. Bourbonnais @fbourbonnais · Aug 11

Good #DDDDesign course by @julielerman @ardalis. Key concepts of DDD are well explained. I recommend

Geoff Mazeroff @geoffmazeroff · Jul 30

My work project uses DDD, so I enjoyed hearing @ardalis and @julielerman present the fundamentals on their @Pluralsight course. Nice work!

Mike Sussman @mikesussman · Jul 25

Finished @pluralsight DDD Fundamentals course by @julielerman and @ardalis, makes a lot more sense now.