Don't use Ids in your domain entities!
How often do you see code like this in your domain model? public void Ship(int orderId, int customerId, string address) { Shipment shipment = _existingShipments.Single(x => x.OrderId == orderId); if (shipment.CustomerId == customerId) { // Do something } } Seems pretty good, doesn’t it? Well, it doesn’t. I’ve already pointed using Ids in domain entities as a bad practice, but I see developers - even sophisticated ones - write such code over and over again, so this topic definitely deserves a separate article.
Async/await in C#: pitfalls
I’d like to discuss some common pitfalls of async/await feature in C# and provide you with workarounds for them.
I/O Threads Explained
Microsoft has released async/await feature in .Net 4.5. It’s a really great stuff as it significantly simplifies one of the most painful areas - asynchronous programming. Before that, Task Parallel Library (TPL) and Parallel LINQ (PLINQ) were released in .Net 4.0. They address problems with parallel programming - another painful area in .Net.
I often see programmers struggling with a question when to use each of these features. Let’s step back and recall what does it actually mean to be asynchronous or parallel.
Separation of Concerns in ORM
Last week we compared Entity Framework and NHibernate from a DDD perspective. Today, I’d like to dive deeper into what Separation of Concerns (SoC) is and why it is so important. We’ll look at some code examples and features that break the boundaries between the domain and persistence logic. Separation of concerns in ORM There are several concerns we deal with in software development. In most applications, there are at least three of them clearly defined: UI, business logic and database.
C# Read-Only Collections and LSP
I often see programmers saying that .NET read-only collections violate Liskov Substitution Principle. Do they? The quick answer is no but let’s go through the whole story first.
CQS with Database-Generated Ids
Mark Seemann brings up a very interesting subject in his post: how to fit Command Query Separation principle in case you have to save a brand-new object in a database and also need the created id back? Sure, you can have GUIDs for identifiers (which have some drawbacks as I’ll show later on), but what if you really need integers? I’ve been asked the same question for several times, so in this post I’ll share the solution I use for this problem.
Entity Base Class
If you follow DDD principles, you eventually end up creating a base class for all the domain entities. It’s a good idea as it allows you to gather common logic in one place. When you decide to do that, you inevitably face the question what exactly should be included in that base entity and how it should be presented.
What is enterprise development?
It’s the first post on the blog I’m starting today. The idea to start blogging was with me quite for a while, so I decided to give it a try.
