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When to validate commands in CQRS?
Everything else should go to the domain model or commands handlers. This will help you keep a good separation between ASP.NET-related and application-related concerns. Even trivial validations, such as checking for nulls, field lengths and so on, should go to the domain model in an ideal case.
Where does validation occur in a command handler?
Typically you would have a validation that occurs on the UI and that might be duplicated inside the command handler (some people tend to put it in the domain too). Command handler then can run simple validation that can occur outside of the entity like is data in correct format, are there expected values, etc.
When to validate commands in the domain model?
Ideally, all validations should reside either in command handlers or in the domain model. The drawback of this approach is its complexity. In simpler projects, use attributes to streamline the validation. This approach is not as pure, but it’s simpler. Are CQRS commands part of the domain model? ← Are CQRS commands part of the domain model?
How are exceptions handled in the new CQR?
You shouldn’t covert into Result exceptions that you don’t intend to process, which is exactly what we did in the new version. Now all database connectivity exceptions are converted into Result values, even when there’s no decorator on top of the command handler. Such exceptions will simply be ignored.
Do you need separate domain model for CQRS?
CQRS does not require using separate domain model for queries and commands. It is often logical to go that route, but you could also use separate domain model for queries and commands, yet do not segregate the responsibilities.
What is Command query responsibility segregation ( CQRS )?
Command Query Responsibility Segregation (CQRS) is a pattern that causes quite a lot of confusion. With the popularity of microservices and the event-based programming model, it is important to know what CQRS is. In this article, I will provide you with a simple explanation.
Can a CQR be used without an event?
Although the CQRS can be used without events, they do complement each other so its common for systems that use CQRS to leverage the use of events. Events are one way to effectively communicate state changes so that the query model can stay up to date as the command model updates data.