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Derek Comartin

Validating Commands with the Decorator Pattern

This post is how I have manged to handle validating commands and queries and belongs to a series about different aspects of applying CQRS Although these examples are demonstrating usage in commands, they are aslo applicable to queries. Examples are using using MediatR to handle our requests. If you are unfamiliar with CQRS or MediatR, here are some other relevant posts: Organize by Feature Thin Controllers with CQRS and MediatR Query Objects instead of Repositories Mediator Pattern using MediatR and Unity Feature First let’s take a look at our feature for Changing a Customers Pricing Level.  In this example I’ve organized… Read More »Validating Commands with the Decorator Pattern

Organize by Feature

This post is about how I organize by feature.  Features being my commands and queries. If you have not familiar with CQRS, it may be worth a look at some of my other posts to get some Context. Thin Controllers with CQRS and MediatR Query Objects instead of Repositories Mediator Pattern using MediatR and Unity  Layers What I found interesting was as I moved from thinking about layers to thinking about features and vertical slices, I didn’t immediately organize my code that way.  I would still organize my code by what it represented (eg layer). My project structure would look something like this:… Read More »Organize by Feature

Idempotent Aggregates

This blog post will cover creating Idempotent Aggregates and is apart of a series of posts related. Please take a look any previous posts as they may give more context to the code samples below. Thin Controllers with CQRS and MediatR Identify Commands & Events Idempotent Commands Follow @codeopinion Idempotence Idempotence is the property of certain operations in mathematics and computer science, that can be applied multiple times without changing the result beyond the initial application. In my previous post Idempotent Commands, I looked at creating idempotency at the persistence level if you are using an ACID compliance database. But what happens… Read More »Idempotent Aggregates