Query Filters and Automated Audit Columns

I wanted to write a quick post about using query filters and automatically populating audit columns in Entity Framework Core since I see a lot of people doing this manually still. A common scenario in most applications is to do soft deletes on everything, typically with a column like “IsDeleted”. Another common scenario that is found almost universally in every system are audit columns like “DateCreated” and “DateUpdated”. This is actually very simple to implement, so this is going to be a fairly short post.
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Maximizing Entity Framework Core Query Performance

Entity Framework Core query performance is something that comes up often when working on projects that rely on it heavily. I have often heard that Entity Framework is not performant enough which then leads to everything being written as a stored procedure. Usually this happens for two main reasons: developers aren’t familiar with how to write queries in a performant manner and developers that are more comfortable with SQL want to develop everything in their technology of choice. Entity Framework is not a silver bullet for everything. There are times when it simply can’t deliver the performance needed or when it is simply functionally incapable of doing what is necessary due to limitations of the framework. That being said, there is no reason you can’t write the vast majority of your application with it and reap all the benefits it provides.
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IdentityServer4 in ASP.NET Core Part 1

If you’ve worked with APIs at all in .NET Core then you have probably had the need to work with tokens for security. You could roll your own set up just using the underlying functionality in ASP.NET Identity, or you could enable easy mode and use something like IdentityServer4. There are other options out there for you to choose from, but this post will focus on IdentityServer4. Our application is going to consist of an API, a web application for IdentityServer4 and a Javascript based client. The source code for this post can be found here.
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Using an Angular Shared Service

An Angular shared service is a powerful tool to allow cross component communication. If you’ve used other Javascript frameworks like Backbone or Vue then you are already probably familiar with the concept of a service bus. In Angular, a shared service is what provides what is essentially a pub/sub messaging pattern. Before Typescript and the componentized approach that we see in modern Javascript libraries, the service bus could become a source of problems. This was due to the fact that you could have any number of scripts publishing and subscribing to messages, but no easy to way to find which scripts were doing it other than to do a simple search. Debugging was especially painful, at least my experience with Backbone was.
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Angular Interceptors

One of the great things that the new Javascript frameworks have introduced are practices that would normally be found on the server. Personally I am holding out hope for WASM and Blazor to save us from Javascript once and for all. That doesn’t mean we can’t improve our quality of life though by using what is currently on offer. Angular and its contemporary Javascript framework counterparts are light years ahead of JQuery. JQuery served its purpose for its time, but it’s time to move on, and building green field applications with it is a non-starter for me.
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Think Before You Use The DTO Pattern

Let me preface this blog post by saying that there are still times when a DTO makes sense. Also, this post is written from a .NET perspective, so some things may be different on your platform. What I want to address though is the tendency of many developers to just automatically create a set of DTOs for each layer for each domain model. As I mentioned in other blog posts, you should always think about why you are doing something before you are doing it. Continue reading “Think Before You Use The DTO Pattern”

The Repository Pattern is Dead If You Use Entity Framework

That is, it’s dead if you are using Entity Framework Core. If you’re still using straight ADO.NET, or even just dapper, then the repository pattern still probably makes sense for you. If you’re using Entity Framework, then you really aren’t gaining much from doing so anymore. Five years ago, you could reasonably argue that it was beneficial to use the repository pattern, or some form of abstraction, over entity framework for the following reasons:
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ASP.NET Core Request Post Processing

If you’ve worked with Asp.Net Core to create APIs then you have more than likely run into situations where you needed to return different sets of data for the same model. One way to accomplish this is request post processing using an ActionFilter. Lets start with a common scenario. We have an internal enterprise application and we have different types of users in the system. Users can call our API to get data on other users depending on their permission levels. We have three different types of users: Admin, HelpDesk, and Employee. Our class looks like this:
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Dealing with Validation – Domain vs Contextual

I’ve always found validation to be one of the most difficult and tedious aspects of writing enterprise software. No matter how you organize your rules, you are going to usually end up with duplication. To make matters worse, the rules aren’t written by developers, they are created by the business. This causes a disconnect between knowledge and domain experts, and the people who are implementing the validation in the code. As the rules change over time, and as the developers who originally worked on the system move on, the validation becomes increasingly difficult to manage. As the system matures, it ultimately ends up becoming a significant source of pain for all those involved. That’s assuming, of course, that you even have validation in the first place.
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