25 posts tagged with "C#"

For many years I've been a big fan of using NSwag to generate TypeScript and CSharp clients for APIs. I've written about it before in Generate TypeScript and CSharp clients with NSwag.

You're likely aware of the popularity of excellent projects like tRPC which provide a way to use TypeScript end-to-end. However, if you're working in a polyglot environment where your back end is written in C# or [insert other language here], and your front end is written in TypeScript, then cannot take advantage of that. However, by generating front end clients from a server's OpenAPI specs, it's possible to have integration tests that check your front end and your back end are aligned.

This post will show you how to do that using NSwag.

Let's start with "why". Imagine you have an operation that you'd like to perform, but before that operation is performed, some other things need to take place first. Maybe it needs to be approved by someone, maybe you need an explicit record of what method is to be executed.

Now you could build a mechanism to manually cater for each scenario that triggered a method call. But that's a lot of boilerplate code for each implementation, and given we might want to cater for many scenarios, it wouldn't scale particularly well as an approach.

So how can we take a method call, serialise it, perhaps store it in a database, and then later rehydrate and execute?

Of late, I've been involved in work to integrate APIs into LLM interactions, using Semantic Kernel. This post is something of a brain dump on the topic. Given how fast this space is moving, I expect what is written here to be out of date, possibly even before I hit publish. But nevertheless, I hope it's useful.

I've recently been working on building retrieval augmented generation (RAG) experiences into applications; building systems where large language models (LLMs) can query documents. To achieve this, we first need a strategy to chunk those documents and make them LLM-friendly. Kernel Memory, a sister project of Semantic Kernel supports this.

Cosmos DB is a great database for storing objects. But what if you want to store subtly different types of object in the same container? This post demonstrates how you can use generics to store and retrieve different types of object in an Azure Cosmos DB Container using C#.

Writing tests is important. The easier it is to write tests, the more likely they'll be written. I've long loved snapshot testing for this reason. Snapshot testing takes away the need to manually write verification code in your tests. Instead, you write tests that compare the output of a call to your method with JSON serialised output you've generated on a previous occasion. This approach takes less time to write, less time to maintain, and the solid readability of JSON makes it more likely you'll pick up on bugs. It's so much easier to scan JSON than it is a list of assertions.

Loving snapshot testing as I do, I want to show you how to write high quality and low effort log assertions using snapshot testing. The behaviour of logging code is really important; it's this that we tend to rely upon when debugging production issues. But how do you test logging code? Well, you could write a bunch of assertions that check how your logger is used. But that's a lot of work, it's not super readable and it's not fun. (Always remember: if it's not fun, you're doing it wrong.)

Instead, we'll achieve this using snapshot testing.

The Graph API is a great way to get information about users in Azure Active Directory. I recently needed to get the names and ids of the Active Directory groups that a user was a member of. Here's how to do it with the C# SDK.

I'm writing this post as, whilst it ends up being a relatively small amount of code and configuration required, if you don't know what that is, you can end up somewhat stuck. This should hopefully unstick you.

Logs matter. In Azure, logs generally live in Application Insights, in the Transaction Search section. This post reverse engineers the Azure Application Insights Transactions URL, and details how to construct a link to take you directly there, using both TypeScript and C#.

ESLint provides a great linting experience for TypeScript and JavaScript in VS Code. The suggestions, fixes and ignore options make creating clean code a joy. A similar experience is available for C# in VS Code through Roslyn Analyzers - this post tells us more.

NSwag is a great tool for generating client libraries in C# and TypeScript from Open API / Swagger definitions. You can face issues where Open API property names collide due to the nature of the C# language, and when you want to use decimal for your floating point numeric type over double. This post demonstrates how to get over both issues.

.NET Core can make use of C# 9 by making some changes to your .csproj files. There is a way to opt all projects in a solution into this behaviour in a single place, through using a Directory.Build.props file and / or a Directory.Build.targets file. Here's how to do it.

C# 9 has some amazing features. Azure Functions are have two modes: isolated and in-process. Whilst isolated supports .NET 5 (and hence C# 9), in-process supports .NET Core 3.1 (C# 8). This post shows how we can use C# 9 with in-process Azure Functions running on .NET Core 3.1.

Generating clients for APIs is a tremendous way to reduce the amount of work you have to do when you're building a project. Why handwrite that code when it can be auto-generated for you quickly and accurately by a tool like NSwag? To quote the docs:

'Tis the season to play with new compiler settings! I'm a very keen TypeScript user and have been merrily using strictNullChecks since it shipped. I was dimly aware that C# was also getting a similar feature by the name of nullable reference types.

This post differs from my typical fayre. Most often I write "here's how to do a thing". This is not that. It's more "don't do this thing I did". And maybe also, "how can we avoid a situation like this happening again in future?". On this topic I very much don't have all the answers - but by putting my thoughts down maybe I'll learn and maybe others will educate me. I would love that!

If you're a user of Jest, you've no doubt heard of and perhaps made use of snapshot testing.

I hate LINQ's Enumerable.Concat when bringing together IEnumerables. Not the behaviour (I love that!) but rather how code ends up looking when you use it. Consider this:

So, you want to use C# 6 language features and you’re working on an older project that’s still rocking .NET 4.5. Well, with some caveats, you can.

So there I was, tip-tapping away at my keyboard when I became aware of the slowly loudening noise of a debate. It wasn't about poverty, war, civil rights or anything like that. No; this was far more contentious. It was about the behaviour of <a href="https://msdn.microsoft.com/en-gb/library/bb351562(v=vs.100).aspx">IQueryable&lt;T&gt;</a> when mixed with <a href="https://msdn.microsoft.com/en-gb/library/9eekhta0(v=vs.100).aspx">IEnumerable&lt;T&gt;</a>. I know, right, how could I not get involved?

I was recently reading a post by Jaime González García which featured the following mind-bending proposition: