Practical articles about .NET and C#, from quick tips to deep dives: performance, testing, diagnostics, Roslyn analyzers, MSBuild, NuGet, PowerShell, and git.Mon, 28 Sep 2026 12:00:00 GMThttps://www.meziantou.net/?utm_medium=social&utm_source=syndicationIn , we used JsonNode as the input type. If your data is already loaded in domain classes, you can evaluate JsonPath directly on those classes without converting to JsonNode. Meziantou.Framework.JsonPath exposes JsonPathNavigator<TValue> for this scenario. You provide JSON-like navigation semantics for your node type, and the evaluator does the rest. This is the same approach as in , where we exposed…https://www.meziantou.net/adding-jsonpath-support-to-custom-object-models-in-dotnet.htm?utm_medium=social&utm_source=syndication79429f3e-7781-4012-9f75-ec73b0e98437Gérald BarréMon, 28 Sep 2026 12:00:00 GMT.NETWhen you need to extract values from complex JSON payloads, manual navigation quickly becomes hard to read and maintain. Meziantou.Framework.JsonPath provides a JSONPath implementation for System.Text.Json based on RFC 9535, so you can query JSON documents using concise, standard expressions. Installation Install the package from NuGet: dotnet add package Meziantou.Framework.JsonPath Parse and evaluate a…https://www.meziantou.net/using-jsonpath-with-system-text-json-to-query-json-in-dotnet.htm?utm_medium=social&utm_source=syndication5ea8dd48-6ec5-476d-8d39-b9dce811bcc7Gérald BarréMon, 21 Sep 2026 12:00:00 GMT.NETIn , I showed that XPathNavigator is not tied to XML. Any tree can be exposed as a node-set, and the XPath engine of System.Xml.XPath does the rest. That post used a folder hierarchy as an example. Here is a much more interesting tree: the C# syntax tree produced by Roslyn. The occasion for it was an issue on Meziantou.Analyzer: Rule to forbid primary constructors? (Opposite of IDE0290). The request was…https://www.meziantou.net/querying-roslyn-syntax-trees-with-xpath.htm?utm_medium=social&utm_source=syndicationa013cf7e-2dac-4727-9240-74fa2f79697fGérald BarréSun, 20 Sep 2026 12:00:00 GMTRoslyn.NETXPath is widely known as the query language for XML documents. Most .NET developers associate it with XPathNavigator, XmlDocument, or XDocument. But what most people don't realize is that XPath can work with custom types too. In this post, I'll show you how to implement XPath for your own types and how it can be useful for searching complex object hierarchies. The problem Imagine you have a rich object…https://www.meziantou.net/xpath-for-custom-types-in-dotnet.htm?utm_medium=social&utm_source=syndicationd6dbd2bc-76f7-470e-8c6c-94d5e4286f8aGérald BarréMon, 14 Sep 2026 12:00:00 GMT.NETIntegration tests are much more valuable when they run against real services. Instead of mocking a database or cache, you can start a temporary container, run your test, and dispose everything at the end. The Meziantou.Framework.TemporaryContainers package provides a lightweight API to manage disposable containers from .NET. Its main difference with the existing libraries is that it is not tied to Docker.…https://www.meziantou.net/run-temporary-containers-in-dotnet-tests-with-meziantou-framework-temporaryconta.htm?utm_medium=social&utm_source=syndicationa98cd9bd-d1ef-4bf7-a6b8-94bfec99787eGérald BarréMon, 07 Sep 2026 12:00:00 GMT.NETWhen maintaining a library, one of the easiest ways to introduce a breaking change is to update a public type without noticing its impact on consumers. You can use the Microsoft.CodeAnalysis.PublicApiAnalyzers analyzer to generate a file with the list of members. However, I don't like it as the members are not in C# syntax. Also, if you don't have the same public API for all target frameworks, you get…https://www.meziantou.net/generate-and-review-the-public-api-of-a-dotnet-library.htm?utm_medium=social&utm_source=syndicationbbd64a77-f19c-430c-8a4e-1d29175687ffGérald BarréMon, 31 Aug 2026 12:00:00 GMT.NETToolsWhen you add a NuGet package to a project, you often think about the runtime library only. In reality, packages can also import MSBuild props/targets and Roslyn analyzers. Those assets run during restore, design-time build, or build. I've already provided some examples of how this can cause issues in . This means a package can execute code on your machine or in CI without you notice. If you only need a…https://www.meziantou.net/limit-what-nuget-packages-can-do-in-your-project.htm?utm_medium=social&utm_source=syndication3453480d-0f10-47ad-9129-1e8c264e2da3Gérald BarréMon, 24 Aug 2026 12:00:00 GMT.NETSecuritySnapshot testing is a technique where the output of a function or component is serialized and saved to disk the first time the test runs. On every subsequent run, the library re-serializes the output and compares it against the saved file. If they differ, the test fails. Meziantou.Framework.SnapshotTesting is a .NET library that makes snapshot testing straightforward. It handles serialization, file…https://www.meziantou.net/snapshot-testing-in-dotnet-with-meziantou-framework-snapshottesting.htm?utm_medium=social&utm_source=syndication2f5d26e6-6888-471e-9574-dbbd2a86eae9Gérald BarréMon, 10 Aug 2026 12:00:00 GMT.NETToolsAdding a Clone method to a C# record When using records, creating a copy with with is concise: var sample = new Sample("meziantou"); _ = sample with { }; public record Sample(string Value); This works well, but sample with { } is not always obvious as a discoverable Clone API for consumers. Why public Sample Clone() is not allowed Records already have compiler-generated clone behavior used by with.…https://www.meziantou.net/adding-a-clone-method-to-a-csharp-record.htm?utm_medium=social&utm_source=syndicationa5db1822-ce6a-42d0-9ab9-e83d093d66dcGérald BarréMon, 03 Aug 2026 12:00:00 GMT.NETIf you have a Rune and want its Unicode name (for example GRINNING FACE for 😀), there is no built-in API in .NET today. Here are two practical options: Use the ICU library available on the operating system Use the Meziantou.Framework.Unicode NuGet package Method 1: Use ICU from the OS ICU exposes u_charName, which returns the Unicode name for a code point. using System; using…https://www.meziantou.net/get-a-unicode-character-name-from-a-rune-in-dotnet.htm?utm_medium=social&utm_source=syndicatione6921c34-c757-4fae-a8b2-f57c738d6bc4Gérald BarréMon, 27 Jul 2026 12:00:00 GMT.NET