C# Programming Language
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A .NET C# project fills up with files that should never be committed: build output in bin and obj, editor settings, and secrets such as .env. The .NET SDK ships a ready-made .gitignore that covers all of them, and one command adds it to your project. This guide adds it, shows what it ignores, and proves a file is really ignored.
The first build of a brand-new .NET 10 Web API failed with error CA1852 on the template's own WeatherForecast record. The solution turns on Microsoft's recommended code-quality rules and treats warnings as errors, and one of those rules asks for types like this one to be sealed. Adding that one word fixes it.
I created an ASP.NET Core Web API project inside a .NET 10 solution that manages package versions centrally, and the template's own restore failed with error NU1008. The template writes a package version into the project file, which central package management doesn't allow. Moving that one version to Directory.Packages.props fixes it.
Some code belongs only on a developer's machine: an in-memory store, a relaxed setting, a debugging aid. ASP.NET Core knows which environment it runs in, and one if around builder.Environment.IsDevelopment() keeps that code out of everywhere else. This guide shows the check, where to put it, and how to try the other branch on your own machine.
Most "deploy to the cloud" tutorials skip the part where you actually understand what you built. This series does the opposite: six short parts that take you from an empty folder to a real, public URL on Azure, explaining every command along the way.
Entity Framework Core maps each database table to an entity class and gives you a DbContext to query them. Most of the time you read from a single DbSet, but sooner or later you need data that lives across two tables — exactly what a SQL JOIN gives you. In EF Core, the lambda-based Join() method does the same job, and it translates into real SQL that runs on the database server.
Everything below targets .NET 10 and EF Core 10, the current Long Term Support releases.
appsettings.json is where an ASP.NET Core app keeps its settings — connection strings, API base URLs, feature flags, timeouts. Reading those values comes down to one service, IConfiguration, which ASP.NET Core registers for you. In a console app you build the same thing yourself in a few lines.
This guide covers both, on .NET 10.
When creating an AdapterWithErrorHandler class that inherits from CloudAdapter, you might encounter this compile error:
Argument 3: cannot convert from 'Microsoft.Extensions.Logging.ILogger<Microsoft.Agents.Hosting.AspNetCore.IAgentHttpAdapter>' to 'Microsoft.Extensions.Logging.ILogger<Microsoft.Agents.Hosting.AspNetCore.CloudAdapter>'
This happens because you're passing ILogger<IAgentHttpAdapter> to the CloudAdapter base constructor, but it expects ILogger<CloudAdapter>.
(2,1): error CS0131: The left-hand side of an assignment must be a variable, property or indexer. It's important to notice that assignment happens from right to left.
(2,9): error CS0029: Cannot implicitly convert type 'string' to 'int'. C# was designed to enforce types. When working with variables, enforcing types means.
