MSDN Documentation: .NET Get Started

Understanding .NET Project Structure

A well-defined project structure is crucial for organizing your code, managing dependencies, and ensuring a maintainable .NET application. This guide will walk you through the common elements of a typical .NET project.

The Root Directory

At the top level of your project, you'll find several key files and folders:

.csproj file (or .vbproj, .fsproj): This is the project file. It contains metadata about your project, including its target framework, dependencies, output type, and build configurations. This is essential for the build process.
Program.cs (or Program.vb, Program.fs): This is typically the entry point of your application. It contains the Main method where execution begins. For newer C# versions (C# 9 and later), this file might be simplified with top-level statements.
obj folder: This folder contains intermediate build outputs. You generally don't need to interact with this folder, as it's managed by the .NET SDK during the build process.
bin folder: This folder contains the compiled output of your project (executables, libraries, etc.). It's usually divided into subfolders based on build configuration (e.g., Debug, Release) and target framework.

Common Subfolders

As your project grows, you'll typically create subfolders to organize different aspects of your application:

Properties: Contains assembly information files (like AssemblyInfo.cs) and application settings.
Controllers: (Common in ASP.NET Core) Holds your application's controllers, which handle incoming HTTP requests.
Views: (Common in ASP.NET Core MVC/Razor Pages) Contains your user interface files (e.g., Razor files .cshtml).
Models: Represents your application's data structures and business logic.
Services: Contains classes that implement business logic or interact with external resources.
Data: Often used for data access logic, such as Entity Framework Core DbContexts or repositories.
wwwroot: (Common in ASP.NET Core) A public folder for static files like HTML, CSS, JavaScript, and images.
Pages: (Common in ASP.NET Core Razor Pages) Contains your Razor Page files.
Tests (or Tests/UnitTests, Tests/IntegrationTests): A separate project or folder for your unit and integration tests.

Note: The exact structure can vary depending on the type of .NET project you are creating (e.g., Console App, ASP.NET Core Web API, WPF, Xamarin). However, the core principles of organization remain the same.

Example Project Structure (ASP.NET Core Web API)

YourWebApp/
├── YourWebApp.csproj
├── Program.cs
├── Properties/
│   └── launchSettings.json
├── Controllers/
│   └── WeatherForecastController.cs
├── Models/
│   └── WeatherForecast.cs
├── appsettings.json
└── README.md

The `.csproj` File

The project file is central to your .NET project. Here's a simplified example:

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.5.0" />
  </ItemGroup>

</Project>

Key elements include:

Sdk attribute defines the SDK used to build the project.
TargetFramework specifies the .NET version your project targets.
ItemGroup with PackageReference lists the NuGet packages your project depends on.

Important: Always ensure your .csproj file accurately reflects your project's dependencies and settings. The .NET CLI uses this file extensively.

Best Practices

Keep related files together: Place controllers, models, and views for a specific feature in the same folder or closely related folders.
Separate concerns: Use folders like Services and Data to separate business logic and data access from your presentation layer.
Organize tests: Create a dedicated project for your tests to keep the main application code clean.
Use a consistent naming convention: For files, folders, classes, and methods.