SSW.VerticalSliceArchitecture.Template 2025.10.24

SSW Vertical Slice Architecture Template

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SSW Vertical Slice Architecture Template

• 🤔 What is it?
• ✨ Features
• 🎉 Getting Started
• 🎓 Learn More
• 🚀 Publishing Template
• 🤝 Contributing

🤔 What is it?

An enterprise ready solution template for Vertical Slice Architecture. This template is just one way to apply the Vertical Slice Architecture.

Read more on SSW Rules to Better Vertical Slice Architecture

✨ Features

• 🔨 dotnet new cli template - to get you started quickly

• 🚀 Aspire

  • Dashboard
  • Resource orchestration
  • Observability
  • Simple dev setup - automatic provisioning of database server, schema, and data

• 🎯 Domain Driven Design Patterns

  • AggregateRoot
  • Entity
  • ValueObject
  • DomainEvent

• ⚡ FastEndpoints - developer friendly alternative to Minimal APIs.

  • Strongly-typed requests and responses
  • Automatic validation with FluentValidation
  • Support for commands and events

• 📝 OpenAPI/Swagger - easily document your API

  • as per ssw.com.au/rules/do-you-document-your-webapi/

• 🔑 Global Exception Handling - it's important to handle exceptions in a consistent way & protect sensitive information

  • Transforms exceptions into a consistent format following the RFC7231 memo

• 🗄️ Entity Framework Core - for data access

  • Comes with Migrations & Data Seeding
  • as per ssw.com.au/rules/rules-to-better-entity-framework/

• 🧩 Specification Pattern - abstract EF Core away from your business logic

• 🔀 REPR (Request-Endpoint-Response) Pattern - for structured endpoints

• 📦 ErrorOr - fluent result pattern (instead of exceptions)

• 📦 FluentValidation - for validating requests

  • as per ssw.com.au/rules/use-fluent-validation/

• 🆔 Strongly Typed IDs - to combat primitive obsession

  • e.g. pass CustomerId type into methods instead of int, or Guid
  • Entity Framework can automatically convert the int, Guid, nvarchar(..) to strongly typed ID.

• 📁 Directory.Build.Props

  • Consistent build configuration across all projects in the solution
    • e.g. Treating Warnings as Errors for Release builds
  • Custom per project
    • e.g. for all test projects we can ensure that the exact same versions of common packages are referenced
    • e.g. XUnit and NSubstitute packages for all test projects

• ⚖️ EditorConfig - comes with the SSW.EditorConfig

  • Maintain consistent coding styles for individual developers or teams of developers working on the same project using different IDEs
  • as per ssw.com.au/rules/consistent-code-style/

• 🧪 Testing

  • as per ssw.com.au/rules/rules-to-better-testing/
  • Simpler Unit Tests for Application
    • No Entity Framework mocking required thanks to Specifications
    • as per ssw.com.au/rules/rules-to-better-unit-tests/
  • Better Integration Tests
    • Using Respawn and TestContainers
    • Integration Tests at Unit Test speed
    • Test Commands and Queries against a Real database
    • No Entity Framework mocking required
    • No need for In-memory database provider

• Architecture Tests

  • Using NetArchTest
  • Know that the team is following the same Vertical Slice Architecture fundamentals
  • The tests are automated so discovering the defects is fast

🎉 Getting Started

Prerequisites

• Docker / Podman
• Dotnet 9

Installing the Template

1. Install the SSW VSA template

   dotnet new install SSW.VerticalSliceArchitecture.Template
   

[!NOTE] The template only needs to be installed once. Running this command again will update your version of the template.

2. Create a new directory

   mkdir Sprout
   cd Sprout
   

3. Create a new solution

   dotnet new ssw-vsa
   

[!NOTE] name is optional; if you don't specify it, the directory name will be used as the solution name and project namespaces.

Alternatively, you can specify the name and output directory as follows:

dotnet new ssw-vsa --name {{SolutionName}}

Running the Solution

1. Change directory<br /> Windows:

   cd tools\AppHost\
   

   Mac/Linux:

   cd tools/AppHost/
   

2. Run the solution

   dotnet run
   

[!NOTE] The first time you run the solution, it may take a while to download the docker images, create the DB, and seed the data.

4. Open https://localhost:7255/swagger in your browser to see it running ️🏃‍♂️

Adding Features

Adding a Feature Slice

To speed up development there is a dotnet new template to create a full Vertical Slice:

• Creates a domain object in Common/Domain/*
• Adds domain configuration in Common/Persistence/*
• Creates Command & Query API endpoints in Features/*

1. Add a new Feature

   cd src/WebApi/
   dotnet new ssw-vsa-slice --feature Person --feature-plural People
   

--feature or -f where the value is the singular name of the feature. --feature-plural or -fp where the value is the plural name of the feature.

2. Configure this Feature This project uses strongly typed IDs, which require registration in the VogenEfCoreConverters class:

   // Register the newly created Entity ID here
   [EfCoreConverter<PersonId>]
   internal sealed partial class VogenEfCoreConverters;
   

3. Add a migration for the new Entity

   dotnet ef migrations add --project src/WebApi/WebApi.csproj --startup-project src/WebApi/WebApi.csproj --output-dir Common/Database/Migrations PersonTable 
   

EF Migrations

Due to .NET Aspire orchestrating the application startup and migration runner, EF migrations need to be handled a little differently to normal.

Adding a Migration

Adding new migrations is still the same old command you would expect, but with a couple of specific parameters to account for the separation of concerns. This can be performed via native dotnet tooling or through the Aspire CLI:

1. Run either of following commands from the root of the solution.

dotnet ef migrations add YourMigrationName --project ./src/Infrastructure/Infrastructure.csproj --startup-project ./src/WebApi/WebApi.csproj --output-dir ./Persistence/Migrations

aspire exec --resource api -- dotnet ef migrations add YourMigrationName --project ../Infrastructure/Infrastructure.csproj --output-dir ./Persistence/Migrations

Applying a Migration

.NET Aspire handles this for you - just start the project!

Removing a Migration

This is where things need to be done a little differently and requires the Aspire CLI.

1. Enable the exec function:

aspire config set features.execCommandEnabled true

2. Pass the EF migration shell command through Aspire from the root of the solution:

aspire exec --resource api -- dotnet ef migrations remove --project ..\Infrastructure --force

Deploying to Azure

The template can be deployed to Azure via the Azure Developer CLI (AZD). This will setup the following:

• Azure App Services: API + MigrationService
• Azure SQL Server + Database: Data storage
• Application Insights + Log Analytics: For monitoring and logging
• Managed Identities: For secure access to Azure resources
• Azure Container Registry: For storing Docker images

Steps to Deploy

1. Authenticate with Azure

   azd auth login
   

2. Initialize AZD for the project

   azd init
   

3. Update environment variables

   azd env set ASPNETCORE_ENVIRONMENT Development
   

4. Deploy to Azure

   azd up
   

🎓 Learn More

graph TD;
    subgraph ASP.NET Core Web App
        subgraph Slices
            A[Feature A]
            B[Feature B]
        end
        Slices --> |depends on| Common
        Host --> |depends on| Common
        Host --> |depends on| Slices
        ASPNETCore[ASP.NET Core] --> |uses| Host
    end

    Common[Common]

🚀 Publishing Template

Template will be published to NuGet.org when changes are made to VerticalSliceArchitecture.nuspec on the main branch.

Process

1. Update the version attribute in VerticalSliceArchitecture.nuspec
2. Merge your PR
3. package GitHub Action will run and publish the new version to NuGet.org
4. Create a GitHub release to document the changes

[!NOTE] We are now using CalVer for versioning. The version number should be in the format YYYY.M.D (e.g. 2024.2.12).

🤝 Contributing

Contributions, issues and feature requests are welcome! See Contributing for more information.