VincentH-Net/GenerateOpenApiOnBuildFromNet8MinimalApi.md

## GenerateOpenApiOnBuildFromNet8MinimalApi.md

      
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              GenerateOpenApiOnBuildFromNet8MinimalApi.md
            
          
    To generate OpenApi.json on build from an ASP.NET 8 Minimal API, follow these steps:


In Visual Studio for Windows 17.7.0 or later, create a new ASP.NET Core API project


Follow these instructions to install Swashbuckle.AspNetCore.Cli as a local dotnet tool in your project


Add these NuGet packages (or later versions) to the project:


  <ItemGroup>
  	<PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.0-preview.4.23260.4" />
  	<PackageReference Include="Swashbuckle.AspNetCore" Version="6.5.0" />
  </ItemGroup>

Add this target to the .csproj file:

<!-- Generate openapi.json on build; see
     https://github.com/domaindrivendev/Swashbuckle.AspNetCore#using-the-tool-with-the-net-core-30-sdk-or-later -->
<Target Name="OpenAPI" AfterTargets="Build" Condition="$(Configuration)=='Debug'">
    <Exec Command="dotnet swagger tofile --output openapi.json $(TargetPath) v1" WorkingDirectory="$(TargetDir)" />
</Target>


In Program.cs, add the OpenApi services:
builder.Services.AddEndpointsApiExplorer()
                .AddSwaggerGen();
and append .WithOpenApi() to the MapGroup() statement:
var todosApi = app.MapGroup("/todos").WithOpenApi();
(optional) if you also want to generate the Swagger UI under the /swagger url, add:
if (app.Environment.IsDevelopment()) _ = app.UseSwagger().UseSwaggerUI();


Build the project; the build output will contain a line like:

Swagger JSON/YAML successfully written to ...\bin\Debug\net8.0\openapi.json