How to OpenApi Spec + openapi-generator

This is a low code initiation to make a dotnet api with OpenApi Spec. The steps heavily rely the cli part of the openapi-generator-tool.

Generate an ASPnet Server from the spec

openapi-generator generate -i openapi.yaml -o . -g aspnetcore --additional-properties=aspnetCoreVersion=6.0

Even though it generates for dotnet v6.0, it is possible to modify the Org.OpenAPITools.csproj, field: Project.PropertyGroup.TargetFramework from net6.0 to net8.0

Adjust to make it work "out-of-the-box"

Startup.cs

Near the bottom, between

...
app.UseRouting();
app.UseEndpoints(endpoints =>
...

insert app.UseAuthorization();, like so:

...
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
...

Org.OpenAPITools.Authentication.ApiKeyRequirementHandler

Inside Org.OpenAPITools.Authentication.ApiKeyRequirementHandler, change the method: SucceedRequirementIfApiKeyPresentAndValid, so that it always hits: context.Succeed(requirement);

We have effectively disabled auth, you have to provide your own means of doing so.

Controllers

Inside: Org.OpenAPITools.Controllers.ComputerApiController we just want the examples to return json, so we remove the xml-part.

Try it

Build with the generated build command build.sh or build.bat and run it with:

dotnet run -p src/Org.OpenAPITools/Org.OpenAPITools.csproj

goto: http://localhost:8080/openapi/index.html to see the OpenApi spec ui and call curl localhost:8080/api/computer/10 to receive some json.