.NET 6 Minimal API
Watch the video here
.NET 6 comes with a new template for C# WebAPIs which is much more minimal. This exercise walks through setting up some endpoints in that template without using controllers.
Prerequisites
Loose Agenda
Set up APIs in the .NET 6 WebAPI template without controllers
Step by Step
Setup Playground
Create a directory for today’s exercise and navigate to it in a terminal instance.
Run dotnet new webapi then open the directory in Visual Studio Code.
Clean up Controllers
Delete the Controllers directory.
Delete WeatherForecast.cs.
Open Program.cs
Replace builder.Services.AddControllers(); with builder.Services.AddEndpointsApiExplorer();
Move these lines out of the if-block
app.UseSwagger();
app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "net_6_minimal_api v1"));
Remove app.UseAuthorization(); and app.MapControllers();
Add a GET endpoint
Just above app.Run(); let’s add the following code:
app.MapGet("/example", () => {
return "This is an example of a GET endpoint";
});
Run the code via dotnet run in the terminal instance and navigate to localhost:5001/swagger
Dependency Injection
To demonstrate dependency injection, let’s create a class which we can inject and call for a result.
Create a new file named DemoService.cs with the following code:
public class DemoService
{
public string NeedlesslyConsumeResources() {
return "Non-Zero Memory Consumption";
}
}
Back in Program.cs just below var builder = WebApplication.CreateBuilder(args); add the following line
builder.Services.AddScoped<DemoService>();
Now let’s add another GET endpoint with the following code:
app.MapGet("/demo", (DemoService _service) => {
return _service.NeedlesslyConsumeResources();
});
Note that dependency injection is occuring naturally through the delegate parameter.
Run the code via dotnet run in the terminal instance and navigate to localhost:5001/swagger
ActionResults
Let’s end by demonstrating ActionResults as a return type in minimal APIs
One more GET endpoint, but this one will be tempermental.
We’ll need to add an using declaration for FromQuery by adding using Microsoft.AspNetCore.Mvc;
app.MapGet("/actionresults", (DemoService _service, [FromQuery]bool acceptable) => {
if(acceptable) {
return Results.Ok(_service.NeedlesslyConsumeResources());
}
return Results.BadRequest("It's not okay to needlessly consume resources.");
});
Run the code via dotnet run in the terminal instance and navigate to localhost:5001/swagger