.Net 9 webapi template with minimal api + Swagger + Swashbuckle

README.md

To recreate:

1. dotnet new webapi
2. Add packages Swashbuckle.AspNetCore and Swashbuckle.AspNetCore.Annotations to your csproj file.
3. Change the Program.cs

builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen(options =>
{
    options.SwaggerDoc("v1", new OpenApiInfo { Title = "WebApi9", Version = "v1" });
});
builder.Services.AddMvcCore().AddApiExplorer();

and

app.MapSwagger();
app.UseSwaggerUI(c =>
{
    c.SwaggerEndpoint("/swagger/v1/swagger.json", "WebApi9 v1");
    c.RoutePrefix = string.Empty; // Set Swagger UI at the app's root
});    

Program.cs

using Microsoft.OpenApi.Models;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
// Learn more about configuring OpenAPI at https://aka.ms/aspnet/openapi
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen(options =>
{
    options.SwaggerDoc("v1", new OpenApiInfo { Title = "Your SwaggerUI Title Here", Version = "v1", });
});
builder.Services.AddMvcCore().AddApiExplorer();
var app = builder.Build();

app.UseSwagger(c =>
{
    c.PreSerializeFilters.Add((swaggerDoc, httpReq) =>
    {
        swaggerDoc.Servers = new List<OpenApiServer>
        {
            new OpenApiServer { Url = $"{httpReq.Scheme}://{httpReq.Host.Value}" }
        };
    });
});
app.UseSwaggerUI(c =>
{
    c.RoutePrefix = string.Empty; // Set Swagger UI at the app's root
});

app.UseHttpsRedirection();

var summaries = new[]
{
    "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
};

app.MapGet("/weatherforecast", () =>
{
    var forecast =  Enumerable.Range(1, 5).Select(index =>
        new WeatherForecast
        (
            DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
            Random.Shared.Next(-20, 55),
            summaries[Random.Shared.Next(summaries.Length)]
        ))
        .ToArray();
    return forecast;
})
.WithName("GetWeatherForecast");

app.Run();

record WeatherForecast(DateOnly Date, int TemperatureC, string? Summary)
{
    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
}

WebApi.csproj

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

  <PropertyGroup>
    <TargetFramework>net9.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="9.0.3" />
    <PackageReference Include="Swashbuckle.AspNetCore" Version="9.0.1" />
    <PackageReference Include="Swashbuckle.AspNetCore.Annotations" Version="9.0.1" />
  </ItemGroup>

</Project>