Nugets

• Microsoft.AspNetCore.Mvc.NewtonsoftJson
• Microsoft.AspNetCore.Mvc.Versioning.ApiExplorer
• Microsoft.Data.SqlClient
• Microsoft.Extensions.Http
• Newtonsoft.Json
• Swashbuckle.AspNetCore

Setting up Swagger and API Explorer

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc.ApiExplorer;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Options;
using Swashbuckle.AspNetCore.SwaggerGen;
using System.Net;

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        // AddNewtonsoftJson is optional
        services.AddControllers().AddNewtonsoftJson();

        services.AddApiVersioning(options =>
        {
            // reporting api versions will return the headers "api-supported-versions" and "api-deprecated-versions"
            options.ReportApiVersions = false;
            options.AssumeDefaultVersionWhenUnspecified = true;
            options.DefaultApiVersion = new Microsoft.AspNetCore.Mvc.ApiVersion(1, 0);
        });

        services.AddVersionedApiExplorer(options =>
        {
            // add the versioned api explorer, which also adds IApiVersionDescriptionProvider service
            // note: the specified format code will format the version as "'v'major[.minor][-status]"
            options.GroupNameFormat = "'v'VVV";

            // note: this option is only necessary when versioning by url segment. the SubstitutionFormat
            // can also be used to control the format of the API version in route templates
            options.SubstituteApiVersionInUrl = true;
        });
        services.AddTransient<IConfigureOptions<SwaggerGenOptions>, ConfigureSwaggerOptions>();
        services.AddSwaggerGen();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IApiVersionDescriptionProvider provider)
    {
        ServicePointManager.Expect100Continue = true;
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls13;
        ServicePointManager.DefaultConnectionLimit = 24;

        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseSwagger();
        app.UseSwaggerUI(
            options =>
            {
                foreach (var description in provider.ApiVersionDescriptions)
                {
                    options.SwaggerEndpoint(
                        $"/swagger/{description.GroupName}/swagger.json",
                        description.GroupName.ToUpperInvariant());
                }
            });

        app.UseRouting();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
        });
    }
}

ApiController

    [ApiController]
    [Route("api/[controller]")]
    public class ProductController : ControllerBase
    {
        [HttpGet]
        [Route("{id}")]
        public JsonResult Get(string id)
        {
            ...
        }
    }