We will discuss minimal APIs in .NET Core 6, their purpose, and step-by-step implementation.

Minimal APIs Implementation using .NET Core 6

Step 1
Create a new .NET Core Web API

Step 2
Configure your project

Step 3
Provide additional information as I showed below

Step 4
Install the following NuGet packages

Project structure

Step 5
Create a Product class inside the entities folder
namespace MinimalAPIsDemo.Entities
{
    public class Product
    {
        public int ProductId { get; set; }
        public string ProductName { get; set; }
        public string ProductDescription { get; set; }
        public int ProductPrice { get; set; }
        public int ProductStock { get; set; }
    }
}

Step 6
Next, create DbContextClass inside the Data folder
using Microsoft.EntityFrameworkCore;
using MinimalAPIsDemo.Entities;

namespace MinimalAPIsDemo.Data
{
    public class DbContextClass : DbContext
    {
        protected readonly IConfiguration Configuration;

        public DbContextClass(IConfiguration configuration)
        {
            Configuration = configuration;
        }
        protected override void OnConfiguring(DbContextOptionsBuilder options)
        {
            options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection"));
        }

        public DbSet<Product> Product { get; set; }
    }
}

Step 7
Register the Db Context service in the DI container inside the Program class which is the entry point of our application
// Add services to the container.
builder.Services.AddDbContext<DbContextClass>();

Step 8
Add database connection string inside the app settings file
{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "DefaultConnection": "Data Source=DESKTOP;Initial Catalog=MinimalAPIDemo;User Id=sa;Password=database;"
  }
}

Step 9
Later on, add different API endpoints inside the Program class with the help of Map and specified routing pattern as I showed below
using Microsoft.EntityFrameworkCore;
using MinimalAPIsDemo.Data;
using MinimalAPIsDemo.Entities;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddDbContext<DbContextClass>();

// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

//get the list of product
app.MapGet("/productlist", async (DbContextClass dbContext) =>
{
    var products = await dbContext.Product.ToListAsync();
    if (products == null)
    {
        return Results.NoContent();
    }
    return Results.Ok(products);
});

//get product by id
app.MapGet("/getproductbyid", async (int id, DbContextClass dbContext) =>
{
    var product = await dbContext.Product.FindAsync(id);
    if (product == null)
    {
        return Results.NotFound();
    }
    return Results.Ok(product);
});

//create a new product
app.MapPost("/createproduct", async (Product product, DbContextClass dbContext) =>
{
    var result = dbContext.Product.Add(product);
    await dbContext.SaveChangesAsync();
    return Results.Ok(result.Entity);
});

//update the product
app.MapPut("/updateproduct", async (Product product, DbContextClass dbContext) =>
{
    var productDetail = await dbContext.Product.FindAsync(product.ProductId);
    if (product == null)
    {
        return Results.NotFound();
    }
    productDetail.ProductName = product.ProductName;
    productDetail.ProductDescription = product.ProductDescription;
    productDetail.ProductPrice = product.ProductPrice;
    productDetail.ProductStock = product.ProductStock;

    await dbContext.SaveChangesAsync();
    return Results.Ok(productDetail);
});

//delete the product by id
app.MapDelete("/deleteproduct/{id}", async (int id, DbContextClass dbContext) =>
{
    var product = await dbContext.Product.FindAsync(id);
    if (product == null)
    {
        return Results.NoContent();
    }
    dbContext.Product.Remove(product);
    await dbContext.SaveChangesAsync();
    return Results.Ok();
});

app.Run();

Step 10
Run the following entity framework command to create migration and update the database
add-migration "initial"
update-database

Step 11
Finally, run your application