// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers();
    // 資料庫配置
    var connection = @"Server=.\SQLExpress;Database=TodoDB;Trusted_Connection=True;ConnectRetryCount=0";
    services.AddDbContext<TodoDBContext>(options => options.UseSqlServer(connection));
    
    // 啟用API版控功能
    services.AddApiVersioning();

}

using System.Collections.Generic;
using Microsoft.AspNetCore.Mvc;

namespace TodoAPI.Controllers.V1
{
    [ApiVersion("1.0")]
    [Route("api/v{version:apiVersion}/[controller]")]
    [ApiController]
    public class VersionController : ControllerBase
    {
        [HttpGet]
        public IEnumerable<string> Get()
        {
            return new string[] { "api v1" };
        }
    }
}

using System.Collections.Generic;
using Microsoft.AspNetCore.Mvc;

namespace TodoAPI.Controllers.V2
{
    [ApiVersion("2.0")]
    [Route("api/v{version:apiVersion}/[controller]")]
    [ApiController]
    public class VersionController : ControllerBase
    {
        [HttpGet]
        public IEnumerable<string> Get()
        {
            return new string[] { "api v2" };
        }
    }
}

namespace TodoAPI.Controllers.V1 

namespace TodoAPI.Controllers.V2

[ApiVersion("1.0")]

[ApiVersion("2.0")]

Scaffold-DbContext "Server=.\SQLExpress;Database=TodoDB;Trusted_Connection=True;" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models

// This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllers();
        // 資料庫配置
        var connection = @"Server=.\SQLExpress;Database=TodoDB;Trusted_Connection=True;ConnectRetryCount=0";
        services.AddDbContext<TodoDBContext>(options => options.UseSqlServer(connection));
    }

using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using TodoAPI.Models;

namespace TodoAPI.Controllers
{

    [Route("api/[controller]")]
    [ApiController]
    public class TodoController : ControllerBase
    {
        private readonly TodoDBContext _context;
        public TodoController(TodoDBContext context)
        {
            _context = context;
        }
        [HttpGet]
        public async Task<ActionResult<IEnumerable<Todo>>> GetTodos()
        {
            return await _context.Todos.Where(x=>x.IsDeleted != 1).ToListAsync();
        }

        [HttpGet("{id}")]
        public async Task<ActionResult<Todo>> GetTodo(int id)
        {
            var obj = await _context.Todos.FindAsync(id);

            if (obj.IsDeleted == 1)
            {
                return NotFound();
            }

            return obj;
        }

        [HttpPut("{id}")]
        public async Task<ActionResult<Todo>> PutTodo(int id, Todo newObj)
        {
            if (id != newObj.Id)
            {
                return BadRequest();
            }

            var obj = await _context.Todos.FindAsync(id);

            if(obj.IsDeleted == 1)
            {
                return NotFound();
            }

            obj.IsComplete = newObj.IsComplete;
            obj.Name = newObj.Name;

            try
            {
                await _context.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!TodoExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return obj;
        }

        [HttpPost]
        public async Task<ActionResult<Todo>> PostTodo(Todo newObj)
        {
            var obj = new Todo
            {
                Name = newObj.Name,
                IsComplete = 0,
                IsDeleted = 0
            };
            _context.Todos.Add(obj); 
            await _context.SaveChangesAsync();

            return CreatedAtAction(nameof(GetTodo), new { id = obj.Id }, obj);
        }
        [HttpDelete("{id}")]
        public async Task<ActionResult<Todo>> DeleteTodo(int id)
        {
            var obj = await _context.Todos.FindAsync(id);
            obj.IsDeleted = 1;

            if (obj == null)
            {
                return NotFound();
            }
            try
            {
                await _context.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!TodoExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return obj;
        }

        private bool TodoExists(int id)
        {
            return _context.Todos.Any(e => e.Id == id);
        }
    }
}

using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using MVC_With_API.Models;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;

namespace MVC_With_API.Controllers
{
    public class HomeController : Controller
    {
        private readonly ILogger<HomeController> _logger;

        public HomeController(ILogger<HomeController> logger)
        {
            _logger = logger;
        }

        public IActionResult Index()
        {
            return View();
        }

        public IActionResult Privacy()
        {
            return View();
        }

        [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
        public IActionResult Error()
        {
            return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
        }

        [HttpPost]
        public JsonResult getSum(int num)
        {
            int sum = 0;
            for(int i = 0; i < num; i++)
            {
                sum += i;
            }
            return Json(new { result = sum });
        }
    }
}

@{
    ViewData["Title"] = "Home Page";
}

<div class="text-center">
    <h1 class="display-4">Welcome</h1>
    <p>Learn about <a href="https://docs.microsoft.com/aspnet/core">building Web apps with ASP.NET Core</a>.</p>
</div>

<div id="result"></div>

@section Scripts{
    <script type="text/javascript">
    $.post("Home/getSum",
        {
            num: "10",
        },
        function (data, status) {
            $('#result').html(data.result)
        });
    </script>
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;

namespace ListExample
{
    public class PaginatedList<T> : List<T>
    {
        public int PageIndex { get; private set; }
        public int TotalPages { get; private set; }

        public PaginatedList(List<T> items, int count, int pageIndex, int pageSize)
        {
            PageIndex = pageIndex;
            TotalPages = (int)Math.Ceiling(count / (double)pageSize);

            this.AddRange(items);
        }

        public bool HasPreviousPage
        {
            get
            {
                return (PageIndex > 1);
            }
        }

        public bool HasNextPage
        {
            get
            {
                return (PageIndex < TotalPages);
            }
        }

        public static async Task<PaginatedList<T>> CreateAsync(IQueryable<T> source, int pageIndex, int pageSize)
        {
            var count = await source.CountAsync();
            var items = await source.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToListAsync();
            return new PaginatedList<T>(items, count, pageIndex, pageSize);
        }
    }
}

using System;
using System.ComponentModel.DataAnnotations;
namespace ListExample.Models.ViewModels
{
    public class OrderIndexViewModel
    {
        [Display(Name = "訂單編號")]

        public string Number { get; set; }
        [Display(Name = "寄送日期")]

        public DateTime ShippingDate { get; set; }
        [Display(Name = "寄送地址")]

        public string ShippingAddress { get; set; }
        [Display(Name = "客戶簽收")]

        public string CustomerSignature { get; set; }
        [Display(Name = "客戶編號")]

        public string CustomerNumber { get; set; }
        [Display(Name = "總額")]

        public decimal Total { get; set; }
        [Display(Name = "客戶名稱")]

        public string CustomerName { get; set; }
        [Display(Name = "客戶電話")]

        public string CustomerTel { get; set; }

    }
}

using ListExample.Models;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using System;
using System.Threading.Tasks;
using System.Linq;
using ListExample.Models.ViewModels;

namespace ListExample.Controllers
{
    public class OrderController : Controller
    {

        private readonly OrdersContext _context;

        public OrderController(OrdersContext context)
        {
            _context = context;
        }
        public async Task<IActionResult> Index(
      string sortOrder,
      string currentFilterCustomer,
      string currentFilterNumber,
      string searchStringCustomer,
      string searchStringNumber,
      int? goToPageNumber,
      int pageSize,
      int? pageNumber)
        {
            // 1.搜尋邏輯
            var query = from a in _context.Orders
                        join b in _context.Customers on a.CustomerNumber equals b.Number
                        into result1
                        from ab in result1.DefaultIfEmpty()
                        select new OrderIndexViewModel
                        {
                            Number = a.Number,
                            ShippingAddress = a.ShippingAddress,
                            ShippingDate = a.ShippingDate,
                            CustomerSignature = a.CustomerSignature,
                            Total = a.Total,
                            CustomerNumber = a.CustomerNumber,
                            CustomerName = ab.Name,
                            CustomerTel = ab.Tel
                        };

            // 2.條件過濾
            if (searchStringCustomer != null || searchStringNumber != null)
            {
                pageNumber = 1;
            }
            else
            {
                searchStringCustomer = currentFilterCustomer;
                searchStringNumber = currentFilterNumber;
            }

            ViewData["CurrentFilterCustomer"] = searchStringCustomer;
            ViewData["CurrentFilterNumber"] = searchStringNumber;

            if (!String.IsNullOrEmpty(searchStringCustomer))
            {
                query = query.Where(s => s.CustomerName.Contains(searchStringCustomer));
            }
            if (!String.IsNullOrEmpty(searchStringNumber))
            {
                query = query.Where(s => s.Number.Contains(searchStringNumber));
            }

            // 3.排序依據
            ViewData["CurrentSort"] = sortOrder;

            switch (sortOrder)
            {
                case "1":
                    query = query.OrderByDescending(s => s.ShippingDate);
                    break;
                case "2":
                    query = query.OrderBy(s => s.ShippingDate);
                    break;
                case "3":
                    query = query.OrderByDescending(s => s.Total);
                    break;
                case "4":
                    query = query.OrderBy(s => s.Total);
                    break;
                default:
                    query = query.OrderByDescending(s => s.ShippingDate);
                    break;
            }

            // 4.前往頁數
            if (goToPageNumber != null)
            {
                pageNumber = goToPageNumber;
            }

            // 5.每頁筆數
            if (pageSize == 0)
            {
                pageSize = 10;
            }
            ViewData["pageSize"] = pageSize;
            
            // 6.返回結果
            return View(await PaginatedList<OrderIndexViewModel>.CreateAsync(query.AsNoTracking(), pageNumber ?? 1, pageSize));
        }

    }
}

@model PaginatedList<ListExample.Models.ViewModels.OrderIndexViewModel>
@*
    For more information on enabling MVC for empty projects, visit https://go.microsoft.com/fwlink/?LinkID=397860
*@
@{
}
<h1>Order</h1>

<form asp-action="Index" class="mt-3" id="form_search">
    <div class="row">
        <div class="col-sm col-md-6 col-lg-3 col-xl-3">
            <label class="custom-label">客戶名稱</label>
            <div class="form-group form-row">
                <div class="col">
                    <input id="input_customer" type="text" class="form-control mr-2" name="searchStringCustomer" value="@ViewData["CurrentFilterCustomer"]" />
                </div>
            </div>
        </div>
        <div class="col-sm col-md-6 col-lg-3 col-xl-3">
            <label class="custom-label">訂單編號</label>
            <div class="form-group form-row">
                <div class="col">
                    <input id="input_number" type="text" class="form-control mr-2" name="searchStringNumber" value="@ViewData["CurrentFilterNumber"]" />
                </div>
            </div>
        </div>
    </div>
    <div class="text-right">
        <button type="submit" class="btn btn-secondary mb-2">查詢資料</button>
        <button class="btn btn-outline-secondary mb-2" onclick="clearSearch();">清空查詢</button>
    </div>
    <hr class="mt-0">
    <div class="d-flex justify-content-end">
        <div class="col-2 px-0">
            <div class="form-group">
                <select class="form-control" name="sortOrder" onchange="this.form.submit()">
                    <option value="0" selected="@((string)ViewData["CurrentSort"] == "0")">預設排序</option>
                    <option value="1" selected="@((string)ViewData["CurrentSort"] == "1")">出貨日期 高→低</option>
                    <option value="2" selected="@((string)ViewData["CurrentSort"] == "2")">出貨日期 低→高</option>
                    <option value="3" selected="@((string)ViewData["CurrentSort"] == "3")">訂單總額 高→低</option>
                    <option value="4" selected="@((string)ViewData["CurrentSort"] == "4")">訂單總額 低→高</option>
                </select>
            </div>
        </div>
    </div>


    <div class="table-responsive">

        <table class="table table-bordered">
            <thead>
                <tr>
                    <th>
                        訂單編號
                    </th>
                    <th>
                        出貨日期
                    </th>
                    <th>
                        寄送地址
                    </th>
                    <th>
                        客戶編號
                    </th>
                    <th>
                        客戶名稱
                    </th>
                    <th>
                        客戶電話
                    </th>
                    <th>
                        客戶簽收人
                    </th>
                    <th>
                        訂單總額
                    </th>
                </tr>
            </thead>
            <tbody>
                @foreach (var item in Model)
                {
                    <tr>
                        <td>
                            @Html.DisplayFor(modelItem => item.Number)
                        </td>

                        <td>
                            @Convert.ToDateTime(item.ShippingDate).ToString("yyyy-MM-dd")
                        </td>
                        <td>
                            @Html.DisplayFor(modelItem => item.ShippingAddress)
                        </td>
                        <td>
                            @Html.DisplayFor(modelItem => item.CustomerNumber)
                        </td>
                        <td>
                            @Html.DisplayFor(modelItem => item.CustomerName)
                        </td>
                        <td>
                            @Html.DisplayFor(modelItem => item.CustomerTel)
                        </td>
                        <td>
                            @if (item.CustomerSignature != "" && item.CustomerSignature != null)
                            {
                                @Html.DisplayFor(modelItem => item.CustomerSignature)
                            }
                            else
                            {
                                <span>-</span>
                            }
                        </td>
                        <td>
                            @Html.DisplayFor(modelItem => item.Total)
                        </td>
                    </tr>
                }
            </tbody>
        </table>
    </div>
    @{
        var prevDisabled = !Model.HasPreviousPage ? "disabled" : "";
        var nextDisabled = !Model.HasNextPage ? "disabled" : "";
    }

    <div class="list-pagination mt-3">
        <div class="form-inline text-center">
            <div class="mx-auto">
                每頁
                <select class="custom-select" name="pageSize" onchange="changePageSize()">
                    <option value="5" selected="@((int)ViewData["pageSize"]==5)">5</option>
                    <option value="10" selected="@((int)ViewData["pageSize"]==10)">10</option>
                    <option value="30" selected="@((int)ViewData["pageSize"]==30)">30</option>
                    <option value="50" selected="@((int)ViewData["pageSize"]==50)">50</option>
                </select>，第 <span>@(Model.TotalPages < Model.PageIndex ? 0 : Model.PageIndex) / @Model.TotalPages</span> 頁，共 <span>@Model.TotalPages</span> 頁，
                <a asp-action="Index"
                    asp-route-sortOrder="@ViewData["CurrentSort"]"
                    asp-route-pageNumber="@(Model.PageIndex - 1)"
                    asp-route-currentFilterNumber="@ViewData["CurrentFilterNumber"]"
                    asp-route-CurrentFilterCustomer="@ViewData["CurrentFilterCustomer"]"
                    asp-route-pageSize="@ViewData["PageSize"]"
                    class="btn btn-outline-secondary btn-sm @prevDisabled">
                    上一頁
                </a>｜跳至第
                <select id="select_goToPage" class="custom-select" name="goToPageNumber" onchange="goToPage();">
                    <option>
                        選擇
                    </option>
                    @for (var i = 1; i <= Model.TotalPages; i++)
                    {
                        <option value="@i" selected="@(Model.PageIndex == i)">
                            @i
                        </option>
                    }
                </select>
                頁｜
                <a asp-action="Index"
                   asp-route-sortOrder="@ViewData["CurrentSort"]"
                   asp-route-pageNumber="@(Model.PageIndex + 1)"
                   asp-route-currentFilterNumber="@ViewData["CurrentFilterNumber"]"
                   asp-route-CurrentFilterCustomer="@ViewData["CurrentFilterCustomer"]"
                   asp-route-pageSize="@ViewData["PageSize"]"
                   class="btn btn-outline-secondary btn-sm @nextDisabled">
                    下一頁
                </a>

            </div>
        </div>
    </div>
</form>


@section Scripts{
    <script type="text/javascript">
        function clearSearch() {
            $('#input_customer').val('')
            $('#input_number').val('')
            $('#form_search').submit()
        }
        function goToPage() {
            $('#form_search').submit()
        }
        function changePageSize() {
            $('#form_search').submit()
        }
    </script>
}

using Dapper;
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Threading.Tasks;

namespace DapperExample.Dapper
{
    public class DataControl : IDisposable
    {
        private IDbConnection db = null;
        private string _connectStr;

        //建構子初始化連線字串/DB連接
        public DataControl()
        {
            // 自行替換資料庫連結字串
            string connectionStr = @"Server=.\SQLExpress;Database=Orders;Trusted_Connection=True;ConnectRetryCount=0";
            _connectStr = connectionStr;
            db = new SqlConnection(_connectStr);
        }

        //共用查詢方法
        public IEnumerable<T> Query<T>(string sql, object param)
        {
            return db.Query<T>(sql, param).ToList();
        }

        //共用新增刪除修改方法
        public int Execute(string sql, object param)
        {
            return db.Execute(sql, param);
        }

        //釋放連接
        public void Dispose()
        {
            db.Dispose();
        }
    }
}

using System.ComponentModel.DataAnnotations;
namespace DapperExample.Models
{
    public class Customer
    {
        [Display(Name = "編號")]
        public string Number { get; set; }
       
        [Display(Name = "名子")]
        [Required(ErrorMessage = "名字不可為空")]
        public string Name { get; set; }
       
        [Display(Name = "電話")]
        public string Tel { get; set; }
    }
}

using DapperExample.Dapper;
using DapperExample.Models;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;

namespace DapperExample.Controllers
{
    public class HomeController : Controller
    {
        private readonly ILogger<HomeController> _logger;

        public HomeController(ILogger<HomeController> logger)
        {
            _logger = logger;
        }

        public IActionResult Index()
        {
            Customer customer;
            // 使用using，區塊結束後會自動執行Dispose
            using (DataControl dc = new DataControl())
            {
                string number = "U001";
                string sql = @"SELECT * FROM Customers WHERE number = @number";
                var result = dc.Query<Customer>(sql, new { number });//執行DataControl的Query方法
                customer = result.First();
            }
            return View(customer);
        }

        public IActionResult Privacy()
        {
            return View();
        }

        [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
        public IActionResult Error()
        {
            return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
        }
    }
}

@model DapperExample.Models.Customer;
@{
    ViewData["Title"] = "Home Page";
}

<div class="text-center">
    <h1 class="display-4">Welcome</h1>
    <p>Learn about <a href="https://docs.microsoft.com/aspnet/core">building Web apps with ASP.NET Core</a>.</p>
</div>
<ul>
    <li>@Model.Number</li>
    <li>@Model.Name</li>
    <li>@Model.Tel</li>
</ul>

//　產品
Product[] products = new Product[] {
  new Product { Id = 1 ,Name = "PS4",Price =11000   } ,
  new Product { Id = 2 ,Name = "PS5",Price =15000   },
  new Product { Id = 3 ,Name = "Switch",Price=9900 },
  new Product{ Id= 4 ,Name="XBOX Series X",Price=15000   }
};

//　分類
ProductType[] productTypes = new ProductType[] {
  new ProductType {Id = 1 ,Name = "Game"} ,
  new ProductType { Id = 2 ,Name = "nintendo" } ,
  new ProductType { Id =3 ,Name = "Sony" }
};


//　產品與分類關系表
Product_ProductTypeRelationship[] product_ProductTypeRelationships = new Product_ProductTypeRelationship[] {
  new Product_ProductTypeRelationship {
      ProductID = 1 ,ProductTypeID = 1
  } ,
  new Product_ProductTypeRelationship {
      ProductID = 1 ,ProductTypeID = 3
  } ,
  new Product_ProductTypeRelationship {
      ProductID = 2 ,ProductTypeID = 1
  } ,
  new Product_ProductTypeRelationship {
      ProductID = 2 ,ProductTypeID = 3
  },
  new Product_ProductTypeRelationship {
      ProductID = 3 ,ProductTypeID = 1
  } ,
  new Product_ProductTypeRelationship {
      ProductID = 3 ,ProductTypeID = 2
  }
};

public void linqInnerJoinExample()
{
    var query =
        from product in products
        join product_ProductTypeRelationship in product_ProductTypeRelationships on product.Id equals product_ProductTypeRelationship.ProductID
        join productType in productTypes on product_ProductTypeRelationship.ProductTypeID equals productType.Id
        select new
        {
            product.Id,
            product.Name,
            product.Price,
            productTypeName = productType.Name
        };
    var result = query.ToList();
}

public void linqLeftJoinExample()
{
    // product 跟 product_ProductTypeRelationship 先left join 
    var query1 =
        from product in products
        join product_ProductTypeRelationship in product_ProductTypeRelationships on product.Id equals product_ProductTypeRelationship.ProductID
        into tmp
        from product_ProductTypeRelationship in tmp.DefaultIfEmpty()
        select new
        {
            product.Id,
            product.Name,
            product.Price,
            ProductTypeID = product_ProductTypeRelationship?.ProductTypeID
        };

    // query1結果再跟 productTypes left join 
    var query2 =
        from q in query1
        join productType in productTypes on q.ProductTypeID equals productType.Id
        into tmp
        from product_ProductTypeRelationship in tmp.DefaultIfEmpty()
        select new
        {
            q.Id,
            q.Name,
            q.Price,
            ProductName = product_ProductTypeRelationship?.Name
        };
    var result = query2.ToList();
}

public void linqLeftJoinExample2()
{
    var query =
        from a in products
        join b in product_ProductTypeRelationships on a.Id equals b.ProductID
        into result1
        from ab in result1.DefaultIfEmpty()
        join c in productTypes on ab?.ProductTypeID equals c.Id
        into result2
        from abc in result2.DefaultIfEmpty()
        select new{
            a.Id,
            a.Name,
            a.Price,
            ProductName = abc?.Name
        } ;
    var result = query.ToList();
}

public void linqLeftJoinExample3()
{

    var p = (from a in products
                select new ProductViewModel
                {
                    Id = a.Id,
                    Name = a.Name,
                    Price = a.Price,
                }).ToList();

    foreach (var item in p)
    {
        var productTypeIDs = from a in product_ProductTypeRelationships
                                where a.ProductID == item.Id
                                select a.ProductTypeID;

        var productTypeData = from a in productTypeIDs
                                join b in productTypes on a equals b.Id
                                select new ProductType
                                {
                                    Id = b.Id,
                                    Name = b.Name
                                };
        item.ProductTypes = new List<ProductType>();
        foreach (var x in productTypeData)
        {
            item.ProductTypes.Add(x);
        }
    }
    var result = p;
    string jsonData = JsonConvert.SerializeObject(result);
    System.Diagnostics.Debug.WriteLine(jsonData);
}

[
  {
    "Id": 1,
    "Name": "PS4",
    "Price": 11000,
    "ProductTypes": [
      {
        "Id": 1,
        "Name": "Game"
      },
      {
        "Id": 3,
        "Name": "Sony"
      }
    ]
  },
  {
    "Id": 2,
    "Name": "PS5",
    "Price": 15000,
    "ProductTypes": [
      {
        "Id": 1,
        "Name": "Game"
      },
      {
        "Id": 3,
        "Name": "Sony"
      }
    ]
  },
  {
    "Id": 3,
    "Name": "Switch",
    "Price": 9900,
    "ProductTypes": [
      {
        "Id": 1,
        "Name": "Game"
      },
      {
        "Id": 2,
        "Name": "nintendo"
      }
    ]
  },
  {
    "Id": 4,
    "Name": "XBOX Series X",
    "Price": 15000,
    "ProductTypes": []
  }
]

public IActionResult Index()
{
    // Specify the data source.
    int[] scores = new int[] { 97, 92, 81, 60 };

    // Define the query expression.
    IEnumerable<int> scoreQuery =
        from score in scores
        where score > 80
        select score;

    // Execute the query.
    foreach (int i in scoreQuery)
    {
        Console.Write(i + " ");
    }
    return View();
}