📅 Day 5：訂單提交與支付模擬

? 今日目標：

• 創建 Order 和 OrderItem 模型
• 實現從購物車生成訂單的功能
• 模擬支付流程（成功/失敗頁面）
• 添加訂單狀態跟蹤（如“待付款”、“已發貨”等）
• 提交 Git 版本記錄進度

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🧩 功能概覽

頁面	功能
/Checkout/Index.cshtml	確認訂單信息
/Checkout/Success.cshtml	支付成功頁面
/Checkout/Failed.cshtml	支付失敗頁面
/Orders/Index.cshtml	我的訂單列表
數據庫模型	Order, OrderItem

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🛠? 知識點預覽

技術	內容
數據模型	Order 表示訂單，OrderItem 表示訂單中的商品
購物車轉訂單	將 Session 中的購物車數據保存為訂單
支付模擬	使用按鈕或自動跳轉模擬支付結果
用戶身份驗證	只有登錄用戶才能下單
UI 設計	Bootstrap + Razor Pages 構建訂單確認頁

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🧱 第一步：創建訂單相關模型

在 Models 文件夾中創建以下兩個類：

? Order.cs

using System.ComponentModel.DataAnnotations;namespace ECommercePlatform.Models
{public enum OrderStatus{Pending,Paid,Shipped,Completed,Cancelled}public class Order{public int Id { get; set; }[Required]public string UserId { get; set; } = string.Empty;public DateTime OrderDate { get; set; } = DateTime.Now;public decimal TotalAmount { get; set; }public OrderStatus Status { get; set; } = OrderStatus.Pending;public List<OrderItem> Items { get; set; } = new();}
}

? OrderItem.cs

namespace ECommercePlatform.Models
{public class OrderItem{public int Id { get; set; }public int ProductId { get; set; }public string ProductName { get; set; } = string.Empty;public decimal Price { get; set; }public int Quantity { get; set; }public decimal TotalPrice => Price * Quantity;public int OrderId { get; set; }public Order Order { get; set; } = null!;}
}

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🧰 第二步：更新數據庫上下文

打開 ApplicationDbContext.cs 并添加以下代碼：

public DbSet<Order> Orders { get; set; }
public DbSet<OrderItem> OrderItems { get; set; }

然后執行遷移命令：

dotnet ef migrations add AddOrderAndOrderItem
dotnet ef database update

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🛒 第三步：創建訂單服務邏輯

? 創建 Services/IOrderService.cs

using ECommercePlatform.Models;public interface IOrderService
{Task<int> CreateOrderFromCart(string userId, IList<CartItem> cartItems);Task<IList<Order>> GetOrdersByUser(string userId);Task<Order?> GetOrderById(int id, string userId);
}

? 創建 Services/OrderService.cs

using Microsoft.AspNetCore.Identity;
using ECommercePlatform.Models;
using ECommercePlatform.Services;public class OrderService : IOrderService
{private readonly ApplicationDbContext _context;private readonly UserManager<IdentityUser> _userManager;public OrderService(ApplicationDbContext context, UserManager<IdentityUser> userManager){_context = context;_userManager = userManager;}public async Task<int> CreateOrderFromCart(string userId, IList<CartItem> cartItems){if (cartItems.Count == 0) throw new ArgumentException("購物車為空");var order = new Order{UserId = userId,OrderDate = DateTime.Now,TotalAmount = cartItems.Sum(i => i.TotalPrice),Items = cartItems.Select(i => new OrderItem{ProductId = i.ProductId,ProductName = i.Name,Price = i.Price,Quantity = i.Quantity}).ToList()};_context.Orders.Add(order);await _context.SaveChangesAsync();return order.Id;}public async Task<IList<Order>> GetOrdersByUser(string userId){return await _context.Orders.Include(o => o.Items).Where(o => o.UserId == userId).OrderByDescending(o => o.OrderDate).ToListAsync();}public async Task<Order?> GetOrderById(int id, string userId){return await _context.Orders.Include(o => o.Items).FirstOrDefaultAsync(o => o.Id == id && o.UserId == userId);}
}

注冊服務到 Program.cs：

builder.Services.AddScoped<IOrderService, OrderService>();

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📋 第四步：創建訂單確認頁面（Checkout/Index）

? Checkout/Index.cshtml.cs

using Microsoft.AspNetCore.Mvc.RazorPages;
using ECommercePlatform.Services;
using ECommercePlatform.Models;namespace ECommercePlatform.Pages.Checkout
{[Authorize]public class IndexModel : PageModel{private readonly IShoppingCartService _cartService;private readonly UserManager<IdentityUser> _userManager;public IndexModel(IShoppingCartService cartService, UserManager<IdentityUser> userManager){_cartService = cartService;_userManager = userManager;}public IList<CartItem> CartItems { get; set; } = new List<CartItem>();public decimal TotalPrice { get; set; }public async Task<IActionResult> OnGetAsync(){CartItems = _cartService.GetCartItems();TotalPrice = _cartService.GetTotalPrice();if (CartItems.Count == 0){return RedirectToPage("/Cart/Index");}return Page();}public async Task<IActionResult> OnPostAsync(){var user = await _userManager.GetUserAsync(User);if (user == null) return NotFound();var cartItems = _cartService.GetCartItems();if (cartItems.Count == 0) return BadRequest();// 創建訂單var orderService = HttpContext.RequestServices.GetService<IOrderService>();var orderId = await orderService.CreateOrderFromCart(user.Id, cartItems);// 清空購物車_cartService.ClearCart();return RedirectToPage("/Checkout/Success", new { id = orderId });}}
}

? Checkout/Index.cshtml

@page
@model ECommercePlatform.Pages.Checkout.IndexModel<h2>確認訂單</h2><table class="table"><thead><tr><th>名稱</th><th>單價</th><th>數量</th><th>總價</th></tr></thead><tbody>@foreach (var item in Model.CartItems){<tr><td>@item.Name</td><td>$@item.Price</td><td>@item.Quantity</td><td>$@item.TotalPrice</td></tr>}</tbody>
</table><h4>總計：$@Model.TotalPrice</h4><form method="post"><button type="submit" class="btn btn-success">立即支付</button>
</form>

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? 第五步：創建支付成功頁面（Checkout/Success）

? Success.cshtml.cs

using Microsoft.AspNetCore.Mvc.RazorPages;namespace ECommercePlatform.Pages.Checkout
{public class SuccessModel : PageModel{public void OnGet(int id){// 這里可以顯示訂單編號或詳細信息}}
}

? Success.cshtml

@page
@model ECommercePlatform.Pages.Checkout.SuccessModel<h2>? 支付成功！</h2>
<p>您的訂單已提交。訂單號：@Request.Query["id"]</p>
<a asp-page="/Orders/Index" class="btn btn-primary">查看我的訂單</a>

---

? 第六步：創建支付失敗頁面（Checkout/Failed）

? Failed.cshtml.cs

using Microsoft.AspNetCore.Mvc.RazorPages;namespace ECommercePlatform.Pages.Checkout
{public class FailedModel : PageModel{public void OnGet(){}}
}

? Failed.cshtml

@page
@model ECommercePlatform.Pages.Checkout.FailedModel<h2>? 支付失敗</h2>
<p>請返回重新嘗試支付。</p>
<a asp-page="/Cart/Index" class="btn btn-warning">返回購物車</a>

---

📦 第七步：創建我的訂單頁面（Orders/Index）

? Orders/Index.cshtml.cs

using Microsoft.AspNetCore.Mvc.RazorPages;
using ECommercePlatform.Services;
using ECommercePlatform.Models;
using Microsoft.AspNetCore.Identity;namespace ECommercePlatform.Pages.Orders
{[Authorize]public class IndexModel : PageModel{private readonly IOrderService _orderService;private readonly UserManager<IdentityUser> _userManager;public IndexModel(IOrderService orderService, UserManager<IdentityUser> userManager){_orderService = orderService;_userManager = userManager;}public IList<Order> Orders { get; set; } = new List<Order>();public async Task OnGetAsync(){var user = await _userManager.GetUserAsync(User);if (user != null){Orders = await _orderService.GetOrdersByUser(user.Id);}}}
}

? Orders/Index.cshtml

@page
@model ECommercePlatform.Pages.Orders.IndexModel<h2>我的訂單</h2>@if (Model.Orders.Count == 0)
{<p>暫無訂單。</p>
}
else
{<table class="table"><thead><tr><th>訂單號</th><th>日期</th><th>總金額</th><th>狀態</th><th>操作</th></tr></thead><tbody>@foreach (var order in Model.Orders){<tr><td>@order.Id</td><td>@order.OrderDate.ToShortDateString()</td><td>$@order.TotalAmount</td><td>@order.Status</td><td><a asp-page="/Orders/Details" asp-route-id="@order.Id" class="btn btn-info btn-sm">查看詳情</a></td></tr>}</tbody></table>
}

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📦 第八步：提交 Git 版本

git add .
git commit -m "Day5: Added order submission and payment simulation with order status tracking"

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📝 今日總結

今天你完成了：

? 創建 Order 和 OrderItem 模型
? 實現從購物車生成訂單的功能
? 模擬支付流程（成功/失敗頁面）
? 訂單狀態跟蹤（Pending、Paid、Shipped 等）
? 提交版本控制記錄

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📆 明日計劃（Day6）

我們將進入 后臺管理系統開發階段：

• 創建管理員頁面
• 實現商品管理（CRUD）
• 實現訂單管理（查看、狀態變更）
• 權限控制（僅管理員可見）