体验一下aspweb的功能和用法!!!

Program.cs

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+using Microsoft.EntityFrameworkCore;
+using SimpleTodoApiWithPg.Data;
+using SimpleTodoApiWithPg.Models;
+using Microsoft.AspNetCore.Http.HttpResults;
+using Microsoft.AspNetCore.Mvc;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// === 配置 EF Core 连接 PostgreSQL ===
+// 从配置中获取连接字符串
+var connectionString = builder.Configuration.GetConnectionString("DefaultConnection");
+
+// 添加数据库上下文服务
+builder.Services.AddDbContext<AppDbContext>(options =>
+    options.UseNpgsql(connectionString)); // 使用 Npgsql 作为 PostgreSQL 提供者
+
+var app = builder.Build();
+
+// === 应用数据库迁移 (仅在开发环境中推荐) ===
+// 在应用启动时自动应用所有挂起的数据库迁移
+using (var scope = app.Services.CreateScope())
+{
+    var dbContext = scope.ServiceProvider.GetRequiredService<AppDbContext>();
+    dbContext.Database.Migrate();
+}
+
+// === 定义 API 端点 (Endpoints) ===
+
+// GET /todos - 获取所有待办事项
+app.MapGet("/todos", async (AppDbContext dbContext) =>
+{
+    var todos = await dbContext.Todos.ToListAsync();
+    return TypedResults.Ok(todos);
+});
+
+// GET /todos/{id} - 根据 ID 获取单个待办事项
+app.MapGet("/todos/{id}", async (int id, AppDbContext dbContext) =>
+{
+    var todo = await dbContext.Todos.FindAsync(id);
+    return todo is not null
+        ? TypedResults.Ok(todo)
+        : Results.NotFound($"待办事项 (ID: {id}) 不存在。");
+});
+
+// POST /todos - 新增一个待办事项
+app.MapPost("/todos", async (Todo todo, AppDbContext dbContext) =>
+{
+    // EF Core 会自动处理 ID 的生成（如果是自增主键）
+    dbContext.Todos.Add(todo);
+    await dbContext.SaveChangesAsync(); // 保存更改到数据库
+
+    // 回传 201 Created 并提供新资源的位置
+    return Results.Created($"/todos/{todo.Id}", todo);
+});
+
+// PUT /todos/{id} - 更新指定的待办事项
+app.MapPut("/todos/{id}", async (int id, Todo inputTodo, AppDbContext dbContext) =>
+{
+    // 查找现有待办事项
+    var existingTodo = await dbContext.Todos.FindAsync(id);
+
+    if (existingTodo is null)
+    {
+        return Results.NotFound($"待办事项 (ID: {id}) 不存在。");
+    }
+
+    // 更新属性
+    existingTodo.Title = inputTodo.Title;
+    existingTodo.IsCompleted = inputTodo.IsCompleted;
+
+    await dbContext.SaveChangesAsync(); // 保存更改到数据库
+
+    return Results.NoContent(); // 回传 204 No Content 表示成功但无内容回传
+});
+
+// DELETE /todos/{id} - 删除指定的待办事项
+app.MapDelete("/todos/{id}", async (int id, AppDbContext dbContext) =>
+{
+    var todoToDelete = await dbContext.Todos.FindAsync(id);
+
+    if (todoToDelete is null)
+    {
+        return Results.NotFound($"待办事项 (ID: {id}) 不存在。");
+    }
+
+    dbContext.Todos.Remove(todoToDelete);
+    await dbContext.SaveChangesAsync(); // 保存更改到数据库
+    
+    return TypedResults.Ok($"待办事项 (ID: {id}) 已成功删除。");
+});
+
+// 运行应用程式
+app.Run();