Entity framework .NET核心Web API在数据库上下文中更新模型不起作用
我正在编写一个名为Entity framework .NET核心Web API在数据库上下文中更新模型不起作用,entity-framework,asp.net-core-webapi,Entity Framework,Asp.net Core Webapi,我正在编写一个名为Cart.API的小服务,我应该处理我数据库中的所有添加/更新/删除请求(我使用docker,因此我在docker容器中托管一个MSSQL数据库)。现在,我陷入了方法DeleteCatalogItemAsync 这是CartController.cs的代码: using System.Collections.Generic; using System.Linq; using System.Threading.Tasks; using Cart.API.Models; using
Cart.API
的小服务,我应该处理我数据库中的所有添加/更新/删除请求(我使用docker,因此我在docker容器中托管一个MSSQL数据库)。现在,我陷入了方法DeleteCatalogItemAsync
这是CartController.cs的代码:
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Cart.API.Models;
using Cart.API.Services;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
namespace Cart.API.Controllers
{
[ApiController]
[Route("api/[controller]")]
public class CartController : ControllerBase
{
private readonly CartContext _context;
private readonly ICartService _cartService;
private readonly ICatalogService _catalogService;
public CartController(CartContext context, ICartService cartService, ICatalogService catalogService)
{
_context = context;
_cartService = cartService;
_catalogService = catalogService;
}
[HttpGet]
[Route("cart/{id}")]
public bool CartExists(int id)
{
return _context.UserCarts.Any(cart => cart.Id == id);
}
[HttpGet]
[Route("entries")]
public async Task<ActionResult<List<CartModel>>> GetAllCartAsync()
{
var cartList = await _context.UserCarts.Include(cart => cart.Items).ToListAsync(); //include needed to load Items List
if (cartList == null)
{
return NoContent();
}
return cartList;
}
[HttpGet]
[Route("entries/{id}")]
public async Task<ActionResult<CartModel>> GetCartByIdAsync(int id)
{
var cart = await _context.UserCarts.Where(b => b.Id == id).Include(m => m.Items).SingleOrDefaultAsync();
return cart ?? new CartModel(id);
}
[HttpPut]
[Route("entries")]
public async Task<ActionResult> AddCartItemAsync([FromBody] AddCartItemRequest requestItem)
{
if (requestItem == null || requestItem.Quantity == 0)
{
return BadRequest("Invalid payload");
}
//Check, if cart already exists or a new one has to be added
var cartExists = await _cartService.CheckCartExistance(requestItem.CartId);
//Get or create cart object by the requested Id
var currentCart = await _cartService.GetCartByIdAsync(requestItem.CartId);
//Get Catalog Item
var catalogItem = await _catalogService.GetCatalogItemByIdAsync(requestItem.CatalogItemId);
currentCart.Items.Add(new CartItem(catalogItem.Id, catalogItem.Name, catalogItem.Price, requestItem.Quantity));
if (!cartExists)
{
_context.UserCarts.Add(currentCart);
}
else
{
_context.UserCarts.Update(currentCart);
}
await _context.SaveChangesAsync();
return Ok(currentCart);
}
[HttpDelete]
[Route("entries/remove")]
public async Task<ActionResult> DeleteCatalogItemAsync([FromBody] DeleteCartItemRequest requestItem)
{
if (requestItem == null)
{
return BadRequest("Cannot perform action");
}
//Check if Basket exists
var basketExists = await _cartService.CheckCartExistance(requestItem.CartId);
if (basketExists)
{
//var currentCart = await _context.UserCarts.Include(model => model.Items).SingleOrDefaultAsync(model => model.Id == requestItem.CartId);
var currentCart = await _cartService.GetCartByIdAsync(requestItem.CartId);
if(currentCart != null)
{
var itemToDelete = currentCart.Items.Find(model => model.ProductId == requestItem.CatalogItemId);
currentCart.Items.Remove(itemToDelete);
//currentCart.RemoveCartItem(requestItem.CatalogItemId);
_context.UserCarts.Update(currentCart);
await _context.SaveChangesAsync();
return Ok();
}
return BadRequest("Das Item mit der ID " + requestItem.CatalogItemId + " konnte nicht gelöscht werden.");
}
return NotFound("Es existiert kein Warenkorb mit der ID " + requestItem.CartId);
}
[HttpGet]
[Route("test")]
public async Task<ActionResult> TestCall()
{
var test1 = await _catalogService.GetCatalogItemByIdAsync(1);
return Ok(test1);
}
}
}
using System.Collections.Generic;
using System.Net.Http;
using System.Threading.Tasks;
using Cart.API.Models;
using Newtonsoft.Json;
namespace Cart.API.Services
{
public class CartService : ICartService
{
private readonly HttpClient _client;
public CartService(HttpClient client)
{
_client = client;
}
public async Task<IEnumerable<CartModel>> GetAllCartsAsync()
{
var stringContent = await _client.GetStringAsync("http://cart.api/api/cart/entries");
return JsonConvert.DeserializeObject<List<CartModel>>(stringContent);
}
public async Task<CartModel> GetCartByIdAsync(int id)
{
var stringContent = await _client.GetStringAsync("http://cart.api/api/cart/entries/" + id);
var cart = !string.IsNullOrEmpty(stringContent) ? JsonConvert.DeserializeObject<CartModel>(stringContent) : null;
return cart;
}
public async Task<bool> CheckCartExistance(int cartId)
{
var stringContent = await _client.GetStringAsync("http://cart.api/api/cart/cart/" + cartId);
return JsonConvert.DeserializeObject<bool>(stringContent);
}
}
}
CartModel.cs
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using Microsoft.EntityFrameworkCore;
namespace Cart.API.Models
{
public class CartModel
{
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int Id { get; set; }
public List<CartItem> Items { get; set; }
public CartModel(int id)
{
Id = id;
Items = new List<CartItem>();
}
public bool RemoveCartItem(int id)
{
var itemToDelete = Items.Find(m => m.ProductId == id);
return Items.Remove(itemToDelete);
}
}
}
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
namespace Cart.API.Models
{
public class CartItem
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public long Id { get; set; }
public long ProductId { get; set; }
public string ProductName { get; set; }
public double ProductPrice { get; set; }
public int ProductQuantity { get; set; }
public CartItem(long productId, string productName, double productPrice, int productQuantity)
{
ProductId = productId;
ProductName = productName;
ProductPrice = productPrice;
ProductQuantity = productQuantity;
}
}
}
因此,在CartController.cs
的方法DeleteCatalogItemAsync
中,我试图提供能够删除现有CatalogItem的功能。因此,在我将CatalogItem从购物车列表中删除之前,我调用cartService来检索应该从中删除项目的购物篮。我的问题是,使用上面提供的代码,CatalogItem不会从数据库中删除,因为对currentCart对象的更改不会保存到数据库中。据我所知,currentCart对象未被跟踪,因此在将该对象保存到数据库之前,我将调用.Update方法开始跟踪该项目并将所有属性标记为已修改
var itemToDelete = currentCart.Items.Find(model => model.ProductId == requestItem.CatalogItemId);
currentCart.Items.Remove(itemToDelete);
_context.UserCarts.Update(currentCart);
await _context.SaveChangesAsync();
我按照上面的代码顺序进行了处理,并以某种方式将更改后的对象保存到dababase中,使用以下代码顺序:
var itemToDelete = currentCart.Items.Find(model => model.ProductId == requestItem.CatalogItemId);
_context.UserCarts.Update(currentCart);
currentCart.Items.Remove(itemToDelete);
await _context.SaveChangesAsync();
为什么此解决方案有效,但不是第一个?下面这行代码将实体的
currentCart
实例附加到DBContext,开始跟踪实体,并将实体状态设置为“已修改”
_context.UserCarts.Update(currentCart);
codet的下一行currentCart.Items.Remove(itemToDelete)
将导致itemToDelete
实体状态被删除
如果你打电话
currentCart.Items.Remove(itemToDelete)调用context.UserCarts.Update(currentCart)之前的代码>代码>由于DbContext未跟踪currentCart
对象,因此itemToDelete
实体将不会标记为已删除
因此,EntityFramework无法知道在调用Save
方法时需要删除此实体
希望能有所帮助首先,感谢您的回复。读过之后,它实际上是有道理的,但是。。。如果查看AddCartItemAsync方法,也会出现同样的情况。我有一个名为currentCart的未跟踪对象,在实际调用.Update之前,我在其中添加CatalogItems。这个订单运作良好。。怎么样?我的意思是,在调用\u context.SaveChangesAsync()时,在AddCartItemAsync
方法中添加项,而不是删除,情况也是一样的
currentCart
及其所有包含购物车项目的状态根据购物车的存在进行修改或添加。在这种情况下,EF框架可以确定如何处理Cart和CartItem实体。要删除实体,必须首先对其进行跟踪,然后将其状态更改为“已删除”