Question

我已经搜索了相关问题，但是找不到解决方案。我有一个asp.net核心Web应用程序，在其中选择一行并编辑记录。它在弹出窗口中显示表单，其中包含相关数据以及ID（也已隐藏）。这是实体：

public class Sender
{
    public long Id { get; set; }
    public string  Name { get; set; }
    public string Address { get; set; }
    public string ContactPerson { get; set; }
    public string ContactEmail { get; set; }
    public IEnumerable<Document> Documents { get; set; }
}

我使用存储库模式来处理数据操作：

public class DataSender : IRepositorySender
{
    private DataContext DataContext;
    public DataSender(DataContext Context)
    {
        DataContext = Context;
    }
    public IEnumerable<Sender> Senders => DataContext.Senders;
    public Sender GetSender(long SenderId)
    {
        return DataContext.Senders.Find(SenderId);
    }
    public void AddSender(Sender Sender)
    {
        DataContext.Senders.Add(Sender);
        DataContext.SaveChanges();
    }
    public void UpdateSender(Sender Sender)
    {
        DataContext.Senders.Update(Sender);
        DataContext.SaveChanges();
    }
    public void DeleteSender(Sender Sender)
    {

    }
}

这是相关的动作：

[Route("{SenderId}")]
    public IActionResult UpdateSender(long SenderId)
    {
        ViewBag.Mode = "update";
        return PartialView("Sender", SenderRepository.GetSender(SenderId));
    }
    [HttpPost("UpdateSender")]
    public IActionResult UpdateSender(Sender Sender)
    {
        SenderRepository.UpdateSender(Sender);
        return RedirectToAction(nameof(List));
    }

我在弹出窗口中获得了所需的数据，保存了更改，但是EF插入了一条新记录，而不是对其进行更新。为什么？

编辑：

这是更新视图：

@model Sender

<form asp-action=@(ViewBag.Mode == "new" ? "AddSender" : "UpdateSender") asp-controller="Sender"  method="post">
    @using (Html.DevExtreme().ValidationGroup())
    {
        @(Html.DevExtreme().Form<Sender>()
            .ID("form")
            .ColCount(1)
            .Items(items => {
            items.AddSimpleFor(m => Model.Id).Visible(false);
            items.AddSimpleFor(m => Model.Name);
            items.AddSimpleFor(m => Model.Address);
            items.AddSimpleFor(m => Model.ContactPerson);
            items.AddSimpleFor(m => Model.ContactEmail);
            items.AddGroup().Items(groupItem => groupItem.AddSimple().Template(
                @<text>
                    <div style="text-align: right">
                        @(Html.DevExtreme().Button().ID("save").Text("Mentés").Width(100).Type(ButtonType.Success).UseSubmitBehavior(true))
                        @(Html.DevExtreme().Button().ID("cancel").Text("Mégsem").Width(100).Type(ButtonType.Normal).OnClick("close_onClick"))
                    </div>

                </text>));
            })
            .LabelLocation(FormLabelLocation.Top)
            .FormData(Model)
        )
    }
</form>

编辑2： 这是调试窗口的输出。对您有用吗？我看到，EF需要一个新的ID，并将记录插入数据库中。关键点在于，为什么ID为0，为什么EF或webapp（模型绑定）无法识别实体已经具有有效的ID值。

Microsoft.EntityFrameworkCore.ChangeTracking: Debug: 'DataContext' generated temporary value '-9223372036854774805' for the 'Id' property of new 'Sender' entity.
Microsoft.EntityFrameworkCore.ChangeTracking: Debug: Context 'DataContext' started tracking 'Sender' entity with key '{Id: -9223372036854774805}'.
Microsoft.EntityFrameworkCore.ChangeTracking: Debug: DetectChanges starting for 'DataContext'.
Microsoft.EntityFrameworkCore.ChangeTracking: Debug: DetectChanges completed for 'DataContext'.
Microsoft.EntityFrameworkCore.Database.Transaction: Debug: Beginning transaction with isolation level 'Unspecified'.
Microsoft.EntityFrameworkCore.Database.Transaction: Debug: Began transaction with isolation level 'ReadCommitted'.
Microsoft.EntityFrameworkCore.Database.Command: Debug: Creating DbCommand for 'ExecuteReader'.
Microsoft.EntityFrameworkCore.Database.Command: Debug: Created DbCommand for 'ExecuteReader' (3ms).
Microsoft.EntityFrameworkCore.Database.Command: Debug: Executing DbCommand [Parameters=[@p0='Teszt cím' (Nullable = false) (Size = 4000), @p1='teszt@teszt.com' (Nullable = false) (Size = 4000), @p2='Teszt név' (Nullable = false) (Size = 4000), @p3='Teszt cég' (Nullable = false) (Size = 4000)], CommandType='Text', CommandTimeout='30']
SET NOCOUNT ON;
INSERT INTO [Senders] ([Address], [ContactEmail], [ContactPerson], [Name])
VALUES (@p0, @p1, @p2, @p3);
SELECT [Id]
FROM [Senders]
WHERE @@ROWCOUNT = 1 AND [Id] = scope_identity();
Microsoft.EntityFrameworkCore.ChangeTracking: Debug: Foreign key property 'Sender.Id' detected as changed from '-9223372036854774805' to '71' for entity with key '{Id: 71}'.
Microsoft.EntityFrameworkCore.Database.Command: Debug: A data reader was disposed.
Microsoft.EntityFrameworkCore.Database.Transaction: Debug: Committing transaction.
Microsoft.EntityFrameworkCore.Database.Transaction: Debug: Committing transaction.
Microsoft.EntityFrameworkCore.Database.Transaction: Debug: Disposing transaction.
Microsoft.EntityFrameworkCore.ChangeTracking: Debug: The 'Sender' entity with key '{Id: 71}' tracked by 'DataContext' changed from 'Added' to 'Unchanged'.

Answer 1

我看到了，没有看到完整的流程就无济于事，您可以尝试使用Debug Logger并查看更改跟踪

 services.AddDbContext<ApplicationDbContext>(options => options
              .UseLoggerFactory(MyLoggerFactory)
              .UseSqlServer(Configuration.GetConnectionString("DefaultConnection")).EnableSensitiveDataLogging());
              
              
              
               public static readonly ILoggerFactory MyLoggerFactory
            = LoggerFactory.Create(builder =>
            {
                builder
                    .AddFilter((category, level) =>
                        (category == DbLoggerCategory.ChangeTracking.Name |
                         category == DbLoggerCategory.Database.Transaction.Name |
                         category == DbLoggerCategory.Database.Command.Name)
                         && level == LogLevel.Debug)
                    .AddDebug();
            });

这将产生带有Entityframework Core发出的Change Tracking，Transaction和Command以及数据传递的调试日志，尤其要注意changetracking，因为它将识别您的对象是要添加还是更新

编辑1 调试：'DataContext'为new的'Id'属性生成了临时值'-9223372036854774805'

我看到Id没有价值，在您的控制器和savechanges之间有一些被删除的地方，您使用的是任何类型的映射，还是检查您的存储库，使用f11进行调试并查看丢失的地方

Answer 2

问题是，Id字段的可见性设置为false，这导致默认值分别为0。不绑定ID字段。我添加了一个@Html.HiddenFor(m => Model.Id)字段，现在它可以正常工作了。

EF核心插入新记录而不是更新

2 个答案: