在SET子句中多次指定列名

Question

我正在使用EntityFrameworkCore（AspNetCore），我试图从ajax调用更新模型（Pack）。在我的更新中，我想插入负面的实体 （或0）id并更新具有正常id的实体。我不知道它是好还是坏，所以如果你有一些提示。

以下是一些模型：

public class Pack
{
    [Key]
    public int PackId { get; set; }  
    public string PackName { get; set; }
    public ICollection<CardPack> CardPacks { get; set; }
}

public class CardPack
{
    [Key]
    [ForeignKey("Card")]
    public int CardId { get; set; }    
    [Key]
    [ForeignKey("Pack")]
    public int PackId { get; set; }    
    public Card Card { get; set; }
    public Pack Pack { get; set; }
}

public class Card
{
    [Key]
    public int CardId { get; set; }
    public ICollection<FaceCard> FaceCards { get; set; }
}

复合pk的我的Db上下文：

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);
    foreach (var relationship in 
        modelBuilder.Model.GetEntityTypes().SelectMany(e => 
        e.GetForeignKeys()))
    {
        relationship.DeleteBehavior = DeleteBehavior.Restrict;
    }

    modelBuilder.Entity<CardPack>(entity =>
    {
        entity.HasKey(t => new { t.CardId, t.PackId });
    });
}

这是更新方法。

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> SavePackWithAllCards([FromBody] Pack pack)
{         
// I don't use this pack for the example, i create a new one


    var newPack = new Pack
    {                
        PackName = "test"
    };

    _context.Add(newPack);

    await _context.SaveChangesAsync();        

    var cardpacks = new List<CardPack>();
    var cardpack = new CardPack
    {
        CardId = 0, // random negative number
        PackId = 0,
        Card = new Card
        {
            CardId = 0
        }
    };
    cardpacks.Add(cardpack);
    newPack.CardPacks = cardpacks;
    try
    {
        _context.Packs.Update(newPack);
        await _context.SaveChangesAsync();

        return RedirectToAction("Index");
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.StackTrace);
        return RedirectToAction("error", "home");
    }

}

我在对象包中的例子

我遇到以下错误。

   {Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while updating the entries. See the inner exception for details. ---> System.Data.SqlClient.SqlException: The column name 'PCK_ID' is specified more than once in the SET clause or column list of an INSERT. A column cannot be assigned more than one value in the same clause. Modify the clause to make sure that a column is updated only once. If this statement updates or inserts columns into a view, column aliasing can conceal the duplication in your code.
       at System.Data.SqlClient.SqlCommand.<>c.<ExecuteDbDataReaderAsync>b__107_0(Task`1 result)
       at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
       at System.Threading.Tasks.Task.Execute()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.<ExecuteAsync>d__26.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.<ExecuteAsync>d__32.MoveNext()
       --- End of inner exception stack trace ---
       at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.<ExecuteAsync>d__32.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.<ExecuteAsync>d__10.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.EntityFrameworkCore.Storage.Internal.SqlServerExecutionStrategy.<ExecuteAsync>d__6`2.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.<SaveChangesAsync>d__54.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.<SaveChangesAsync>d__52.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.EntityFrameworkCore.DbContext.<SaveChangesAsync>d__35.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
       at FicheTips.Web.Controllers.PackController.<SavePackWithAllCards>d__13.MoveNext() in C:\VS2017\Projects\FicheTips\FicheTips\FicheTips.Web\Controllers\PackController.cs:line 355}