实体框架更新一条记录会删除另一条记录

Question

I'm altering a business application to introduce a new entity SalesOrderReason. This will tie into another entity SalesOrder based on a SalesOrderReasonID field.

What I would like this code to do is to set the SalesOrderReasonID of the sales order (called from a button press - this is a desktop application).

In reality, what is happening is the first time it runs, it sets the SalesOrderReasonID - that's great. When I set the SalesOrderReasonID for the next SalesOrder it sets it correctly however it deletes a previous SalesOrder from the database which is obviously unwanted behavior.

I've had a similar issue previously where the relationship was configured incorrectly (I had put WithOne instead of WithMany) which gave the same symptoms, because of this I believe it's related to the configuration.

I've tried to configure it from the other perspective as well (SalesOrderReason config) without any success. (Here is that attempt, I created an ICollection SalesOrdersWithReason on SalesOrderReason for this)

builder.HasMany(e => e.SalesOrdersWithReason)
    .WithOne(s => s.SalesOrderReason)
    .HasForeignKey(s => s.SalesOrderReasonID);

(Sorry if this is too much code I've tried to strip away what I thought was not relevant.)

This is the SalesOrder entity.

public class SalesOrder
{
    public int ID { get; set; }
    public int SalesOrderReasonID { get; set; }
    public SalesOrderReason SalesOrderReason { get; set; }
}

This is the SalesOrderReason entity

public class SalesOrderReason
{
    public int Id { get; set; }
    public string Reason { get; set; }
    public DateTime DateCreated { get; set; }
}

This is my configuration using fluent API

public class SalesOrderConfiguration : IEntityTypeConfiguration<SalesOrder>
{
    public void Configure(EntityTypeBuilder<SalesOrder> builder)
    {
        
        builder.HasKey(e => e.ID);

        builder.Property(e => e.ID)
            .ValueGeneratedOnAdd();

        builder.HasOne(s => s.SalesOrderReason)
            .WithMany()
            .HasForeignKey(s => s.SalesOrderReasonID);
    }
}

This is the Save method in my Repository

public void Save() => _context.SaveChanges();

It all goes wrong here when saving a change to the SalesOrderReasonID

private static void ChangeSalesOrderReason(SalesOrder salesOrder, int salesOrderReasonID)
{
    salesOrder.SalesOrderReasonID = salesOrderReasonID;
    SalesOrderRepository.Save();
}

Edit to include UI code as requested The SalesOrder in this use case is an existing object which comes from a Telerik gridview row, it gets selected then the user presses a button to update the SalesOrderReason on the SalesOrder to the one in a DropDownList.

The UI is in VB.Net (Odd I know but it's part of a legacy project we're rebuilding) the above C# code is in separate C# projects added as reference in the VB project.

Private Sub UpdateReasonButton_Click(sender As Object, e As EventArgs) Handles UpdateReasonButton.Click
    For Each salesOrderRow As GridViewRowInfo In SalesOrderGridView.SelectedRows
        SalesOrderController.ChangeSalesOrderReason(salesOrderRow.DataBoundItem, ReasonList.SelectedValue)
    Next
End Sub

Answer 1

按照 Panagiotis Kanavos 的评论，我调整了我的 DbContext 以使其寿命更短，我没有时间创建适当的“工作单元”模式，而只是在我的代码命中存储库时重新创建上下文似乎可以解决问题。