Entity Framework: “Store update, insert, or delete

Question

I am using Entity Framework to populate a grid control. Sometimes when I make updates I get the following error:

Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries.

I can't figure out how to reproduce this. But it might have something to do with how close together I make the updates. Has anyone seen this or does anyone know what the error message refers to?

Edit: Unfortunately I am no longer at liberty to reproduce the problem I was having here, because I stepped away from this project and don't remember if I eventually found a solution, if another developer fixed it, or if I worked around it. Therefore I cannot accept any answers.

Answer 1

I also came across this error. The problem it turned out was caused by a Trigger on the table I was trying to save to. The Trigger used 'INSTEAD OF INSERT' which means 0 rows ever got inserted to that table, hence the error. Luckily in may case the trigger functionality was incorrect, but I guess it could be a valid operation that should somehow be handled in code. Hope this helps somebody one day.

Answer 2

The line [DatabaseGenerated(System.ComponentModel.DataAnnotations.DatabaseGeneratedOption.None)] did the trick in my case:

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;


[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int? SomeNumber { get; set; }

Answer 3

I ran into this using Telerik's RadGrid. I had the primary key as a gridbound column that was set to read only. It would work fine if the column was display="false" but readonly="true" caused the problem. I solved it by having the gridbound column display=false and adding a separate template column for display

<telerik:GridBoundColumn HeaderText="Shouldnt see" Display="false" 
     UniqueName="Id" DataField="Id">
</telerik:GridBoundColumn>
<telerik:GridTemplateColumn HeaderText="Id" UniqueName="IdDisplay">
    <ItemTemplate>
        <asp:Label ID="IDLabel" runat="server" 
            Text='<%# Eval("Id") %>'></asp:Label>                               
    </ItemTemplate>
</telerik:GridTemplateColumn> 

Answer 4

I came across this issue on a table that was missing a primary key and had a DATETIME(2, 3) column (so the entity's "primary key" was a combination of all the columns)... When performing the insert the timestamp had a more precise time (2018-03-20 08:29:51.8319154) that was truncated to (2018-03-20 08:29:51.832) so the lookup on key fields fails.

Answer 5

This will also happen if you are trying to insert into a unique constraint situation, ie if you can only have one type of address per employer and you try to insert a second of that same type with the same employer, you will get the same problem.

OR

This could also happen if all of the object properties that were assigned to, they were assigned with the same values as they had before.

        using(var db = new MyContext())
        {
            var address = db.Addresses.FirstOrDefault(x => x.Id == Id);

            address.StreetAddress = StreetAddress; // if you are assigning   
            address.City = City;                   // all of the same values
            address.State = State;                 // as they are
            address.ZipCode = ZipCode;             // in the database    

            db.SaveChanges();           // Then this will throw that exception
        }

Answer 6

That's a side-effect of a feature called optimistic concurrency.

Not 100% sure how to turn it on/off in Entity Framework but basically what it's telling you is that between when you grabbed the data out of the database and when you saved your changes someone else has changed the data (Which meant when you went to save it 0 rows actually got updated). In SQL terms, their update query's where clause contains the original value of every field in the row, and if 0 rows are affected it knows something's gone wrong.

The idea behind it is that you won't end up overwriting a change that your application didn't know has happened - it's basically a little safety measure thrown in by .NET on all your updates.

If it's consistent, odds are it's happening within your own logic (EG: You're actually updating the data yourself in another method in-between the select and the update), but it could be simply a race condition between two applications.