Question

Does Entity Framework incorrectly detect changes to images?

I have a “Person” entity class defined as follows;

public class Person
{
 public int Id { get; set; }
 public byte[] Photo { get; set; }
}

I have bound the Photo to a PictureBox control on my form using a datasource.
There form also uses a dynamically created bindingNavigator.

I also have written an audit log to populate captured changes
The procedure calls the ObjectContext DetectChanges() and then

var entries = ObjectContext.ObjectStateManager.GetObjectStateEntries()    

Which contains an entry showing that the Photo has been modified.
entry.OriginalValues[name] matches entry.CurrentValues[name]

The Column is varbinary(MAX) in SQL Server and the size of the picture files I have loaded are under 1Mb

If I set all of the columns to null the error no longer occurs

The code I use to get the file is

private void LoadPhotoButton_Click(object sender, EventArgs e)
{
   using (var dlg = new OpenFileDialog())
  {
      dlg.Filter = "JPEG files |*.jpg";
      if (dlg.ShowDialog() == DialogResult.OK)
      {
          PhotoPictureBox.Image = Image.FromFile(dlg.FileName);
      }
   }
 }

I note here that hex zero can be inserted as padding characters when these fields are involved in string conversion…. could the binding be doing that somehow?

If I delete the picturebox from the form, or even bind the control as a text box instead of a picturebox then the behaviour is correct ( not that a picture bound to a text box is any use )

I am able to work around the problem by not binding directly to the picture box.
Instead I just load it on the BindingSource_CurrentChanged event using

private void BindingSource_CurrentChanged(object sender, EventArgs e)
    {
        var obj = (Person) BindingSource.Current;
        this.PictureBox.Image = byteArrayToImage( obj.Photo);
    }

public Image byteArrayToImage(byte[] byteArrayIn)
    {
        MemoryStream ms = new MemoryStream(byteArrayIn);
        Image returnImage = Image.FromStream(ms);
        return returnImage;
    }

Answer 1

I am using my work around – documented at the end of the question as a make do answer.