Question

I have code that generates records based on my DataGridView. These records are temporary because some of them already exist in the database.

        Crop_Variety v = new Crop_Variety();
        v.Type_ID = currentCropType.Type_ID;
        v.Variety_ID = r.Cells[0].Value.ToString();
        v.Description = r.Cells[1].Value.ToString();
        v.Crop = currentCrop;
        v.Crop_ID = currentCrop.Crop_ID;

Unfortunately in this little bit of code, because I say that v.Crop = currentCrop,
now currentCrop.Crop_Varieties includes this temporary record. And when I go to insert the records of this grid that are new, they have a reference to the same Crop record, and therefore these temporary records that do already exist in the database show up twice causing duplicate key errors when I submit.

I have a whole system for detecting what records need to be added and what need to be deleted based on what the user has done, but its getting gummed up by this relentless tracking of references.

Is there a way I can stop Linq-To-Sql from automatically adding these temporary records to its table collections?

Answer 1

I would suggest revisiting the code that populates DataGridView (grid) with records.

And then revisit the code that operates on items from a GridView, keeping in mind that you can grab bound item from a grid row using the following code:

public object GridSelectedItem
{
    get
    {
        try
        {
            if (_grid == null || _grid.SelectedCells.Count < 1) return null;
            DataGridViewCell cell = _grid.SelectedCells[0];
            DataGridViewRow row = _grid.Rows[cell.RowIndex];
            if (row.DataBoundItem == null) return null;
            return row.DataBoundItem;
        }
        catch { }
        return null; 
    }
}

It is also hard to understand the nature of Crop_Variety code that you have posted. As the Crop_Variety seems to be a subclass of Crop. This leads to problems when the Crop is not yet bound to database and potentially lead to problems when you’re adding Crop_Variety to the context.

For this type of Form application I normally have List _dataList inside form class, then the main grid is bound to that list, through ObjectBindingList or another way. That way _dataList holds all data that needs to be persisted when needed (user clicked save).