How can I paste selected cells on datagrid bounded by entity framework?

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C#

WPF

DataGrid

After frequent search on almost all sites, I've failed to get a solution to the problem. My datagrid is bound to SQL server database using entity framework hence no MVVM pattern. The copy from datagrid seems to work with a few codes (seems inbuilt) but the paste has failed. The available solutions generate errors, ie datagrid doesn't contain a definition for selectedCell...

HOW BEST CAN I PASTE DATA FROM EXCEL TO WPF DATAGRID ENTITY FRAMEWORK BASED...

What I have tried:

private void OnKeyDown(object sender, KeyEventArgs e)
{
    if (e.Key == Key.C && (Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control)
    {
        // DataObject d = ClipboardHelper.ParseClipboardData(); Clipboard.SetDataObject(d);
    }

    if (e.Key == Key.V &&
        (Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control)
    {

        // 2-dim array containing clipboard data
        string[][] clipboardData =
            ((string)Clipboard.GetData(DataFormats.Text)).Split('\n')
            .Select(row =>
                row.Split('\t')
                .Select(cell =>
                    cell.Length > 0 && cell[cell.Length - 1] == '\r' ?
                    cell.Substring(0, cell.Length - 1) : cell).ToArray())
            .Where(a => a.Any(b => b.Length > 0)).ToArray();

        // the index of the first DataGridRow
        int startRow = ItemContainerGenerator.IndexFromContainer(
           (DataGridRow)ItemContainerGenerator.ContainerFromItem(SelectedCells[0].Item));
        int targetRowCount = SelectedCells.Count;

        // the destination rows
        //  (from startRow to either end or length of clipboard rows)
        DataGridRow[] rows =
            Enumerable.Range(
                startRow, Math.Min(Items.Count, targetRowCount))
            .Select(rowIndex =>
                ItemContainerGenerator.ContainerFromIndex(rowIndex) as DataGridRow)
            .Where(a => a != null).ToArray();

        // the destination columns
        //  (from selected row to either end or max. length of clipboard colums)
        DataGridColumn[] columns = Columns.OrderBy(column => column.DisplayIndex)
            .SkipWhile(column => column != this.CurrentCell.Column)
            .Take(clipboardData.Max(row => row.Length)).ToArray();

        for (int rowIndex = 0; rowIndex < rows.Length; rowIndex++)
        {
            string[] rowContent = clipboardData[rowIndex % clipboardData.Length];
            for (int colIndex = 0; colIndex < columns.Length; colIndex++)
            {
                string cellContent =
                    colIndex >= rowContent.Length ? "" : rowContent[colIndex];
                columns[colIndex].OnPastingCellClipboardContent(
                    rows[rowIndex].Item, cellContent);
            }
        }

    }
}