Question

I have a routine which converts all the data in a DataGridView to a corresponding DataTable. I want to extend this method to incorporate the ability to convert just the selected range of the DataGridView. I can clearly do this using basic logic if (bIsSelection) /*Do stuff*/ else /*Do other stuff*/ but I would like to use generics here. The problem is that the full DataGridView range is a DataGridViewColumnCollection and the selected range will be a DataGridViewSelectedColumnCollection and C# does not seem to like any conversion between the two, or allow implicit typing in the case of generics.

The first part of my code was

public static DataTable BuildDataSetFromDgv(DataGridView _dataGridView, 
    string strTabName)
{
    DataTable dt = new DataTable();

    dt.TableName = strTabName;
    foreach (DataGridViewColumn col in _dataGridView.Columns)
        dt.Columns.Add(col.DataPropertyName, col.ValueType);

and I have attempted

public static DataTable BuildDataSetFromDgv<T>(DataGridView _dataGridView, 
    string strTabName, ICollection<T> _columnColl, ICollection<T> _rowColl)
{
    DataTable dt = new DataTable();

    dt.TableName = strTabName;
    //foreach (DataGridViewColumn col in _dataGridView.Columns)
    foreach (DataGridViewColumn col in _columnColl)
        dt.Columns.Add(col.DataPropertyName, col.ValueType);

which does not work due to the implicit conversion, and changing _columnColl to _columnColl as DataGridView[Selected]ColumnCollection defeats the objective.

How do I make this work with generics in this case?

Thanks for your time.

Answer 1

I am not sure why you need a generic one – both are collection of DataGridViewColumn. For example, why below shouldn’t work for you

public static DataTable BuildDataSetFromDgv(DataGridView _dataGridView, 
    string strTabName, IEnumerable columns)
{
    DataTable dt = new DataTable();
    dt.TableName = strTabName;

    var dvgColumns = columns.Cast<DataGridViewColumn>();
    foreach (var col in dvgColumns)
        dt.Columns.Add(col.DataPropertyName, col.ValueType);