Custom DataTable with DataRows that are have Tags

Question

It's possible to bind object to DataGridViewRow of DataGridView via Tag property:

var row = (DataGridViewRow)dataGridView1.RowTemplate.Clone();
row.Tag= new SomeClass();

But how to make some binding not with (DataGridViewRow)dataGridView1.RowTemplate.Clone() , but by using DataTable ?

I've made custom MyDataRow with public object Tag { get; set; } public object Tag { get; set; } public object Tag { get; set; } :

[Serializable]
public class MyDataRow : DataRow
{
    public object Tag { get; set; } 

    public MyDataRow()
        : base(null)
    {
    }

    public MyDataRow(DataRowBuilder builder)
        : base(builder)
    {
    }
}

And MyDataTable for it:

[Serializable]
public class MyDataTable : DataTable
{
    public MyDataTable()
        : base()
    {
    } 

    public MyDataTable(string tableName)
       : base(tableName)
    {
    }

    public MyDataTable(string tableName, string tableNamespace)
        : base(tableName, tableNamespace)
    {
    } 

    /// <summary>
    /// Needs using System.Runtime.Serialization;
    /// </summary>
    public MyDataTable(SerializationInfo info, StreamingContext context)
        : base(info, context)
    {
    } 

    protected override Type GetRowType()
    {
        return typeof(MyDataRow);
    } 

    protected override DataRow NewRowFromBuilder(DataRowBuilder builder)
    {
        return new MyDataRow(builder);
    }
}

After that I am trying to fill data:

MyDataTable dt = new MyDataTable();
                        MyDataRow dr = dt.NewRow() as MyDataRow;
                        dr.Tag = new SomeObject(); 

                        var arr = columns2.ToArray();
                        for (int x = 0; x < arr.Length; x++)
                        {
                            dr[x] = arr[x];
                        } 

                        dt.Rows.Add(dr);
dataGridView1.DataSource = dt;

As result, there are no Tag values in DataGridView1 row

private void DataGridView1_RowEnter(object sender, DataGridViewCellEventArgs e)
        {
            var row = dataGridView1.Rows[e.RowIndex];
            var l = (List<string>)row.Tag; // <-- Here is Exception occures, because row.Tag comes Null

How can I pass Tag values of rows for DataGridView with DataSources?

Answer 1

The DataGridViewRow 's .Tag is null because you didn't set it to anything . The fact that your MyDataRow has a .Tag itself is irrelevant and unrelated - completely different .Tag . One option would be to set the .Tag of the actual DataGridViewRow .

What you might want to do is look at the .DataBoundItem of the row; this should be your MyDataRow instance, but: it is possible that this will actually be the DataRowView , in which case you'll want to look at the .Row of that instead.

Answer 2

You probably might want to use separate column for "tag" purposes:

 class EventsDataTable : DataTable
 {
   public DataColumn ColumnVariables { get; set; }
   public DataColumn ColumnSource { get; set; }

   public EventsDataTable()
   {
     ColumnSource = new DataColumn("Source", typeof(string),
       null, MappingType.Element);
        base.Columns.Add(ColumnSource);

      ColumnVariables = new DataColumn("Variables", typeof(EventData),
        null, MappingType.Hidden);
      base.Columns.Add(ColumnVariables);
    }
  }

Then you can add rows and set a "raw" pointer to your fake column:

public void AddNewEvent(EventData eventData)
{
  DataRow dataRow = _eventsTable.NewRow();
  dataRow[_eventsTable.ColumnSource.ColumnName] = eventData.Source;
  dataRow[_eventsTable.ColumnVariables.ColumnName] = eventData;
  _eventsTable.Rows.Add(dataRow);
}