Modify Type of Dataset Column

[catlook]

I'm working with a windows foem application. I have a dataset that was returned from a webservice. The third column ("Permanent") contains a bool. When i bind the data to a datagridview, that coulmn shows up as a series of checked checkboxes (since all the rows happened to have "true" for that value). What I want to do is modify the dataset, before binding it to the grid, to display the word "Permanent" if the bool is true and "Temporary" is the bool is false. I've gotten the code the point where I recognise whether it's true or false, but, because the column expects a bool, I can't put in the appropriate string. Any suggestions?

private void btnGetAccounts_Click(object sender, EventArgs e)
{
  BindingSource bs = new BindingSource();
  dsAccounts = new DataSet();
  dsAccounts = myAccount.List(nSessionID, out nError, out sErrorMsg);
  if (dsAccounts != null && dsAccounts.Tables.Count > 0)
  { 
    //modify datadisplay
    for (int i = 0; i < 10; i++)
    {
      if ((bool)dsAccounts.Tables[0].Rows[i][2] == true)
     {
       dsAccounts.Tables[0].Rows[i][2] = "Permanent";
     }
   }

  bs.DataSource = dsAccounts;
  bs.DataMember = dsAccounts.Tables[0].TableName; 
  dgvAccounts.DataSource = bs;
  }
}

The error I get is: "String was not recognised as valid Boolean. Couldn't store "Permanent" in Permanent column. Expected type is Boolean."

It has been suggested that I use the RowDataBound event, but, sa far as I know, that only applies to ASP. That event doesn't seem to be available for DataGridViews in windows forms applications.

 

[davearia]

Hi,

You cannot modify the column type once you have data in there.

Here is what I would do, it's in vb as I am at work.

 Dim dtResults As New DataTable

For Each dc As DataColumn In dtOriginalTable.Columns
    dtResults.Columns.Add(dc.ColumnName)
Next

For Each dc As DataColumn In dtResults.Columns
    If dc.ColumnName = "columnToChange" Then
        dc.DataType = System.Type.GetType("System.String")
    End If
Next

For Each drow As DataRow In dtOriginalTable.Rows
    dtResults.Rows.Add(drow.ItemArray)
    If Convert.ToBoolean(dtResults.Rows(dtResults.Rows.Count - 1).Item("columnToChange")) Then
        dtResults.Rows(dtResults.Rows.Count - 1).Item("columnToChange") = "Permanent"
    Else
        dtResults.Rows(dtResults.Rows.Count - 1).Item("columnToChange") = "Temporary"
    End If
Next

So you bind to the new datatable and it should fine.

 

[dliedke]

Thanks a lot!! Great code, this is the version in C# only changing the column type:

DataTable dtOriginalTable = dataSet.Tables[0];

DataTable dtResults = new DataTable();
foreach (DataColumn dc in dtOriginalTable.Columns)
{
dtResults.Columns.Add(dc.ColumnName);
}

foreach (DataColumn dc in dtResults.Columns)
{
if (dc.ColumnName == "Incident Priority")
{
dc.DataType = System.Type.GetType("System.String");
}
}

foreach (DataRow drow in dtOriginalTable.Rows)
{
dtResults.Rows.Add(drow.ItemArray);
}