DataGridViewComboBoxCell Binding - "value is not valid"

I'm trying to bind separate ComboBox cells within a DataGridView to a custom class, and keep getting an error

DataGridViewComboBoxCell value is not valid

I'm currently assigning the data source for the cell to an IList<ICustomInterface> from a Dictionary I've got. Upon setting the data source however, the index for the ComboBoxCell isn't set, so it has an invalid value selected.

I'm trying to figure out how to get it to select a real value, e.g. the 0th item within the list it has been given to remove this error, or find another way to solve the problem. Anyone have any suggestions?

Solution 1:

I managed to find the solution not long after posting the question. For anyone else:

The problem was that I was trying to assign the DataGridViewComboBoxCell.Value to an object, expecting that because the Cell was bound to a data source that it would automatically find the object in the source and update.

This wasn't actually the case, you actually need to set the value equal to that of the ValueMember property for it to correctly update the value and binding. I believe I was using a property 'Name' for both ValueMember and DisplayMember (controls how the renders in the cell) so setting the Value to interface.ToString() (rather than the interface instance) works for the majority of cases. Then I catch and ignore any DataError exceptions that occur while I'm changing the source around.

Solution 2:

Here's my simple solution when using enums

ColumnType.ValueType = typeof (MyEnum);
ColumnType.DataSource = Enum.GetValues(typeof (MyEnum));

you can do that just after "InitializeComponent();"

Solution 3:

Afters hours of trials, I finally found a solution that works.

// Create a DataGridView
System.Windows.Forms.DataGridView dgvCombo = new System.Windows.Forms.DataGridView();

// Create a DataGridViewComboBoxColumn
System.Windows.Forms.DataGridViewComboBoxColumn colCombo = new 

System.Windows.Forms.DataGridViewComboBoxColumn();

// Add the DataGridViewComboBoxColumn to the DataGridView
dgvCombo.Columns.Add(colCombo);

// Define a data source somewhere, for instance:
public enum DataEnum
{
    One,
    Two,
    Three
}

// Bind the DataGridViewComboBoxColumn to the data source, for instance:
colCombo.DataSource = Enum.GetNames(typeof(DataEnum));

// Create a DataGridViewRow:
DataGridViewRow row = new DataGridViewRow();

// Create a DataGridViewComboBoxCell:
DataGridViewComboBoxCell cellCombo = new DataGridViewComboBoxCell();

// Bind the DataGridViewComboBoxCell to the same data source as the DataGridViewComboBoxColumn:
cellCombo.DataSource = Enum.GetNames(typeof(DataEnum));

// Set the Value of the DataGridViewComboBoxCell to one of the values in the data source, for instance:
cellCombo.Value = "Two";
// (No need to set values for DisplayMember or ValueMember.)

// Add the DataGridViewComboBoxCell to the DataGridViewRow:
row.Cells.Add(cellCombo);

// Add the DataGridViewRow to the DataGridView:
dgvCombo.Rows.Add(row);

// To avoid all the annoying error messages, handle the DataError event of the DataGridView:
dgvCombo.DataError += new DataGridViewDataErrorEventHandler(dgvCombo_DataError);

void dgvCombo_DataError(object sender, DataGridViewDataErrorEventArgs e)
{
    // (No need to write anything in here)
}

That is all.

Solution 4:

I had the same problem.

In my case the solution was to fill the data adapter of the Foreign key table. This was not being automatically filled and this was the cause of the problem.

In the Page_Load Event:

Me.TblUserTypesTableAdapter.Fill(Me.DonateDataSet.tblUserTypes)

Solution 5:

I am having the same problem. After populating my ComboBox column in the (unbouod) DataGrid, I solved my problem by setting the ValueMember property of the DataGridViewComboBoxColumn Apparently, just relying on the ToString() property of the objects in the ComboBox is not enough.

Actual code:

/// <summary>
/// Populate the dataGridSplitVolumes data grid with all existing qualifications for the plan.
/// </summary>
/// <param name="bonus"></param>
private void PopulateDataGridSplitVolumes(Bonus_Group bonus)
{
  try
  {
    List<Qualification> qualifications = Qualification.Load(this.groupBonus.PlanID, this.ConnectionString);
    foreach (Qualification qual in qualifications)
    {
      DataGridViewComboBoxColumn col = (DataGridViewComboBoxColumn)this.dataGridSplitVolumes.Columns[0];
      col.Items.Add(qual);                    
    }
    SplitVolumeGrid_QualificationColumn.ValueMember = "Name";
  }
  catch (Exception ex)
  {
#if DEBUG
    System.Diagnostics.Debugger.Break();
#endif
    throw ex;
  }
}//PopulateDataGridSplitVolumes