DataGridViewComboBoxCell.DataSource Property


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Gets or sets the data source whose data contains the possible selections shown in the drop-down list.

Namespace:   System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

Public Overridable Property DataSource As Object

Property Value

Type: System.Object

An IList or IListSource that contains a collection of values used to supply data to the drop-down list. The default value is null.

Exception Condition

The specified value when setting this property is not null and is not of type IList nor IListSource.

Typically this property will be set for an entire column of cells through the DataGridViewComboBoxColumn.DataSource property.

If possible, set DataSource to a source containing only the possible selections, like a column of selections. Then the DisplayMember property doesn't need to be set. But if the source is more complicated, set DisplayMember to the name of the property or column from which to retrieve possible selections.

If DataSource is set to a string array, then ValueMember and DisplayMember do not need to be set because each string in the array will be used for both value and display.

Changing the DataSource property causes the cell to reinitialize its Items collection and redraw itself.

When you change the value of the DataSource property, the control attempts to use the ValueMember and DisplayMember property values with the new data source, and sets each property to null if its value cannot be found. Any exception that occurs during this process is ignored unless it is one of the following critical exceptions: NullReferenceException, StackOverflowException, OutOfMemoryException, ThreadAbortException, ExecutionEngineException, IndexOutOfRangeException, or AccessViolationException.

When the DataSource is set, the DataGridViewComboBoxCell attaches to the Disposed event of the data source. When the DataGridViewComboBoxCell is detached from the DataGridView, the resource is not immediately released. The DataGridViewComboBoxCell resource is released when the attached data source is disposed. To release the resource for garbage collection immediately, set the DataSource property to null.

The following code example demonstrates the use of the DataGridViewComboBoxColumn.DataSource property, which is similar to this property. This example is part of a larger example available in the DataGridViewComboBoxColumn class overview topic.

Private Function CreateComboBoxColumn() _
    As DataGridViewComboBoxColumn
    Dim column As New DataGridViewComboBoxColumn()

    With column
        .DataPropertyName = ColumnName.TitleOfCourtesy.ToString()
        .HeaderText = ColumnName.TitleOfCourtesy.ToString()
        .DropDownWidth = 160
        .Width = 90
        .MaxDropDownItems = 3
        .FlatStyle = FlatStyle.Flat
    End With
    Return column
End Function

Private Sub SetAlternateChoicesUsingDataSource( _
    ByVal comboboxColumn As DataGridViewComboBoxColumn)
    With comboboxColumn
        .DataSource = RetrieveAlternativeTitles()
        .ValueMember = ColumnName.TitleOfCourtesy.ToString()
        .DisplayMember = .ValueMember
    End With
End Sub

Private Function RetrieveAlternativeTitles() As DataTable
    Return Populate( _
        "SELECT distinct TitleOfCourtesy FROM Employees")
End Function

Private connectionString As String = _
        "Integrated Security=SSPI;Persist Security Info=False;" _
        & "Initial Catalog=Northwind;Data Source=localhost"

Private Function Populate(ByVal sqlCommand As String) As DataTable
    Dim northwindConnection As New SqlConnection(connectionString)

    Dim command As New SqlCommand(sqlCommand, _
    Dim adapter As New SqlDataAdapter()
    adapter.SelectCommand = command
    Dim table As New DataTable()
    table.Locale = System.Globalization.CultureInfo.InvariantCulture

    Return table
End Function

' Using an enum provides some abstraction between column index
' and column name along with compile time checking, and gives
' a handy place to store the column names.
Enum ColumnName
End Enum

.NET Framework
Available since 2.0
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