What are Effective Ways to Persist State in WinForms GridDataBoundGrid?
There is no built in support for this, but you could track the expand states and save them to disk and reload them. Here is a little sample that does this using an XML file to save the primary keys for the expanded rows. (It assumes only a parent-child grid. For multi-levels, it would be more complicated.) in WinForms GridDataBoundGrid.
C#
ArrayList expandState = new ArrayList();
private void gridDataBoundGrid1_RowExpanded(object sender, GridRowEventArgs e)
{
//assumes a primary key value in "parentID" column
int col = this.gridDataBoundGrid1.Binder.NameToColIndex(keyColumn);
int key = (int) this.gridDataBoundGrid1[e.RowIndex, col].CellValue;
expandState.Add(key);
}
private void gridDataBoundGrid1_RowCollapsed(object sender, GridRowEventArgs e)
{
//assumes a primary key value in keyColumn column
int key = (int) this.gridDataBoundGrid1[e.RowIndex, this.gridDataBoundGrid1.Binder.NameToColIndex
(keyColumn)].CellValue;
expandState.Remove(key);
}
private void Form1_Closing(object sender, CancelEventArgs e)
{
SaveState();
}
private void LoadState()
{
string fileName = "persistedExpandStates.xml";
if(File.Exists(fileName))
{
expandState.Clear();
Stream s = File.OpenRead(fileName);
try
{
XmlSerializer serializer = new XmlSerializer(typeof(int[]));
expandState = new ArrayList((int[])serializer.Deserialize(s));
}
catch
{
expandState.Clear();
}
finally
{
s.Close();
}
}
expandState.Sort(); //order the keys so can be expanded from bottom up so pos matched grid row
for(int i = expandState.Count - 1; i >= 0; i--)
{
int pos = FindKeyValue(expandState[i]);
if(pos > -1)
{
this.gridDataBoundGrid1.ExpandAtRowIndex(pos + this.gridDataBoundGrid1.Model.Rows.HeaderCount + 1);
}
}
}
private void SaveState()
{
string fileName = "persistedExpandStates.xml";
int[] expandStates = (int[])expandState.ToArray(typeof(int));
XmlSerializer serializer = new XmlSerializer(typeof(int[]));
TextWriter writer = new StreamWriter(fileName);
serializer.Serialize(writer, expandStates);
writer.Close();
}
private int FindKeyValue(object key)
{
int col = this.gridDataBoundGrid1.Binder.NameToColIndex(keyColumn);
int row = -1;
for(int i = 0; i < this.parentTable.DefaultView.Count; ++i)
{
if(this.parentTable.DefaultView[i][keyColumn].Equals(key))
{
row = i;
break;
}
}
return row;
}
VB
Dim expandState As New ArrayList()
Private Sub gridDataBoundGrid1_RowExpanded(sender As Object, e As GridRowEventArgs)
''assumes a primary key value in "parentID" column
Dim col As Integer = Me.gridDataBoundGrid1.Binder.NameToColIndex(keyColumn)
Dim key As Integer = CInt(Me.gridDataBoundGrid1(e.RowIndex, col).CellValue)
expandState.Add(key)
End Sub ''gridDataBoundGrid1_RowExpanded
Private Sub gridDataBoundGrid1_RowCollapsed(sender As Object, e As GridRowEventArgs)
''assumes a primary key value in keyColumn column
Dim key As Integer = CInt(Me.gridDataBoundGrid1(e.RowIndex,
Me.gridDataBoundGrid1.Binder.NameToColIndex(keyColumn)).CellValue)
expandState.Remove(key)
End Sub ''gridDataBoundGrid1_RowCollapsed
Private Sub Form1_Closing(sender As Object, e As CancelEventArgs)
SaveState()
End Sub ''Form1_Closing
Private Sub LoadState()
Dim fileName As String = "persistedExpandStates.xml"
If File.Exists(fileName) Then
expandState.Clear()
Dim s As Stream = File.OpenRead(fileName)
Try
Dim serializer As New XmlSerializer(GetType(Integer()))
expandState = New ArrayList(CType(serializer.Deserialize(s), Integer()))
Catch
Finally
s.Close()
End Try
End If
expandState.Sort() ''order the keys so can be expanded from bottom up so pos matched grid row
Dim i As Integer
For i = expandState.Count - 1 To 0 Step -1
Dim pos As Integer = FindKeyValue(expandState(i))
If pos > - 1 Then
Me.gridDataBoundGrid1.ExpandAtRowIndex((pos + Me.gridDataBoundGrid1.Model.Rows.HeaderCount + 1))
End If
Next i
End Sub ''LoadState
Private Sub SaveState()
Dim fileName As String = "persistedExpandStates.xml"
Dim expandStates As Integer() = CType(expandState.ToArray(GetType(Integer)), Integer())
Dim serializer As New XmlSerializer(GetType(Integer()))
Dim writer = New StreamWriter(fileName)
serializer.Serialize(writer, expandStates)
writer.Close()
End Sub ''SaveState
Private Function FindKeyValue(key As Object) As Integer
Dim col As Integer = Me.gridDataBoundGrid1.Binder.NameToColIndex(keyColumn)
Dim row As Integer = - 1
Dim i As Integer
While i < Me.parentTable.DefaultView.Count
If Me.parentTable.DefaultView(i)(keyColumn).Equals(key) Then
row = i
Exit While
End If
End While
Return row
End Function ''FindKeyValue
Here is a sample that illustrates this:
Conclusion
I hope you enjoyed learning about the effective ways to persist state in WinForms GridDataBoundGrid.
You can refer to our WinForms GridDataBoundGrid feature tour page to know about its other groundbreaking feature representations. You can also explore our WinForms GridDataBoundGrid documentation to understand how to create and manipulate data.
For current customers, you can check out our components from the License and Downloads page. If you are new to Syncfusion, you can try our 30-day free trial to check out our other controls.
If you have any queries or require clarifications, please let us know in the comments section below. You can also contact us through our support forums, Direct-Trac, or feedback portal. We are always happy to assist you!
