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Is there an effective way to persist the state of expanded/collapsed row when we re-bind the datasource into the grid(GridDataBoundGrid with one level hierarchy)?

Platform: WinForms |
Control: GridDataBoundGrid(Classic) |
Published Date: April 30, 2011 |
Last Revised Date: July 10, 2014

 

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.)

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:

http://websamples.syncfusion.com/samples/KB/Grid.Windows/PersistingExpandState/main.htm

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