ASPxTreeList.HtmlRowPrepared Event

Enables the settings of individual rows to be changed.

Namespace: DevExpress.Web.ASPxTreeList

Assembly: DevExpress.Web.ASPxTreeList.v23.2.dll

NuGet Package: DevExpress.Web

Declaration

C#

public event TreeListHtmlRowEventHandler HtmlRowPrepared

VB.NET

Public Event HtmlRowPrepared As TreeListHtmlRowEventHandler

Event Data

The HtmlRowPrepared event's data class is TreeListHtmlRowEventArgs. The following properties provide information specific to this event:

Property	Description
Level	Gets the nesting level of the processed node.
NodeKey	Gets the processed node’s key value.
Row	Gets the processed row.
RowKind	Gets the processed row’s type.

The event data class exposes the following methods:

Method	Description
GetValue(String)	Returns the value of the specified cell within the processed row.

Remarks

The HtmlRowPrepared event is raised for each row (node, preview, footer, group footer) within the ASPxTreeList. Handle this event to change the style settings of individual rows. The TreeListHtmlRowEventArgs.RowKind property identifies the processed row’s type.

Note

During export operations, the Tree View control ignores appearance settings specified in the HtmlRowPrepared event handler. Refer to the following topic for more information on how to customize exported elements: Export Tree List Data.

Limitations

The NullReferenceException is raised if you pass a hidden column’s field name to the event argument’s e.GetValue method. Use the following technique to get a hidden column’s value:

1. Pass the e.NodeKey event argument’s value to the Tree List’s ASPxTreeList.FindNodeByKeyValue method to obtain the Tree List node for the processed HTML row.

2. Call the node’s TreeListNode.GetValue(String) method with the hidden column’s field name as an argument to get the cell value.

The code sample bellow illustrates this technique:

protected void treeList_HtmlDataCellPrepared(object sender, TreeListHtmlDataCellEventArgs e) {
    int cellValue;
    if (treeList.DataColumns["ColumnName"].Visible) {
        cellValue = (int)e.GetValue("ColumnName"); 
    }
    else {
        cellValue = (int)treeList.FindNodeByKeyValue(e.NodeKey).GetValue("ColumnName");
    }
    // ...
}

Example

This example shows how to paint individual data cells and entire nodes depending upon the ASPxTreList’s data. The ASPxTreeList.HtmlDataCellPrepared event is handled to custom paint budgets that are greater than $1,000,000.

The ASPxTreeList.HtmlRowPrepared event is handled to custom paint departments located at Monterey.

The image below shows the result:

C#

using System.Drawing;

protected void treeList_HtmlRowPrepared(object sender, TreeListHtmlRowEventArgs e) {
    if(Object.Equals(e.GetValue("Location"), "Monterey"))
        e.Row.BackColor = Color.FromArgb(211, 235, 183);
}

protected void treeList_HtmlDataCellPrepared(object sender, TreeListHtmlDataCellEventArgs e) {
    if(e.Column.Name == "budget") {
        decimal value = (decimal)e.CellValue;
        e.Cell.BackColor = GetBudgetColor(value);
        if(value > 1000000M)
            e.Cell.Font.Bold = true;
    }
}

VB.NET

Imports System.Drawing

Protected Sub treeList_HtmlRowPrepared(ByVal sender As Object, ByVal e As TreeListHtmlRowEventArgs)
   If Object.Equals(e.GetValue("Location"), "Monterey") Then
      e.Row.BackColor = Color.FromArgb(211, 235, 183)
   End If
End Sub

Protected Sub treeList_HtmlDataCellPrepared(ByVal sender As Object,_
ByVal e As TreeListHtmlDataCellEventArgs)
   If e.Column.Name = "budget" Then
      Dim value As Decimal = CDec(e.CellValue)
      e.Cell.BackColor = GetBudgetColor(value)
      If value > 1000000D Then
         e.Cell.Font.Bold = True
      End If
   End If
End Sub