TreeListCustomizeElementEventArgs.CssClass Property

Assign a CSS class to a TreeList element.

Namespace: DevExpress.Blazor

Assembly: DevExpress.Blazor.v24.1.dll

NuGet Package: DevExpress.Blazor

Declaration

public string CssClass { get; set; }

Property Value

Type	Description
String	CSS class names delimited by spaces.

Remarks

If you specify the CssClass property and class attribute in the Attributes collection at the same time, the TreeList uses the CssClass property value.

The following code customizes the appearance of TreeList elements that meet the following criteria:

• Rows that have child rows are highlighted.
• Cells in March Change and September Change columns that display values larger than 5% are colored green.
• Cells in March Change and September Change columns that display negative values are colored red.

Run Demo: Conditional Formatting

<DxTreeList Data="Data"
            KeyFieldName="ID"
            ParentKeyFieldName="RegionID"
            CustomizeElement="TreeList_CustomizeElement">
    <Columns>
        <DxTreeListDataColumn FieldName="Region" />
        <DxTreeListDataColumn FieldName="MarchSales" DisplayFormat="c0" />
        <DxTreeListDataColumn FieldName="SeptemberSales" DisplayFormat="c0" />
        <DxTreeListDataColumn FieldName="MarchChange" DisplayFormat="p2" />
        <DxTreeListDataColumn FieldName="SeptemberChange" DisplayFormat="p2" />
        <DxTreeListDataColumn FieldName="MarketShare" DisplayFormat="p0" />
    </Columns>
</DxTreeList>

@code {
    object Data { get; set; }

    protected override void OnInitialized () {
        Data = SalesByRegionDataProvider.GenerateData();
    }

    void TreeList_CustomizeElement(TreeListCustomizeElementEventArgs e) {
        if(e.ElementType == TreeListElementType.DataRow 
                         && (int)e.TreeList.GetRowValue(e.VisibleIndex, "RegionID") == 0) {
            e.CssClass = "parent-region-row";
        }
        if(e.ElementType == TreeListElementType.DataCell && e.Column is ITreeListDataColumn dataColumn) {
            if(dataColumn.FieldName == "MarchChange" || dataColumn.FieldName == "SeptemberChange") {
                var value = (decimal)e.TreeList.GetRowValue(e.VisibleIndex, dataColumn.FieldName);
                if(value > 0.05M) {
                    e.CssClass = "win-threshold";
                }
                else if(value < 0) {
                    e.CssClass = "loss-threshold";
                }
            }
        }
    }
}

.parent-region-row {
    background-color: color-mix(in srgb, var(--bs-gray-300), transparent 50%);
}
td.loss-threshold {
    background-color: rgba(245, 198, 203, 0.5);
}
td.win-threshold {
    background-color: rgba(198, 245, 203, 0.5);
}

For more information on how to apply CSS classes to DevExpress Blazor components, refer to the following help topic: CSS Classes.

If your custom CSS ruleset includes only one class selector, some property declarations can be ignored. DevExpress themes can apply predefined CSS rules that are more specific and have higher priority than a single-selector rule. Make your rule more specific to increase the priority of your ruleset. See the following help topic for an example: Apply Styles to Components. For more information about how a browser calculates rule priority, refer to the following topic: Understanding the cascade.

You can use the !important flag to override other CSS rules. However, note that this flag modifies the standard behavior of the cascade, which can make troubleshooting CSS issues quite challenging, particularly in large stylesheets.

For more information and examples, refer to the CustomizeElement event’s description.