Added new kb article grid-kb-style-filtered-columns

knowledge-base/grid-style-filtered-columns.md

@@ -0,0 +1,120 @@
+---
+title: Change Filtered Columns Color in Grid for Blazor
+description: Learn how to change the background color of filtered columns in the Telerik Grid for Blazor for better visibility using CSS.
+type: how-to
+page_title: How to Style Filtered Columns in Telerik Grid for Blazor
+slug: grid-kb-style-filtered-columns
+tags: grid, blazor, styling, filtering, css, oncellrender, onstatechanged
+res_type: kb
+ticketid: 1672604
+---
+
+## Environment
+
+<table>
+    <tbody>
+        <tr>
+            <td>Product</td>
+            <td>Grid for Blazor</td>
+        </tr>
+    </tbody>
+</table>
+
+## Description
+
+I want to style filtered columns in the Grid for Blazor using RGBA for better visibility. Specifically, when a filter is applied, I want the background color of column cells to change.
+
+This knowledge base article answers the following questions:
+
+* How to apply custom styles to filtered columns in a Blazor Grid?
+* How to enhance the visibility of filtered columns in Blazor Grid using CSS?
+
+## Solution
+
+To style filtered columns in a Telerik Grid for Blazor: 
+
+1. Use the [`OnCellRender`]({%slug grid-column-events%}#oncellrender) and [`OnStateChanged`]({%slug grid-state%}#onstatechanged) events.
+2. Apply a custom CSS class to the filtered columns when a filter is active. The CSS class will be rendered on each cell from these columns.
+
+>caption Grid with styled filtered column.
+
+`````CSHTML
+@using Telerik.DataSource
+
+<TelerikGrid Data="@GridData"
+             TItem="@Employee"
+             FilterMode="@GridFilterMode.FilterRow"
+             OnStateChanged="@OnGridStateChanged"
+             Pageable="true"
+             Sortable="true">
+    <GridColumns>
+        <GridColumn Field="@nameof(Employee.ID)"
+                    OnCellRender="@( (GridCellRenderEventArgs args) => OnGridCellRender(args, nameof(Employee.ID)) )"/>
+        <GridColumn Field="@nameof(Employee.Name)"
+                    OnCellRender="@( (GridCellRenderEventArgs args) => OnGridCellRender(args, nameof(Employee.Name)) )" />
+        <GridColumn Field="@nameof(Employee.Salary)" DisplayFormat="{0:C0}"
+                    OnCellRender="@( (GridCellRenderEventArgs args) => OnGridCellRender(args, nameof(Employee.Salary)) )" />
+    </GridColumns>
+</TelerikGrid>
+
+<style>
+    .highlighted-column {
+        background-color: rgba(0,0,0, 0.04);
+        color: var(--kendo-color-primary);
+    }
+</style>
+
+@code {
+    private List<Employee> GridData { get; set; } = new();
+    private List<string> FilteredColumns { get; set; } = new();
+
+    private void OnGridCellRender(GridCellRenderEventArgs args, string field)
+    {
+        if (FilteredColumns.Contains(field))
+        {
+            args.Class = "highlighted-column";
+        }
+    }
+
+    private void OnGridStateChanged(GridStateEventArgs<Employee> args)
+    {
+        if (args.PropertyName == "FilterDescriptors")
+        {
+            FilteredColumns = new();
+
+            foreach (CompositeFilterDescriptor cfd in args.GridState.FilterDescriptors)
+            {
+                FilterDescriptor fd = (FilterDescriptor)cfd.FilterDescriptors.First();
+
+                FilteredColumns.Add(fd.Member);
+            }
+        }
+    }
+
+    protected override void OnInitialized()
+    {
+        for (int i = 1; i <= 50; i++)
+        {
+            GridData.Add(new Employee()
+            {
+                ID = i,
+                Name = $"Employee Name {i}",
+                Salary = Random.Shared.Next(1000, 10000)
+            });
+        }
+    }
+
+    public class Employee
+    {
+        public int ID { get; set; }
+        public string Name { get; set; } = string.Empty;
+        public decimal Salary { get; set; }
+    }
+}
+`````
+## See Also
+
+* [Grid Columns](https://docs.telerik.com/blazor-ui/components/grid/columns/bound)
+* [OnCellRender Event](https://docs.telerik.com/blazor-ui/components/grid/columns/events)
+* [OnStateChanged Event](https://docs.telerik.com/blazor-ui/components/grid/state#onstatechanged)
+* [Override the Theme or Apply Custom CSS Styles]({%slug themes-override%})