Added new kb article grid-highlight-filter-icon

Author: KB Bot

knowledge-base/grid-highlight-filter-icon.md

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+---
+title: Filter Icon Not Highlighted 
+description: This article demonstrates how to fix the filter menu icon not being highlighted when filters are applied programmatically.
+type: troubleshooting
+page_title: How to Highlight Filter Icon in a Blazor Grid with Pre-applied Filters
+slug: grid-highlight-filter-icon
+tags: grid, blazor, filter, highlight, initialization, compositefilterdescriptor
+res_type: kb
+ticketid: 1668133
+---
+
+## Environment
+
+<table>
+    <tbody>
+	    <tr>
+	    	<td>Product</td>
+	    	<td>Grid for Blazor</td>
+                <td>TreeList for Blazor</td>
+	    </tr>
+    </tbody>
+</table>
+
+## Description
+
+When using the TelerikGrid for Blazor, applying a filter programmatically on initialization does not highlight the header filter icon. This behavior is expected when filters are manually applied by the user, indicating which columns are currently filtered.
+
+## Cause
+
+The issue arises due to the direct use of `FilterDescriptor` without wrapping it in a `CompositeFilterDescriptor`. The `CompositeFilterDescriptor` is necessary to group individual filters and ensure the UI reflects the applied filters correctly.
+
+## Solution
+
+To highlight the filter menu icon upon initialization, wrap the filter definitions in a `CompositeFilterDescriptor`. This approach ensures the Grid's UI accurately displays which filters are active.
+
+Below is an example demonstrating how to initialize a Grid with a predefined filter on the "Released" column that highlights the filter icon correctly:
+
+```RAZOR
+@using Telerik.DataSource
+
+<TelerikGrid Data="@GridData"
+             Pageable="true"
+             PageSize="5"
+             Sortable="true"
+             FilterMode="@GridFilterMode.FilterMenu"
+             Groupable="true"
+             OnStateInit="@( (GridStateEventArgs<Product> args) => OnGridStateInit(args) )">
+    <GridColumns>
+        <GridColumn Field="@nameof(Product.Name)" />
+        <GridColumn Field="@nameof(Product.Released)" />
+        <GridColumn Field="@nameof(Product.Discontinued)" />
+    </GridColumns>
+</TelerikGrid>
+
+@code {
+    private List<Product> GridData { get; set; }
+
+    private async Task OnGridStateInit(GridStateEventArgs<Product> args)
+    {
+        var discontinuedColumnFilter = new CompositeFilterDescriptor()
+        {
+            FilterDescriptors = new FilterDescriptorCollection() {
+                new FilterDescriptor()
+                {
+                   Member = "Released",
+                   Operator = FilterOperator.IsLessThan,
+                   Value = DateTime.Today,
+                   MemberType = typeof(DateTime)
+                }
+            }
+        };
+        args.GridState.FilterDescriptors.Add(discontinuedColumnFilter);
+    }
+
+    protected override void OnInitialized()
+    {
+        GridData = new List<Product>();
+        var rnd = new Random();
+
+        for (int i = 1; i <= 12; i++)
+        {
+            GridData.Add(new Product()
+            {
+                Id = i,
+                Name = $"Product {i}",
+                Released = DateTime.Now.AddDays(-rnd.Next(1, 365)).AddYears(-rnd.Next(1, 10)).Date,
+                Discontinued = i % 3 == 0
+            });
+        }
+    }
+
+    public class Product
+    {
+        public int Id { get; set; }
+        public string Name { get; set; }
+        public DateTime Released { get; set; }
+        public bool Discontinued { get; set; }
+    }
+}
+```
+
+## See Also
+
+- [Grid Overview](https://docs.telerik.com/blazor-ui/components/grid/overview)
+- [Grid OnStateInit Event](https://docs.telerik.com/blazor-ui/components/grid/state#onstateinit)