docs(grid): Update Grid search in hidden fields KB (#1303)

Co-authored-by: Dimo Dimov <[email protected]>

Author: github-actions[bot]

knowledge-base/grid-search-in-hidden-fields.md

@@ -5,19 +5,20 @@ type: how-to
 page_title: Search in hidden fields of the Grid
 slug: grid-kb-search-in-hidden-fields
 position: 
-tags: telerik,blazor,grid,search,searchbox,hidden,field,column,not,visible
+tags: telerik, blazor, grid, search, searchbox
 ticketid: 1540910
 res_type: kb
 ---
 
 ## Environment
+
 <table>
-	<tbody>
-		<tr>
-			<td>Product</td>
-			<td>Grid for Blazor</td>
-		</tr>
-	</tbody>
+    <tbody>
+        <tr>
+            <td>Product</td>
+            <td>Grid for Blazor</td>
+        </tr>
+    </tbody>
 </table>
 
 
@@ -31,24 +32,24 @@ By default, the Grid looks in all string fields in its currently visible columns
 
 If you want to search in the hidden fields of the Grid, do the following:
 
-* Use the Grid with an [OnRead handler]({%slug components/grid/manual-operations%}).
-* In the OnRead handler, [check if there is a filter applied]({%slug components/grid/manual-operations%}#get-information-from-the-datasourcerequest).
-* The applied filter must be of type [CompositeFilterDescriptor](https://docs.telerik.com/blazor-ui/api/Telerik.DataSource.CompositeFilterDescriptor). Plain `FilterDescriptors` at root level (`args.Request.Filters`) are generated by the filter row. The composite filter descriptor has a `FilterDescriptors` property, which holds a collection plain [single-field FilterDescriptors](https://docs.telerik.com/blazor-ui/api/Telerik.DataSource.FilterDescriptor). Each of them targets one of the visible columns.
-* Obtain the search string from the `Value` property of any of the descriptors in the above collection.
-* Add one additional `FilterDescriptor` to the above collection that targets the hidden column.
+* Bind the Grid with an [`OnRead` event handler]({%slug common-features-data-binding-onread%}).
+* In the `OnRead` handler, [check if there is a filter applied]({%slug components/grid/manual-operations%}#get-information-from-the-datasourcerequest) in `args.Request.Filters`.
+* The applied filters are of type [`CompositeFilterDescriptor`](https://docs.telerik.com/blazor-ui/api/Telerik.DataSource.CompositeFilterDescriptor). The composite filter descriptor has a `FilterDescriptors` property, which holds a collection plain [single-field `FilterDescriptor`s](https://docs.telerik.com/blazor-ui/api/Telerik.DataSource.FilterDescriptor). Each of the `FilterDescriptor` in the search descriptor targets one of the visible columns.
+* Obtain the search string from the `SearchFilter` property of the Grid state. It holds a `CompositeFilterDescriptor` too.
+* Add one additional `FilterDescriptor` to the search `CompositeFilterDescriptor` for every hidden column.
 
-Here is an example:
+>caption Search in hidden Grid columns
 
 ````CSHTML
 @using Telerik.DataSource.Extensions
 @using Telerik.DataSource
 
-<TelerikGrid TItem="@GridItem"
-             OnRead="@GridReadHandler"
+<TelerikGrid @ref="@GridRef"
+             TItem="@GridItem"
+             OnRead="@OnGridRead"
              FilterMode="@GridFilterMode.FilterRow">
     <GridToolBarTemplate>
         <strong style="color:#900">Search for "secret#", where # is the ID number:</strong>
-        <span class="k-toolbar-spacer"></span>
         <GridSearchBox DebounceDelay="200"></GridSearchBox>
     </GridToolBarTemplate>
     <GridColumns>
@@ -59,40 +60,57 @@ Here is an example:
 </TelerikGrid>
 
 @code {
-    public List<GridItem> GridData { get; set; } = new List<GridItem>();
+    private TelerikGrid<GridItem> GridRef { get; set; }
+
+    private List<GridItem> GridData { get; set; }
 
-    private async Task GridReadHandler(GridReadEventArgs args)
+    private async Task OnGridRead(GridReadEventArgs args)
     {
         // check if we have any filtering at all
         if (args.Request.Filters.Count > 0)
         {
-            foreach (var rootFilterDescriptor in args.Request.Filters)
+            // get the search string from the Grid state
+            var searchDescriptor = (CompositeFilterDescriptor)GridRef.GetState().SearchFilter;
+            var searchString = (searchDescriptor?.FilterDescriptors[0] as FilterDescriptor)?.Value.ToString();
+
+            if (!string.IsNullOrEmpty(searchString))
             {
-                // row filters are FilterDescriptors; search and menu filters are CompositeFilterDescriptors
-                if (rootFilterDescriptor.GetType() == typeof(CompositeFilterDescriptor))
+                // locate the search filter descriptor among all others in the request
+                // if Grid filtering is disabled, then args.Request.Filters will contain only the search descriptor
+                foreach (var rootFilterDescriptor in args.Request.Filters)
                 {
-                    var searchDescriptor = rootFilterDescriptor as CompositeFilterDescriptor;
-                    var searchString = (searchDescriptor.FilterDescriptors[0] as FilterDescriptor).Value.ToString();
+                    // in versions 3.x: row filters are FilterDescriptors; search and menu filters are CompositeFilterDescriptors
+                    // in versions 4.x: all filters are CompositeFilterDescriptors
+                    var filterDescriptor = rootFilterDescriptor as CompositeFilterDescriptor;
+                    var filterString = (searchDescriptor.FilterDescriptors[0] as FilterDescriptor).Value.ToString();
 
-                    // add a descriptor for each hidden column that you want to search in
-                    searchDescriptor.FilterDescriptors.Add(new FilterDescriptor()
+                    if (searchString == filterString)
                     {
-                        Member = "Secret",
-                        MemberType = typeof(string),
-                        Value = searchString,
-                        Operator = FilterOperator.Contains
-                    });
+                        // add a descriptor for each hidden column that you want to search in
+                        filterDescriptor.FilterDescriptors.Add(new FilterDescriptor()
+                        {
+                            Member = "Secret",
+                            MemberType = typeof(string),
+                            Value = searchString,
+                            Operator = FilterOperator.Contains
+                        });
+
+                        break;
+                    }
                 }
             }
         }
 
         var result = GridData.ToDataSourceResult(args.Request);
+
         args.Data = result.Data;
         args.Total = result.Total;
     }
 
     protected override Task OnInitializedAsync()
     {
+        GridData = new List<GridItem>();
+
         for (int j = 1; j <= 10; j++)
         {
             GridData.Add(new GridItem() { ID = j, Name = "Name " + j, Secret = "Secret" + j });