kb(Grid): prevent checkbox column click

Author: IvanDanchev

knowledge-base/grid-checkbox-column-prevent-click.md

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+---
+title: Grid CheckBox column prevent accidental click
+description: How to prevent an accidental click in the CheckBox column of the Grid
+type: how-to
+page_title: Grid CheckBox column prevent accidental click
+slug: grid-checkbox-column-prevent-click
+position: 
+tags: 
+res_type: kb
+---
+
+## Environment
+
+<table>
+    <tbody>
+        <tr>
+            <td>Product</td>
+            <td>Grid for Blazor</td>
+        </tr>
+    </tbody>
+</table>
+
+
+## Description
+
+An accidental click outside the checkbox in the Grid's CheckBox column deselects the currently selected rows. How to prevent that from happening and ensure that only a click on the checkbox deselects the respective row?
+
+## Solution
+
+You can prevent the click event of the cells in the CheckBox column of the Grid with JavaScript. 
+
+1. Handle the `OnRowClick` event of the Grid and call a JavaScript function in it.
+2. In the function, attach a `click` event handler to the `td` Html elements in the CheckBox column and prevent the event conditionally
+
+```razor
+@inject IJSRuntime JS;
+
+<TelerikGrid Data="@GridData"
+             SelectionMode="@GridSelectionMode.Multiple"
+             SelectedItems="@SelectedEmployees"
+             OnRowClick="@OnRowClickHandler"
+             Pageable="true">
+    <GridColumns>
+        <GridCheckboxColumn SelectAll="true" CheckBoxOnlySelection="false" />
+        <GridColumn Field="@nameof(Employee.Name)" />
+        <GridColumn Field="@nameof(Employee.Team)" />
+    </GridColumns>
+</TelerikGrid>
+
+<script suppress-error="BL9992">
+    function handleDeselection() {
+        setTimeout(function() {
+            preventDeselection()
+        }, 300)
+
+    }
+
+    function preventClickHandler(event) {
+        if (event.target === event.currentTarget) {
+            event.preventDefault();
+            event.stopPropagation();
+        }
+    }
+
+    function preventDeselection() {
+        document.querySelectorAll('.k-grid-content .k-table-row td:first-child').forEach(function(td) {
+            td.addEventListener('click', preventClickHandler, true);
+        });
+    }
+</script>
+
+@code {
+    private List<Employee> GridData { get; set; } = new();
+
+    private IEnumerable<Employee> SelectedEmployees { get; set; } = Enumerable.Empty<Employee>();
+
+    private string SelectedItemsChangedLog { get; set; } = string.Empty;
+
+    private async Task OnRowClickHandler(GridRowClickEventArgs args)
+    {
+        // call a function that will prevent deselection of already selected rows
+        await JS.InvokeVoidAsync("handleDeselection");
+    }
+
+
+    protected override void OnInitialized()
+    {
+        for (int i = 1; i <= 15; i++)
+        {
+            GridData.Add(new Employee()
+            {
+                EmployeeId = i,
+                Name = $"Employee {i}",
+                Team = $"Team {i % 3 + 1}"
+            });
+        }
+
+        SelectedEmployees = new List<Employee>() { GridData.ElementAt(2) };
+    }
+
+    public class Employee
+    {
+        public int EmployeeId { get; set; }
+        public string Name { get; set; } = string.Empty;
+        public string Team { get; set; } = string.Empty;
+    }
+}
+```