# Switch in Razor Pages

This article describes how to seamlessly integrate and configure the Telerik UI Switch for ASP.NET Core in Razor Pages applications.

## Referencing Handler Methods in Razor Pages

Razor Pages is an alternative to the MVC pattern that makes page-focused coding easier and more productive. This approach consists of a `cshtml` file and a `cshtml.cs` file (by convention, the two files have the same name).

The `cshtml.cs` file, known as the `PageModel`, contains handler methods that respond to HTTP requests. These methods are prefixed with `On` followed by the HTTP verb (for example, `OnGet`, `OnPost`, `OnPostRead`, `OnPostCreate`).

Handler methods declared in a `PageModel` can be referenced from any Razor Page using one of the following URL patterns:

* Using `Url.Page()`

  ```C#
  Url.Page("PageName", "HandlerName")
  // OR
  Url.Page("/FolderName/PageName", "HandlerName")
  ```

  For example, `Url.Page("Index", "Read")` references the `OnPostRead` or `OnGetRead` handler method in the `Index.cshtml.cs` file.

* Using a query string

  ```C#
  Url("/PathToPage?handler=HandlerName")
  ```

  For example, `Url("/Index?handler=Read")` references the `OnPostRead` or `OnGetRead` handler method in the `Index` page.

For more information on Razor Pages architecture and concepts, refer to [the official Microsoft documentation](https://learn.microsoft.com/en-us/aspnet/core/razor-pages/).

## Binding to a PageModel Property

To bind the Switch to a property from the `PageModel`, follow the next steps:

1. Add a property to the `PageModel` that must bind to the Switch.

   ```C# Index.cshtml.cs
   public class IndexModel : PageModel
   {
       [BindProperty]
       public bool IsChecked { get; set; }

       public void OnGet()
       {
           IsChecked = true;
       }
   }
   ```

2. Declare the `PageModel` at the top of the page.

   ```Razor
       @page
       @model IndexModel
   ```

3. Bind the Switch to the property using the `SwitchFor()` configuration.

   ```Razor HtmlHelper
   @page
   @model IndexModel

   @inject Microsoft.AspNetCore.Antiforgery.IAntiforgery Xsrf
   @Html.AntiForgeryToken()

   @(Html.Kendo().SwitchFor(m => m.IsChecked))
   ```

   ```Razor TagHelper
   @page
   @model IndexModel

   @inject Microsoft.AspNetCore.Antiforgery.IAntiforgery Xsrf
   @Html.AntiForgeryToken()

   <kendo-switch for="IsChecked"></kendo-switch>
   ```

### Binding to a Nested Property

The `for` attribute accepts a model expression, including a nested Boolean property. For example, if the `PageModel` has a `Patient` property with a `NoEmail` property, bind the Switch as follows:

```C# Index.cshtml.cs
public class IndexModel : PageModel
{
    [BindProperty]
    public PatientViewModel Patient { get; set; } = new PatientViewModel();
}

public class PatientViewModel
{
    public bool NoEmail { get; set; }
}
```

```Razor TagHelper
<kendo-switch for="Patient.NoEmail"></kendo-switch>
```

The generated field name is `Patient.NoEmail`, which allows the value to bind to the nested property when the form is submitted. The `SwitchFor` HtmlHelper supports the equivalent expression:

```Razor HtmlHelper
@(Html.Kendo().SwitchFor(m => m.Patient.NoEmail))
```

If a checkbox remains visible instead of being transformed into a Switch, inspect the rendered markup and browser console. The Switch is initialized on a checkbox input, so a visible checkbox can indicate that the Kendo UI scripts or styles are not loaded, the Switch initialization script did not run, or the generated ID is not unique. These checks are separate from the model-binding path.

For the complete project, refer to the [Switch in Razor Pages example](https://github.com/telerik/ui-for-aspnet-core-examples/blob/master/Telerik.Examples.RazorPages/Telerik.Examples.RazorPages/Pages/Switch/SwitchIndex.cshtml).

## See Also

* [Using Telerik UI for ASP.NET Core in Razor Pages](https://docs.telerik.com/aspnet-core/getting-started/razor-pages#using-telerik-ui-for-aspnet-core-in-razor-pages)
* [Client-Side API of the Switch](https://www.telerik.com/kendo-jquery-ui/documentation/api/ui/switch)
* [Server-Side HtmlHelper API of the Switch](https://www.telerik.com/aspnet-core-ui/documentation/api/switch)
* [Server-Side TagHelper API of the Switch](https://www.telerik.com/aspnet-core-ui/documentation/api/taghelpers/switch)
* [Knowledge Base Section](https://www.telerik.com/aspnet-core-ui/documentation/knowledge-base)