WebView.AddWebAllowedObject(String, Object) Method

Definition

Namespace:

Windows.UI.Xaml.Controls

Adds a native Windows Runtime object as a global parameter to the top level document inside of a WebView.

public:
 virtual void AddWebAllowedObject(Platform::String ^ name, Platform::Object ^ pObject) = AddWebAllowedObject;

void AddWebAllowedObject(winrt::hstring const& name, IInspectable const& pObject);

public void AddWebAllowedObject(string name, object pObject);

function addWebAllowedObject(name, pObject)

Public Sub AddWebAllowedObject (name As String, pObject As Object)

Parameters

name

String

Platform::String

winrt::hstring

The name of the object to expose to the document in the WebView.

pObject

Object

Platform::Object

IInspectable

The object to expose to the document in the WebView.

Examples

This example shows how to decorate a class with the AllowForWeb attribute.

using Windows.Foundation.Metadata;

namespace MyRuntimeComponent
{
    [AllowForWeb]
    public sealed class MyNativeClass
    {
        public void NativeMethod()
        {
            ...
        }

        ...
    }
}

This example demonstrates using the NavigationStarting event to inject an object when navigation begins.

<WebView x:Name="webView" Source="https://www.contoso.com/index.html"
         NavigationStarting="webView_NavigationStarting"/>

private void webView_NavigationStarting(WebView sender, WebViewNavigationStartingEventArgs args) 
{ 
    if (args.Uri.Host == "www.contoso.com")  
    { 
        webView.AddWebAllowedObject("nativeObject", new MyNativeClass()); 
    } 
} 

Here's how to access the native object in a script in the web page.

<script type='text/javascript'>
    nativeObject.nativeMethod(); // Call the projected WinRT method.
</script>

Remarks

Use this method to expose a native Windows Runtime object as a global parameter in the context of the top level document inside of a WebView. For a Windows Runtime object to be projected, it must agile and be decorated with the AllowForWeb attribute.

Note

Runtime classes created using Microsoft Visual Basic, C# or Visual C++ component extensions (C++/CX) are agile by default. For more info, see Threading and Marshaling and Using Windows Runtime objects in a multithreaded environment.

The object passed into AddWebAllowedObject must be imported from a Windows Runtime component that is separate from the app assembly. This is necessary for the AllowForWeb attribute to be property identified by the WebView security subsystem. If you use a class from your app project, AddWebAllowedObject does not work.

You must call AddWebAllowedObject every time WebView is navigated to a new page that accesses the native object. You can use the WebView.NavigationStarting event to inject the object when navigation begins.