Control.ResolveUrl Method (String)

 

Converts a URL into one that is usable on the requesting client.

Namespace:   System.Web.UI
Assembly:  System.Web (in System.Web.dll)

Public Function ResolveUrl (
	relativeUrl As String
) As String

Parameters

relativeUrl
Type: System.String

The URL associated with the TemplateSourceDirectory property.

Return Value

Type: System.String

The converted URL.

Exception Condition
ArgumentNullException

Occurs if the relativeUrl parameter contains null.

If the relativeUrl parameter contains an absolute URL, the URL is returned unchanged. If the relativeUrl parameter contains a relative URL, that URL is changed to a relative URL that is correct for the current request path, so that the browser can resolve the URL.

For example, consider the following scenario:

  • A client has requested an ASP.NET page that contains a user control that has an image associated with it.

  • The ASP.NET page is located at /Store/page1.aspx.

  • The user control is located at /Store/UserControls/UC1.ascx.

  • The image file is located at /UserControls/Images/Image1.jpg.

If the user control passes the relative path to the image (that is, /Store/UserControls/Images/Image1.jpg) to the ResolveUrl method, the method will return the value /Images/Image1.jpg.

This method uses the TemplateSourceDirectory property to resolve to the absolute URL. The returned URL is for client use.

For more information on resource paths in a Web site, see ASP.NET Web Project Paths.

System_CAPS_noteNote

For mobile Web pages only, if your application relies on cookieless sessions or might receive requests from mobile browsers that require cookieless sessions, using a tilde ("~") in a path can result in inadvertently creating a new session and potentially losing session data. To set a property with a path such as "~/path", resolve the path by calling the ResolveUrl with an argument such as "~/path" before assigning it to the property.

The following example creates an Image Web server control object and uses the ResolveUrl method to set the path to the image, which is stored by the ImageUrl property.

Public Class MyResolveUrl
   Inherits Control
   Private _ImageUrl As String

   Public Property ImageUrl() As String
      Get
         Return _ImageUrl
      End Get
      Set
         _ImageUrl = value
      End Set
   End Property

   Protected Overrides Sub Render(output As HtmlTextWriter)
      Dim myImage As New System.Web.UI.WebControls.Image()
      ' Resolve Url.
      myImage.ImageUrl = ResolveUrl(Me.ImageUrl)
      myImage.RenderControl(output)
   End Sub
End Class

.NET Framework
Available since 1.1
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