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Control.ResolveUrl Method

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

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

public string ResolveUrl(
	string relativeUrl
)

Parameters

relativeUrl
Type: System.String

The URL associated with the TemplateSourceDirectory property.

Return Value

Type: System.String
The converted URL.

ExceptionCondition
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.

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:Control
{
   private string _ImageUrl;     
   public string ImageUrl
   {
      get
      {
         return _ImageUrl;
      }
      set
      {
         _ImageUrl = value;
      }
   }
   protected override void Render(HtmlTextWriter output)
   {           
      Image myImage = new Image();
      // Resolve Url.
      myImage.ImageUrl = ResolveUrl(this.ImageUrl);
      myImage.RenderControl(output);         
   }     
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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