The following code example demonstrates how you can handle the SiteMapResolve event on an ASP.NET Web page to modify the target URLs that are displayed by the SiteMapPath control. In this example, the current page is a post page in an online bulletin board or forum. To render more meaningful site navigation, the URLs of the nodes that are displayed by the SiteMapPath control are appended with context-relevant query strings. Use the following code to render the control.
<asp:SiteMapPath
id="SiteMapPath1"
runat="server"
RenderCurrentNodeAsLink="true" />
<asp:SiteMapPath
id="SiteMapPath1"
runat="server"
RenderCurrentNodeAsLink="true" />
When running the example, place your cursor over the links in the SiteMapPath control to see how the URLs are changed.
This example does not add SiteMapNode items in the Web.sitemap file; the Web.sitemap file can only be edited manually.
.gif) Note: |
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It is safe to access the
CurrentNode property from within the SiteMapResolveEventHandler. The ASP.NET site-navigation infrastructure guards against infinite recursion in this case.
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This example assumes that you already have a valid site-map file, and that the current page is at least three nodes deep in the site-map structure. For more information about creating site maps, see ASP.NET Site Maps.
Private Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
' The ExpandForumPaths method is called to handle
' the SiteMapResolve event.
AddHandler SiteMap.SiteMapResolve, AddressOf Me.ExpandForumPaths
End Sub
Private Function ExpandForumPaths(ByVal sender As Object, ByVal e As SiteMapResolveEventArgs) As SiteMapNode
' The current node represents a Post page in a bulletin board forum.
' Clone the current node and all of its relevant parents. This
' returns a site map node that a developer can then
' walk, modifying each node.Url property in turn.
' Since the cloned nodes are separate from the underlying
' site navigation structure, the fixups that are made do not
' effect the overall site navigation structure.
Dim currentNode As SiteMapNode = SiteMap.CurrentNode.Clone(True)
Dim tempNode As SiteMapNode = currentNode
' Obtain the recent IDs.
Dim forumGroupID As Integer = GetMostRecentForumGroupID()
Dim forumID As Integer = GetMostRecentForumID(forumGroupID)
Dim postID As Integer = GetMostRecentPostID(forumID)
' The current node, and its parents, can be modified to include
' dynamic querystring information relevant to the currently
' executing request.
If Not (0 = postID) Then
tempNode.Url = tempNode.Url & "?PostID=" & postID.ToString()
End If
tempNode = tempNode.ParentNode
If Not (0 = forumID) And Not (tempNode Is Nothing) Then
tempNode.Url = tempNode.Url & "?ForumID=" & forumID.ToString()
End If
tempNode = tempNode.ParentNode
If Not (0 = ForumGroupID) And Not (tempNode Is Nothing) Then
tempNode.Url = tempNode.Url & "?ForumGroupID=" & forumGroupID.ToString()
End If
Return currentNode
End Function
...
' These methods are just placeholders for the example.
' One option is to use the HttpContext or e.Content object
' to obtain the ID.
Private Function GetMostRecentForumGroupID() As Integer
Return 24
End Function
Private Function GetMostRecentForumID(ByVal forumGroupId As Integer) As Integer
Return 128
End Function
Private Function GetMostRecentPostID(ByVal forumId As Integer) As Integer
Return 317424
End Function
private void Page_Load(object sender, EventArgs e)
{
// The ExpandForumPaths method is called to handle
// the SiteMapResolve event.
SiteMap.SiteMapResolve +=
new SiteMapResolveEventHandler(this.ExpandForumPaths);
}
private SiteMapNode ExpandForumPaths(Object sender, SiteMapResolveEventArgs e)
{
// The current node represents a Post page in a bulletin board forum.
// Clone the current node and all of its relevant parents. This
// returns a site map node that a developer can then
// walk, modifying each node.Url property in turn.
// Since the cloned nodes are separate from the underlying
// site navigation structure, the fixups that are made do not
// effect the overall site navigation structure.
SiteMapNode currentNode = SiteMap.CurrentNode.Clone(true);
SiteMapNode tempNode = currentNode;
// Obtain the recent IDs.
int forumGroupID = GetMostRecentForumGroupID();
int forumID = GetMostRecentForumID(forumGroupID);
int postID = GetMostRecentPostID(forumID);
// The current node, and its parents, can be modified to include
// dynamic querystring information relevant to the currently
// executing request.
if (0 != postID)
{
tempNode.Url = tempNode.Url + "?PostID=" + postID.ToString();
}
if ((null != (tempNode = tempNode.ParentNode)) &&
(0 != forumID))
{
tempNode.Url = tempNode.Url + "?ForumID=" + forumID.ToString();
}
if ((null != (tempNode = tempNode.ParentNode)) &&
(0 != forumGroupID))
{
tempNode.Url = tempNode.Url + "?ForumGroupID=" + forumGroupID.ToString();
}
return currentNode;
}
...
// These methods are just placeholders for the example.
// One option is to use the HttpContext or e.Content object
// to obtain the ID.
private int GetMostRecentForumGroupID()
{
return 24;
}
private int GetMostRecentForumID(int forumGroupId)
{
return 128;
}
private int GetMostRecentPostID(int forumId)
{
return 317424;
}