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4.8. Add Navigation to Your Site
Most web sites include some type of
navigation bar that lets users move from one page to another. In
ASP.NET 1.0 and 1.1, it's easy enough to create
these navigation controls, but you need to do so by hand. In ASP.NET
2.0, a new sitemap feature offers a much more
convenient pre-built solution. The basic principle is that you define
the structure of your web site in a special XML file. Once
you've taken that step, you can configure a list or
tree control to use the sitemap datagiving you a clickable
navigation control with no code required.
Note: ASP. NET 2.0 provides new navigation features that let you
create a sitemap and bind it to different controls.
4.8.1. How do I do that?
The first step in using ASP.NET's new sitemap
feature is to define the structure of your web site in an XML file
named web.sitemap. To add
this file to your site in Visual Studio, right-click the Solution
Explorer and select Add New Item. Select the Site Map file type and
click Add.The first ingredient you need in the web.sitemap
file is the root <siteMap> tag:
<siteMap>In the <siteMap> tag, you add one
</siteMap>
<siteMapNode> child
element for each entry you want to show in the sitemap. You can then
give a title, description, and URL link for each entry using
attributes. Here's an example:
<siteMapNode title="Home" description="Home Page" url="default.aspx" />Notice that this tag ends with the
characters /> instead of
just >. This indicates that
it's an empty elementin
other words, it doesn't contain any other elements.
However, if you want to build a multi-level sitemap, you have to nest
one <siteMapNode> element inside another.
Here's an example:
<siteMapNode title="Home" description="Home Page" url="default.aspx" >Example 4-5 shows a sitemap with six links in three
<siteMapNode title="Products"
description="Order Products" url="produ.aspx" />
</siteMapNode>
levels.
Example 4-5. A multi-level sitemap
<?xml version="1.0" ?>Once you create a sitemap, it's easy to use it on a
<siteMap>
<siteMapNode title="Home" description="Home" url="default.aspx">
<siteMapNode title="Personal" description="Personal Services"
url="personal.aspx">
<siteMapNode title="Resume" description="Download Resume"
url="resume.aspx" />
</siteMapNode>
<siteMapNode title="Business" description="Business Services"
url="business.aspx">
<siteMapNode title="Products" description="Order Products"
url="products.aspx" />
<siteMapNode title="Contact Us" description="Contact Information"
url="contact.aspx" />
</siteMapNode>
</siteMapNode>
</siteMap>
web page, thanks to the new SiteMapDataSource
control. This control works much like the other data source controls
discussed in "Bind to Data Without Writing
Code." However, it doesn't require
any properties at all. Once you add the
SiteMapDataSource, ASP.NET automatically reads the
web.sitemap file and makes its data available to
your other controls:
<asp:SiteMapDataSource ID="SiteMapDataSource1" Runat="server" />Now you can bind just about any other control to the
SiteMapDataSource. Because sitemaps are, by
default, hierarchical, they work particularly well with the
new
treeView control.
Here's a treeView control that
binds to the sitemap data:
<asp:TreeView ID="TreeView1" Runat="server" DataSourceID="SiteMapDataSource1"The resulting treeView doesn't
Font-Names="Verdana" Font-Size="8pt" ForeColor="Black" ImageSet="BulletedList"
Width="149px" Height="132px">
</asp:TreeView>
just show the sitemap, it also renders each node as a hyperlink that,
if clicked, sends the user to the appropriate page. Figure 4-11 shows a content page that's
based on a master page that uses a treeView with a
sitemap. (Refer to the lab "Achieve a Consistent
Look and Feel with Master Pages" for more
information about master pages.)
Figure 4-11. Using a sitemap in a master page
4.8.2. What about...
...customizing the sitemap? There's a lot more you
can do to control the look of a site as well as its behavior. Here
are some starting points:Show a sitemap in a non-hierarchical control
Controls like the ListBox and
GridView don't support the
sitemap's tree-based view. To solve this problem,
set the SiteMapDataSource.SiteMapViewType
property to Flat instead of
tree so that the multi-layered sitemap is
flattened into a single-level list. You can also use the
Flat option with a TReeView to
save screen real estate (because subsequent levels
won't be indented).
Vary the sitemap displayed in different pages
To accomplish this, put all the sitemap information you need into the
same web.sitemap file, but in different
branches. Then, set the SiteMapDataSource.StartingNodeUrl
to the URL of the page you want to use as the root of your sitemap.
The SiteMapDataSource will only get the data from
that node, and all the nodes it contains.
Make the sitemap collapsible
If you have a large sitemap, just set
the TReeView.ShowExpandCollapse to
TRue, and the familiar plus boxes will appear next
to Home, Personal, and Business, allowing you to show just part of
the sitemap at a time.
Fine-tune the appearance of the TreeView
It's remarkably easy.
In the previous example, the treeView used the
bullet style, which shows different bullet icons next to each item.
By setting the treeView.ImageSet to different
values available within the treeViewImageSet
enumeration, you can show square bullets, arrows, folder and file
icons, and much more. For even more information about tweaking the
treeView (or using it in other scenarios that
don't involve sitemaps), look up the reference for
the System.Web.UI.WebControls.TreeView
class.
Retrieve the sitemap information from another location
Maybe you want to store your sitemap in a different file, a database,
or some other data source. Unfortunately, the
SiteMapProvider doesn't have the
ability to retrieve information from these locationsat least
not yet. Instead, you'll need to create your own
custom sitemap provider. Refer to the MSDN help under the index entry
"site map."
