Display hierarchical data with TreeView
Teemu KeiskiVery often
applications have need to manage hierarchical data and indeed such that
hierarchy is unlimited. This has been a bit problem in databases, although
solved using self-referencing tables or alternative solutions. OK, but how to
display such data that uses self-referencing table?
With
ASP.NET one optional answer is to use TreeView control. TreeView gives
developers chance to display hierarchical data as I’ll demonstrate in this
article. What makes TreeView so cool is that it can also display elements (tree
nodes) based on XML.
Overview of
things that developer needs to do to get this feature are:
- Get the data from
self-referencing table into DataSet
- Create DataRelation that
corresponds to relation in self-referencing table and add it to DataSet’s
Relations collection. DataRelation’s Nested property needs to be true.
- Get DataSet’s XML
representation and apply XSLT transformation for it so that result
corresponds to XML syntax used by TreeView control.
- Bind TreeView.
Self-referencing table
Assume that
in database we have table as follows:
