VB.NET SQL-powered Sitemap

Hi guys,

So the ever-lasting problem has remained until now - how to create a dynamic sitemap from information stored in a database.

Microsoft's MSDN magazine covered how to do this using a custom-made class in C#, specific table architecture and a couple of database triggers (plus how to deal with caching on SQL Server 7 and 2000 - MSSQL 2K5 automatically deals with cache dependencies which handles new sitemap layout and/or content, which is funky). The article can be found here.

However, I don't work with C#, I work in VB and VB.NET - so I have no idea what any of this code reads, and not only that, but all my sites and custom apps (and future shrink-wrap product line) run in VB/VB.NET - and my understanding is that each project can only work in one language. So how do I take advantage of this great new piece of kit?

Sanjay Uttam translated the entire piece of code from C# to VB.NET - and it does exactly what it says on the tin - creates a sitemap that ASP.NET's SiteMap functionality can work with, so you can link it to TreeView, Menu and SiteMapPath controls, and dynamically update the SiteMap content by storing the information in any SQL relational database structure.

Sanjay's original article can be found here, many thanks to him for taking the time and effort to make a wonderful piece of kit even more accessible and useful to countless numbers of developers worldwide.

The only edit I have made is in the ReplaceNullRefs function at line 242 - in Sanjay's article the function is checking the field index integer itself for null value, and returning the integer itself, not the data in the field that the integer points to.


Code: ( vbnet )


Imports System
Imports System.Web
Imports System.Data.SqlClient
Imports System.Collections.Specialized
Imports System.Configuration
Imports System.Web.Configuration
Imports System.Collections.Generic
Imports System.Configuration.Provider
Imports System.Security.Permissions
Imports System.Data.Common
Imports System.Data
Imports System.Web.Caching

<SqlClientPermission(SecurityAction.Demand, Unrestricted:=True)> _
Public Class SqlSiteMapProvider
Inherits StaticSiteMapProvider

Private Const _errmsg1 As String = "Missing node ID"
Private Const _errmsg2 As String = "Duplicate node ID"
Private Const _errmsg3 As String = "Missing parent ID"
Private Const _errmsg4 As String = "Invalid parent ID"
Private Const _errmsg5 As String = "Empty or missing connectionStringName"
Private Const _errmsg6 As String = "Missing connection string"
Private Const _errmsg7 As String = "Empty connection string"
Private Const _errmsg8 As String = "Invalid sqlCacheDependency"
Private Const _cacheDependencyName As String = "__SiteMapCacheDependency"

Private _connect As String
' Database connection string

Private _database As String, _table As String
' Database info for SQL Server 7/2000 cache dependency

Private _2005dependency As Boolean = False
' Database info for SQL Server 2005 cache dependency

Private _indexID As Integer, _indexTitle As Integer, _indexUrl As Integer, _indexDesc As Integer, _indexRoles As Integer, _indexParent As Integer
Private _nodes As New Dictionary(Of Integer, SiteMapNode)(16)
Private ReadOnly _lock As New Object()
Private _root As SiteMapNode

'Added...Declare an arraylist to hold all the roles this menu item applies to
Public roles As New ArrayList

Public Overloads Overrides Sub Initialize(ByVal name As String, ByVal config As NameValueCollection)
' Verify that config isn't null
If config Is Nothing Then
Throw New ArgumentNullException("config")
End If

' Assign the provider a default name if it doesn't have one
If [String].IsNullOrEmpty(Name) Then
Name = "SqlSiteMapProvider"
End If

' Add a default "description" attribute to config if the
' attribute doesnt exist or is empty
If String.IsNullOrEmpty(config("description")) Then
config.Remove("description")
config.Add("description", "SQL site map provider")
End If

' Call the base class's Initialize method
MyBase.Initialize(Name, config)

' Initialize _connect
Dim connect As String = config("connectionStringName")

If [String].IsNullOrEmpty(connect) Then
Throw New ProviderException(_errmsg5)
End If
config.Remove("connectionStringName")

If WebConfigurationManager.ConnectionStrings(connect) Is Nothing Then
Throw New ProviderException(_errmsg6)
End If

_connect = WebConfigurationManager.ConnectionStrings(connect) .ConnectionString

If [String].IsNullOrEmpty(_connect) Then
Throw New ProviderException(_errmsg7)
End If

' Initialize SQL cache dependency info
Dim dependency As String = config("sqlCacheDependency")

If Not [String].IsNullOrEmpty(dependency) Then
If [String].Equals(dependency, "CommandNotification", StringComparison.InvariantCultureIgnoreCase) Then
SqlDependency.Start(_connect)
_2005dependency = True
Else
' If not "CommandNotification", then extract database and table names
Dim info As String() = dependency.Split(New Char() {":"c})
If info.Length <> 2 Then
Throw New ProviderException(_errmsg8)
End If

_database = info(0)
_table = info(1)
End If

config.Remove("sqlCacheDependency")
End If

' SiteMapProvider processes the securityTrimmingEnabled
' attribute but fails to remove it. Remove it now so we can
' check for unrecognized configuration attributes.

If config("securityTrimmingEnabled") IsNot Nothing Then
config.Remove("securityTrimmingEnabled")
End If

' Throw an exception if unrecognized attributes remain
If config.Count > 0 Then
Dim attr As String = config.GetKey(0)
If Not [String].IsNullOrEmpty(attr) Then
Throw New ProviderException("Unrecognized attribute: " + attr)
End If
End If
End Sub

Public Overloads Overrides Function BuildSiteMap() As SiteMapNode
SyncLock _lock
' Return immediately if this method has been called before
If _root IsNot Nothing Then
Return _root
End If

' Query the database for site map nodes
Dim connection As New SqlConnection(_connect)

Try
Dim command As New SqlCommand("proc_GetSiteMap", connection)
command.CommandType = CommandType.StoredProcedure

' Create a SQL cache dependency if requested
Dim dependency As SqlCacheDependency = Nothing

If _2005dependency Then
dependency = New SqlCacheDependency(command)
ElseIf Not [String].IsNullOrEmpty(_database) AndAlso Not String.IsNullOrEmpty(_table) Then
dependency = New SqlCacheDependency(_database, _table)
End If

connection.Open()
Dim reader As SqlDataReader = command.ExecuteReader()
_indexID = reader.GetOrdinal("ID")
_indexUrl = reader.GetOrdinal("Url")
_indexTitle = reader.GetOrdinal("Title")
_indexDesc = reader.GetOrdinal("Description")
_indexRoles = reader.GetOrdinal("Roles")
_indexParent = reader.GetOrdinal("Parent")

If reader.Read() Then
' Create the root SiteMapNode and add it to the site map

_root = CreateSiteMapNodeFromDataReader(reader)
AddNode(_root, Nothing)

' Build a tree of SiteMapNodes underneath the root node
While reader.Read()
' Create another site map node and add it to the site map
Dim node As SiteMapNode = CreateSiteMapNodeFromDataReader(reader)
AddNode(node, GetParentNodeFromDataReader(reader))
End While

' Use the SQL cache dependency
If dependency IsNot Nothing Then
HttpRuntime.Cache.Insert(_cacheDependencyName, New Object(), dependency, Cache.NoAbsoluteExpiration, Cache.NoSlidingExpiration, CacheItemPriority.NotRemovable, _
New CacheItemRemovedCallback(AddressOf OnSiteMapChanged))
End If
End If
Finally
connection.Close()
End Try

' Return the root SiteMapNode
Return _root
End SyncLock
End Function

Protected Overloads Overrides Function GetRootNodeCore() As SiteMapNode
SyncLock _lock
BuildSiteMap()
Return _root
End SyncLock
End Function

' Helper methods
Private Function CreateSiteMapNodeFromDataReader(ByVal reader As DbDataReader) As SiteMapNode

' Make sure the node ID is present
If reader.IsDBNull(_indexID) Then
Throw New ProviderException(_errmsg1)
End If

' Get the node ID from the DataReader
Dim id As Integer = reader.GetInt32(_indexID)

' Make sure the node ID is unique
If _nodes.ContainsKey(id) Then
Throw New ProviderException(_errmsg2)
End If

' Get title, URL, description, and roles from the DataReader
Dim title As String = ReplaceNullRefs(reader, _indexTitle)
Dim url As String = ReplaceNullRefs(reader, _indexUrl)

'Eliminated...see http://weblogs.asp.net/psteele/archive/2003/10/09/31250.aspx
Dim description As String = ReplaceNullRefs(reader, _indexDesc)

'Changed variable name from 'roles' to 'rolesN' and added line 230 to dump all roles into an arrayList
Dim rolesN As String
Select Case reader.IsDBNull(_indexRoles)
Case True
rolesN = Nothing
Case Else
rolesN = reader(_indexRoles).ToString.Trim()
End Select

Dim rolelist As String()
rolelist = Nothing
If String.IsNullOrEmpty(rolesN) Then
Else
rolelist = rolesN.Split(New Char() {","c, ";"c}, 512)
End If

If IsArray(rolelist) Then
roles = ArrayList.Adapter(rolelist)
End If

' Create a SiteMapNode
Dim node As New SiteMapNode(Me, id.ToString(), url, title, description, rolelist, Nothing, Nothing, Nothing)

' Record the node in the _nodes dictionary
_nodes.Add(id, node)

' Return the node
Return node
End Function

Private Function ReplaceNullRefs(ByVal rdr As SqlDataReader, ByVal rdrVal As Integer) As String
If Not (rdr.IsDBNull(rdrVal)) Then
Return rdr(rdrVal)
Else
Return String.Empty
End If
End Function

Private Function GetParentNodeFromDataReader(ByVal reader As DbDataReader) As SiteMapNode
' Make sure the parent ID is present
If reader.IsDBNull(_indexParent) Then
'**** Commented out throw, added exit function ****
'Throw New ProviderException(_errmsg3)
Exit Function
End If
' Get the parent ID from the DataReader
Dim pid As Integer = reader.GetInt32(_indexParent)

' Make sure the parent ID is valid
If Not _nodes.ContainsKey(pid) Then
Throw New ProviderException(_errmsg4)
End If

' Return the parent SiteMapNode
Return _nodes(pid)
End Function

Private Sub OnSiteMapChanged(ByVal key As String, ByVal item As Object, ByVal reason As CacheItemRemovedReason)
SyncLock _lock
If key = _cacheDependencyName AndAlso reason = CacheItemRemovedReason.DependencyChanged Then
' Refresh the site map
Clear()
_nodes.Clear()
_root = Nothing
End If
End SyncLock
End Sub
End Class

Hope you all find it as useful as I have!