Hi

I have a sitemapprovider that retreives categorydata from a database. The thing is that I need it to retreive data depending on three parameters. One is a querystring parameter and the two other are taken from values stored in cache. But as it is now, I get the same data no matter what. So I guess it get cache somewhere and that ok, untill any of my three parameters get changed then I want it to refresh the data. Or if the querystring parameter is missing it shouldn't show anything.

Maybe a little blury, but I hope you understand and know what I can do about it.

The code is a modified version of Jeff Prosises SqlSiteMapProvider.

public class SqlSiteMapProvider : StaticSiteMapProvider
    {
        static readonly string _errmsg1 = "Missing store ID";
        SiteMapNode _root = null;
        string _connect;

        public override void Initialize(string name, NameValueCollection attributes)
        {
            base.Initialize(name, attributes);

            if (attributes == null)
                throw new ConfigurationErrorsException(_errmsg1);

            _connect = Global.ConnectionString();

        }

        [MethodImpl(MethodImplOptions.Synchronized)]
        public override SiteMapNode BuildSiteMap()
        {
            HttpContext context = HttpContext.Current;
            int storeid = Convert.ToInt32(context.Request.QueryString["s"]); //TODO: validation
            int lingo1 = Lingo.GetDefault();
            int lingo2 = Lingo.GetSecondary();

            // Return immediately if this method has been called before
            if (_root != null) return _root;

            // Create a dictionary for temporary node storage and lookup
            Dictionary<int, SiteMapNode> nodes = new Dictionary<int, SiteMapNode>();
           

            // Query the database for site map nodes
            using(SqlConnection connection = new SqlConnection(_connect))
            {
                connection.Open();
               
                SqlCommand command = new SqlCommand("up_CategorySelectByStore", connection);
                command.CommandType = CommandType.StoredProcedure;
                command.Parameters.Add("@storeid", SqlDbType.Int).Value = storeid;
                command.Parameters.Add("@lingo2", SqlDbType.Int).Value = lingo2;
                command.Parameters.Add("@lingo1", SqlDbType.Int).Value = lingo1;

                SqlDataReader reader = command.ExecuteReader();

                int id = reader.GetOrdinal("Id");
                int parent = reader.GetOrdinal("Parent");
                int url = reader.GetOrdinal("Url");
                int title = reader.GetOrdinal("Title");
                int desc = reader.GetOrdinal("Desc");     

                if (reader.Read())
                {
                    _root = new SiteMapNode(this, "0", "default.aspx", "Root");
                    nodes.Add(0, _root);
                    AddNode(_root, null);

                    while (reader.Read())
                    {
                        SiteMapNode node = new SiteMapNode(this,
                          reader.GetInt32(id).ToString(), reader.GetString(url),
                          reader.GetString(title), reader.IsDBNull(desc) ?
                              "" : reader.GetString(desc));

                        int parentid = reader.IsDBNull(parent) ? 0 : reader.GetInt32(parent);
                        SiteMapNode parentnode = nodes[parentid];

                        nodes.Add(reader.GetInt32(id), node);

                        AddNode(node, parentnode);
                    }
                }
            }
            return _root;
        }

        protected override SiteMapNode GetRootNodeCore()
        {
            BuildSiteMap();
            return _root;
        }
    }

Ok, there were some other threads dealing with the cache thing and a solution was to override the Clear method like below and it seems to work.

protected override void Clear()
{
   base.Clear();
   this._root = null;
}

But I have the problem of when the Clear method should be called. What I need to do is to check if the values from the previous request are the same as the current request. But what/where is the best place to store the values from the previous request?

protected override SiteMapNode GetRootNodeCore()
{
   if (CheckIfSiteMapShouldBeReloaded())
      this.Clear();

   BuildSiteMap();

   return _root;
}

private bool CheckIfSiteMapShouldBeReloaded()
{
   //Check if any of the three parameters are the same on this request

   return true;
}

DiCoo,

Please read my additions to this post:  http://forums.asp.net/1152721/ShowPost.aspx .  There will be issues with your current implementation.  I think you should also realize that you're going to have contention if two users hit the site simultaneously that both need the SiteMap rebuilt.  The provider is not a single instance and the data is shared between all sessions. 
--
Danny

Thanks for your answer.

I also looked at Dave Sussmans provider that he links to in this thread http://forums.asp.net/971372/ShowPost.aspx. And that code seems to deal with the issues you mention so I will go and rebuild/extend mine on top of that one.

Can also make a request to you Danny or anyone else on the asp.net team. Please build a sitemapprovider that work against a database but have the best-practice of everything in it.

So instead of have to answer the same question about this over and over agian, you will trust me, you can just guide people to the code of that sqlsitemapprovider and everyone can customize that code accoring to the needs they have.

Have now put something together and it looks something like this. My main problem still remains tough. Depending on three parameters so may the SiteMap show/retreive different nodes on each request.

Parameter 1: A querystring. If missing the SiteMap shouldn't show anything.
Parameter 2: A value from cache, different value depending on Parameter 1.
Parameter 3: A value from cache, different value depending on Parameter 1 and a Profile (allowAnonymous="true") value.

If any of these parameters are different from one request to another it should retreive a different set of nodes.

The problem: what the hell am I suppose to do to make this work?

[AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
public class SqlSiteMapProvider : StaticSiteMapProvider
{
   #region Properties
   private int _lingo1 = 124; // Temp value
   private int _lingo2 = 56; // Temp value
   private int _storeid;

   public int StoreId
   {
      get { return _storeid; }
      set { _storeid = value; }
   }

   public int Lingo1
   {
      get { return _lingo1; }
      set { _lingo1 = value; }
   }

   public int Lingo2
   {
      get { return _lingo2; }
      set { _lingo2 = value; }
   }
   #endregion

   #region Private fields
   private string _connectionstring;
   private SiteMapNode _rootnode = null;
   private Dictionary<int, SiteMapNode> _nodes;
   private bool _initialized = false;
   #endregion

   public override void Initialize(string name, NameValueCollection attributes)
   {
      if(_initialized)
         return;
  
      base.Initialize(name, attributes);

      _connectionstring = Global.ConnectionString();

      if (String.IsNullOrEmpty(_connectionstring))
         throw new Exception("The connection string was not found for use in SqlSiteMapProvider.");

      _nodes = new Dictionary<int, SiteMapNode>();

      _initialized = true;
   }

   protected override SiteMapNode GetRootNodeCore()
   {
      BuildSiteMap();
      return _rootnode;
   }

   protected override void Clear()
   {
      lock (this)
      {
         _rootnode = null;
         base.Clear();
      }
   }

   [MethodImpl(MethodImplOptions.Synchronized)]
   public override SiteMapNode BuildSiteMap()
   {
      // Since the SiteMap class is static, make sure that it is
      // not modified while the sitemap is built.
      lock (this)
      {
         // Return immediately if this method has been called before
         if (_rootnode != null)
            return _rootnode;

         // Start with a clean slate
         Clear();

         // Query the database for site map nodes
         using (SqlConnection connection = new SqlConnection(_connectionstring))
         {
            SqlCommand command = new SqlCommand("up_CategorySelectByStore", connection);
            command.CommandType = CommandType.StoredProcedure;
            command.Parameters.Add("@storeid", SqlDbType.Int).Value = StoreId;
            command.Parameters.Add("@lingo1", SqlDbType.Int).Value = Lingo1;
            command.Parameters.Add("@lingo2", SqlDbType.Int).Value = Lingo2;

            connection.Open();

DiCoo,

  What you are trying to do is a quite advanced scenario and not easily supported by the out-of-the-box providers.  The StaticSiteMapProvider was designed to store per-application data and you need to store for per-user data.  I think you will find many more difficult issues and bugs to solve with the code you have shown such as concurrency issues and poor performance due to thrashing of your data store with this approach. 
  What you should do is create your own custom SiteMapProvider starting from the SiteMapProvider base.  The biggest issue you need to solve first is how to store the individual users SiteMap data.  One candidate is in session state, another candidate is in application cache.  The next step after you've come up with a storage method for per-user sitemap data is to populate that data.  Most of the BuildSiteMap code you've shown should transfer easily.  Finally, come up with a method that tests whether the data should be rebuilt.  You can add that test to the beginning of BuildSiteMap along side the is rootNode null test.
--
Danny

Thanks for your input, its much appreciated.

I got some ideas now on how to make it work (in theory anyway. ) I think the cache can be a good place for storage, just have to move some logic from the database to the code. 
Well, you got me thinking...

Also like to say thank you for your blog post on this subject.

Have started building my provider now but found something that puzzled me. Am looking at three providers to get an idea on how to build mine and saw that all thee have three different object they lock to.
 
SDK documentations Text Site-Map Provider: lock(this)
   (url = http://msdn2.microsoft.com/library/ms178433(en-us,vs.80).aspx)
XmlSiteMapProvider: lock(base._lock)
Dannys blog example: lock(_lockObj)

So whats the difference between them? And which one should be used?

#2 and #3 are equivelent because the _lock in the base of XmlSiteMapProvider is declared very similarly to how I do it. 

With respect to #1, I don't use this method although in theory it seems like it should work.  I once read an article that had a very compelling reason why lock(this) wasn't a good idea and it stuck.  Unfortunately I don't remember where I read it so I don't have a good reason to offer you.  But now, out of habit, I create a new object instance and use it for my critical sections. 

--
Danny