How do I find the data type of an AD attribute not having a value

Question

I am struggling to find the data type of AD attributes that are not having a value already. Thus far a resulting DirecoryEntry only contains a property for attributes that already have a value. I can't find a method to obtain information about all other attributes.

Adding a value to the 'PropertiesToLoad' doesn't seem to do anything. The returned DirectoryEntry object contains all attributes (with values) regardless of what is added here.

Code used:

public void Test(string ldapPath)
{
   Type orgType;
   try
   {
     using (DirectoryEntry searchRoot = GetSearchRoot(ldapPath))
     {
        using (DirectorySearcher search = new DirectorySearcher(searchRoot))
        {
            search.Filter = "(&(objectCategory=person)(objectClass=user)(sAMAccountName=coen))";

            search.PropertiesToLoad.Add("msExchHomeServerName");

            SearchResult searchResult = search.FindOne();
            {
                using (DirectoryEntry entry = searchResult.GetDirectoryEntry())
                {
                    if (entry != null)
                    {
                        if (entry.Properties.Contains("msExchHomeServerName"))
                        {
                            orgType = entry.Properties["msExchHomeServerName"].GetType();
                        }
                        else // The value is empty and NOT present in the current 'entry.Properties' object.
                        {
                            throw new Exception("Unknown type");
                        }
                    }
                }
            }
        }
    }
   }
   catch (Exception e)
   {
     <handle exception>
   }
}

Is there a way to find the data type of the 'msExchHomeServerName' (or any of the 'empty' attributes) attribute?

Any help would be highly appreciated!

Coen

Answer 1

Thanks to Damien_The_Unbeliever who pointed me in the right direction, I managed to create the following method:

public Dictionary<string, ActiveDirectorySyntax> GetAttributeSyntaxes(List<string> lstAttributeNames)
{
    Dictionary<string, ActiveDirectorySyntax> dictRes = new Dictionary<string, ActiveDirectorySyntax>();

    if (lstAttributeNames.Count > 0)
    {
        DirectoryContext directoryContext = new DirectoryContext(DirectoryContextType.DirectoryServer,
                                                             m_Server, m_UserName, m_Password);

        using (ActiveDirectorySchema currentSchema = ActiveDirectorySchema.GetSchema(directoryContext))
        {
            using (ActiveDirectorySchemaClass objClass = currentSchema.FindClass("user"))
            {
                if (objClass != null)
                {
                    ReadOnlyActiveDirectorySchemaPropertyCollection propcol = objClass.GetAllProperties();

                    foreach (ActiveDirectorySchemaProperty schemaProperty in propcol)
                    {
                        foreach (string attrName in lstAttributeNames)
                        {
                            if (schemaProperty.Name.Equals(attrName))
                            {                                    
                                dictRes.Add(attrName, schemaProperty.Syntax);

                                break;
                            }
                        }
                    }
                }
            }
        }
    }

    return dictRes;
}

The returned 'schemaProperty.Syntax' contains sufficient information to determine the actual data type.

Thanks Damien!