EF , how to query result of query again

           var schools = entities.Companies.OfType<School>();
                if (hasHSAlumni)
                {
                    schools = (ObjectQuery<School>)schools.Where(p => p.HSGraduateExist == true);
                }

Telerik Report doesnt see custom objects /class using objectDataSource

       public class EventTypeCompanysEvents
        {
            public EventType eventType ;
            public School school ;
            public Event _event ;
        }       
public static List<EventTypeCompanysEvents> GetEventsByType(List<int> eventTypeIDs, List<int> schoolIDs, DateTime startDate, DateTime endDate)
I was getting  "not defined in current context" error ,trying to call
 a method("GetEventsByType" in this case) inside an objectdataSource.
The method is fully working and tested ,yet Telerik Report was not seeing the fields of the
objectDataSource.
Here is the solution:
Convert  members of your custom class to properties:
 public class EventTypeCompanysEvents
        {
            public EventType eventType { get; set; }
            public School school { get; set; }
            public Event _event { get; set; }
        }

 and now you can drag your fields to your report ! 

EF 4 and Membership Provider

Asp.Net's MembershipProvider is very useful. It has builtin user role access system , good encryption features and more. To make it work with EF you need to override MembershipProvider. Here is a project that  to make these two work: http://efmembership.codeplex.com/

I chose to use the older version 1.0 which is for EF 4.0  , the latest one works with EF4.2 and it's Code First and I m not very Code First fan , I prefer  to design so I chose Model First . After downloading the project I had to make changes to make it compile. And I also downloaded another tool which helps a lot using EF.

Normally for every single change you make in the  Model , you need to recreate all the tables or get the DDL  Difference and apply the difference script to database , this tools does detect incremental changes and migrare both schema and data so you wont be losing anything:http://visualstudiogallery.msdn.microsoft.com/df3541c3-d833-4b65-b942-989e7ec74c87
It has some bugs though. After making changes in your datamodel in EF you can create the SQL script to apply changes. I use the Table Per Type instead of Table Per Hierarchy.

 Although both EfRoleProvider and EFMembershipProvider classes in the overridden MEmbershipProvider  contain methods commonly needed, I recreated alternative methods as I don't like the signatures of some .
For example instead of passing/retrieving  string array as RoleNames or User names I want to pass/retrieve List<Object> or Collection of objects. This is the overridden GetRolesForUser method which returns a string array, which I think is very impractical:

    public override string[] GetRolesForUser(string username)

And this is my method which returns Role objects as IList: 

  public static List<Role> GetUsersRoles(string userName)
  {
        User user;
        using (Entities entities = new Entities())
        {
            entities.Connection.Open();
user = entities.Users.Include("Roles").FirstOrDefault(p => p.Username == userName);
        }
 
        if (user != null)
        {
            return user.Roles.ToList();
        }
        else
        {
            return null;
        }
    }

Permanent Fix to "Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information"

I keep getting this "Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information" Every time I had to restart IIS to temporarily fix it. I tried many things to resolve the issue nothing really helped. Finally I have a permanent fix : It's fixed in .Net 4.5 framework You have to install .NEt 4.5 and do nothing else. According to forums 4.5 requires VS 2012 And I m still using 2010