asp.net mvc - MVC error path cannot be null -

i have 2 questions: 1) list of record database , displaying on index page table. error: additional information: argument 'path' cannot null, empty or contain white space. controller:

        public actionresult index()     {         records m = new records();         var records = db.records .include((m.types).tostring());         return view(records .tolist());     } 

in modal:

public partial class records  {     public int id { get; set; }     public nullable<int> types{ get; set; }     public nullable<system.datetime> date { get; set; }  } 

2) have created models database using .edmx file, apply validation above fields. can [required]public nullable<int> types{ get; set; } etc... future if decide change database , perform update .edmx file [require] labels gone. how solve problem'
route config file

public class routeconfig {     public static void registerroutes(routecollection routes)     {         routes.ignoreroute("{resource}.axd/{*pathinfo}");          routes.maproute(             name: "default",             url: "{controller}/{action}/{id}",             defaults: new { controller = "home", action = "index", id = urlparameter.optional }         );     } } 

part one: working out details in comments above

---

as far validation, it's idea establish separate models used through mvc , not pass database models. lot of times may one-to-one, it's not (keep secure information out of wrong hands). said, there libraries automapper make easy (thankfully). example, given model:

public partial class records  {     public int id { get; set; }     public nullable<int> types{ get; set; }     public nullable<system.datetime> date { get; set; } } 

you can create view model:

public class recordsviewmodel {     [required, hiddeninput]     public int id { get; set; }     [required, range(1,100)]     public nullable<int> types{ get; set; }     [required, datatype(datatypes.datetime)]     public nullable<system.datetime> date { get; set; } } 

then map them using like:

records m = new records(); var records = db.records .include((m.types).tostring()); ilist<recordsviewmodel> = mapper.map<ilist<recordsviewmodel>>(records); return view(recordsviewmodel);