System.Data.Entity.ModelConfiguration.ModelValidationException' occurred in EntityFramework.dll in c# consol application -

i new in entityframework , start code, not know why got exception handler "system.data.entity.modelconfiguration.modelvalidationexception' occurred in entityframework.dll" in line var count = context.albums.count();

    using system;     using system.collections.generic;     using system.linq;     using system.text;     using system.threading.tasks;     using system.data.entity;      namespace entityframework1       {         class program          {            static void main(string[] args)             {               using (var context = new musicalbumcontext())                  {                       var count = context.albums.count();                       console.writeline(count);                       context.albums.add(new album() { name = "best", cost = 34.43m });                      context.savechanges();                      console.writeline(count);                      console.read();         }     } }          public  class musicalbumcontext:dbcontext         {           public dbset<album> albums { get; set; }         }       public   class album        {         public string name { get; set; }         public decimal cost { get; set; } } 

}

you need following process

class program      {        static void main(string[] args)         {           using (var context = new musicalbumcontext())              {                   var count = context.albums.count();                   console.writeline(count);                   context.albums.add(new album() { name = "best", cost = 34.43m });                  context.savechanges();                  console.writeline(count);                  console.read();     } } 

}

  public  class musicalbumcontext:dbcontext     {       public musicalbumcontext()         : base("connectionstring")     {      }     static musicalbumcontext() {     database.setinitializer(new dropcreatedatabaseifmodelchanges<musicalbumcontext>()); }       public dbset<album> albums { get; set; }     }   public   class album    {     public string name { get; set; }     public decimal cost { get; set; } 

}

after run following commnads enable-migrations contextname add-migration initialcreate update-database -verbose -fource