DataContext is missing properties in where statement - asp.net-mvc

Question

Could some tell me why I have no properties in my where statements after using a select statement for e.g.
db.Select(x => x.Lft).Where(x => x.DepartmentId == id);
// missing properties in the where clause
And could you help me correct my code to implement it please leave me an example of what to do to implement this thanks
Classes:
public class Department
{
public Department()
{
Products = new List<Product>();
}
public long DepartmentId { get; set; }
[Required(ErrorMessage="Please enter a name for the departments.")]
[DataType(DataType.Text)]
public string Name { get; set; }
[DataType(DataType.Text)]
[Required(ErrorMessage = "Please enter a valid url for the department.")]
public string Url { get; set; }
public int Lft { get; set; }
public int Rgt { get; set; }
public bool MenuItem { get; set; }
public virtual ICollection<Product> Products { get; set; }
}
my DataContext class
internal class DepartmentsTypeConfiguration : EntityTypeConfiguration<Department>
{
public DepartmentsTypeConfiguration()
{
Property(department => department.DepartmentId)
.HasColumnName("DepartmentId")
.HasDatabaseGeneratedOption(databaseGeneratedOption: DatabaseGeneratedOption.Identity);
Property(department => department.Name)
.HasColumnName("Name")
.IsRequired();
HasKey(key => key.DepartmentId)
.HasMany(x => x.Products)
.WithRequired(x => x.Department)
.WillCascadeOnDelete(true);
}
}
public class LeapFrogDataContext : DbContext
{
public DbSet<Department> Departments { get; set; }
public DbSet<Product> Products { get; set; }
public DbSet<ProductSpecification> ProductSpecifications {get; set;}
public DbSet<Specification> Specifications { get; set; }
/**/
static LeapFrogDataContext()
//: base("name=LeapFrogDataConnection")
{
//Database.SetInitializer(new LeapFrogInitializer());
//Database.SetInitializer(new DropCreateDatabaseIfModelChanges<LeapFrogDataContext>());
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Configurations.Add(new DepartmentsTypeConfiguration());
modelBuilder.Configurations.Add(new ProductsTypeConfiguration());
modelBuilder.Configurations.Add(new SpecificationsTypeConfiguration());
modelBuilder.Configurations.Add(new ProductSpecificationsTypeConfiguration());
base.OnModelCreating(modelBuilder);
}
}

Answer 1

db.Select(x => x.Lft) returns a list of int so in the where clause you will not access any property.
I guess you may switch select and where to achieve what you want. Assume db is the actual context.
db.Where(x => x.DepartmentId == id).Select(x => x.Lft)
That's a bit weird. Normally it should look like
db.context.Departments.Where(x => x.DepartmentId == id).Select(x => x.Lft)