Entity Framework add object to related entity without loading - entity-framework

Question

I would like to add an object to a related entity without loading them.
I have Company entity defined like this:
public class Company
{
public int ID { get; set; }
public List<Employee> EmployeeList{ get; set; }
}
And Employee entity like this
public class Employee
{
public int ID { get; set; }
public String Name{ get; set; }
}
I want to add an employee to a list placed in that company object without loading all the employees.
I know I can use this expression
Company myCompany= systemBD.Companies.Include("EmployeeList").Find(1) myCompany.EmployeeList.Add(newEmployee)
but I'm afraid that this would consume a lot of time since I have thousands of employees in my database.
Is there a way to add a new employee to an existing company without loading the list of Employees?
I was looking into the Attach method but it does not seem to work.
using (var systemDB = new CompanyDB())
{
Employee employee = new Employee ();
Company companySearch = systemDB.Companies.Where(d => d.Name.Equals("John")).SingleOrDefault();
if (companySearch != null)
{
if (companySearch.EmployeeList != null)
{
systemDB.Companies.Attach(companySearch );
companySearch.EmployeeList.Add(employee);
systemDB.SaveChanges();
}
}
I tried that code but it doesn't work.

Answer 1

Assuming you have your Company and Employee entities defined to have both a navigation property from a Company to the collection of all of its associated Employees and a property from an Employee to its single associated Company, you can accomplish creating a new Employee and associating it with an existing Company from the Employees DB set.
[Table("Company")]
public partial class Company
{
public Company()
{
this.Employees = new HashSet<Employee>();
}
public int Id { get; set; }
[Required]
[StringLength(50)]
public string Name { get; set; }
public virtual ICollection<Employee> Employees { get; set; }
}
[Table("Employee")]
public partial class Employee
{
public int Id { get; set; }
[Required]
[StringLength(50)]
public string Name { get; set; }
public int CompanyId { get; set; }
public virtual Company Company { get; set; }
}
public partial class Database : DbContext
{
public Database()
: base("name=Database")
{
}
public virtual DbSet<Company> Companies { get; set; }
public virtual DbSet<Employee> Employees { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Company>()
.Property(e => e.Name)
.IsUnicode(false);
modelBuilder.Entity<Company>()
.HasMany(e => e.Employees)
.WithRequired(e => e.Company)
.WillCascadeOnDelete(false);
modelBuilder.Entity<Employee>()
.Property(e => e.Name)
.IsUnicode(false);
}
}
Then assuming you already have a Company in the system with an Id of 1, you can do the following:
using (var database = new Database())
{
var company = database.Companies.Find(1);
if (company != null)
{
var employee = new Employee
{
Name = "John Doe",
Company = company
};
database.Employees.Add(employee);
database.SaveChanges();
}
}
OR...if you are sure that Company Id 1 definitely exists...
using (var database = new Database())
{
var employee = new Employee
{
Name = "John Doe",
CompanyId = 1
};
database.Employees.Add(employee);
database.SaveChanges();
}

Answer 2

I think you would need to change your Database Design to accomplish what you want.
Employee table
ID (Primary key)
Name
Company table
ID (Primary key)
Name
EmployeeCompany table
IDCompany (Foreign Key)
IDEmployee (ForeignKey)
This way you will accomplish what you want