One to Many And Many To One Insert in Ef 6.0 - entity-framework

Question

A doctor have one degree and one degree have many doctors,
well when i try to add new doctor ef 6.0 (DbContext) insert the selected degree as new record in Degress Table
i don know why ?
Insert Method :
public bool Insert<T>(T entity) where T : class
{
bool result = false;
try
{
Context.Set<T>().Add(entity);
result = Context.SaveChanges() > 0;
}
catch (Exception exp)
{
result = false;
fnLogExceptions(exp);
}
return result;
}
The insert Section :
private void btnSave_Click(object sender, EventArgs e)
{
var dr = new DB.Doctors();
...
dr.Degrees = dropDownList_Degree.SelectedItem as DB.Degrees;
...
using (var ctx = new Context())
{
opState = ctx.Insert<DB.Doctors>(dr);
}
...
}
the new doctor is inserted successfully but also it insert new copy of selected degree
thanks in advance

Answer 1

The Degree that you were trying to assign isn't from the database, its from the dropodown list. So the EF thinks its new, therefore inserting a new Degree.
You need to retrieve the existing degree from the database.
var dr = new DB.Doctors();
int selectedDegreeID = (int)dropDownList_Degree.SelectedItem.Value;
using (var ctx = new Context())
{
dr.Degree = ctx.Degrees.Find(selectedDegreeID); // Retrieval and assignment.
opState = ctx.Insert<DB.Doctors>(dr);
}