Entity Framework Model Restraints One-to-many relationships
Example
UserType belongs to many Users <-> Users have one UserType
One way navigation property with required
public class UserType
{
public int UserTypeId {get; set;}
}
public class User
{
public int UserId {get; set;}
public int UserTypeId {get; set;}
public virtual UserType UserType {get; set;}
}
Entity<User>().HasRequired(u => u.UserType).WithMany().HasForeignKey(u => u.UserTypeId);
One way navigation property with optional (foreign key must be Nullable type)
public class UserType
{
public int UserTypeId {get; set;}
}
public class User
{
public int UserId {get; set;}
public int? UserTypeId {get; set;}
public virtual UserType UserType {get; set;}
}
Entity<User>().HasOptional(u => u.UserType).WithMany().HasForeignKey(u => u.UserTypeId);
Two way navigation property with (required/optional change the foreign key property as needed)
public class UserType
{
public int UserTypeId {get; set;}
public virtual ICollection<User> Users {get; set;}
}
public class User
{
public int UserId {get; set;}
public int UserTypeId {get; set;}
public virtual UserType UserType {get; set;}
}
Required
Entity<User>().HasRequired(u => u.UserType).WithMany(ut => ut.Users).HasForeignKey(u => u.UserTypeId);
Optional
Entity<User>().HasOptional(u => u.UserType).WithMany(ut => ut.Users).HasForeignKey(u => u.UserTypeId);
