Entity Framework
Modellfesseln

Eins-zu-Viele-Beziehungen

UserType gehört zu vielen Benutzern <-> Benutzer haben einen UserType

Einwegnavigationseigenschaft mit erforderlich

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);

Nullable mit optionalem (Fremdschlüssel muss Nullable Typ " Nullable " sein)

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);

Zweiwege-Navigationseigenschaft mit (Erforderliche / optionale Änderung der Fremdschlüsseleigenschaft nach Bedarf)

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;}
}

Erforderlich

Entity<User>().HasRequired(u => u.UserType).WithMany(ut => ut.Users).HasForeignKey(u => u.UserTypeId);

Wahlweise

Entity<User>().HasOptional(u => u.UserType).WithMany(ut => ut.Users).HasForeignKey(u => u.UserTypeId);