如何识别一对一关系中的依赖实体 Entity Framework Core？

Question

I have studied many articles about how to config one to one relationships. I have learned it.

But I couldn't understand how to find a dependent entity in one to one relationship?

For instance, we have two entities User and Developer . How to understand which of them is a dependent entity? Because I think we must add a foreign key to a dependent entity. So the first things to do, we need to find a dependent entity.

public class User
{
    public int Id {get;set;}
    public string PasswordHash { get; set; }
    public string FullName { get { return FirstName + " " +LastName;}}
    public GenderType Gender { get; set; }
    public bool IsActive { get; set; }
    public DateTimeOffset LastLoginDate { get; set; }
    public string FirstName { get ; set ; }
    public string LastName { get; set; }
}

public class Developer
{
    public int Id { get; set; }
    public byte Image { get; set; }
    public int Age { get; set; }
    public string Resume { get; set; }
}

Answer 1

A dependent is something that depends on something else. A baby is dependent on its mother for food etc. Identify which entity can stand alone, without the other.

For example, you may decide that a User might not be a Developer but a Developer is always a User - in this case your relationship is actually 1:0..1 (user:developer) and you're looking at Developer being a subclass of a User. If. You could alternatively arrange things in a has-a fashion, and Developer has a User property (but User doesn't have a Developer property because not every User is a developer)

You may decide that you can never have one without the other- in which case they would probably be a good candidate for being in the same table/same client side entity

To some extent the question can be academic; there may be situations where you want to treat one as dependent, and others where it's the inverse way round. It'll probably help you overall though if you make a decision about how your entities are related on the client side and this will drive how you map them on the database side