实体框架（CF）多个表PK到同一FK

Question

So I got a few tables like this:

    public class Family
{
    public Guid Id { get; set; }
    public virtual Career Career { get; set; }
}

public class Career
{
    public Guid Id { get; set; }
}

And a few more classes like that.

And then a table where all translations are for them depending on language.

public class Language
{
    public string LanguageCulture { get; set; }
    public Guid ObjectId { get; set; }
    public string Translation { get; set; }
}

My issue here is that I want Language to understand that ObjectId can come from any of these classes. How can I accomplish that? By default is creates a column for each table that refrences to it.

Answer 1

If you want to be able to use all the niceness of LINQ/Lambda (and for the sake of your relational model) I would suggest that you dont go down this path.

I would either create a separate link from Language to each class, or link directly to LanguageCulture and Translation from the classes that need it.

I would want to achieve a model which makes it as intuitive as possible to retrieve and work with the data, even though this may be a bit of a annoyance now when building it. I'm quite confident that you will be happy that you created real relationships a few months / years down the line.

If you were to continue with your example you would have something like:

var object = _dataset.Where( x=> x.somecolumn == somevalue);
var language = _dataset.Where( x => x.ObjectType == object.Type
                                    && x.ObjectID == object.ID );

Instead of simply doing

var object = _dataset.Where( x=> x.somecolumn == somevalue);
object.Language //if you create a separate link to each object
object.LanguageCulture // if you remove your Language object and link directly to what it is your after

In the latter you just need to get your original object and you could also make subqueries such as

var objects = _dataset.Where( x=> x.somecolumn == somevalue
                                 && x.Language.LanguageCulture.Country == "Sweden")

This query is still possible with joins in your original idea but in general will be more annoying to do.

If you want to avoid writing the same thing over and over you could use an abstract class with the language fields that you can inherit in all the classes that need it.