如何强制查询检索嵌套元素数据？

Question

I'm making a JSON from my Database made with LINQ to SQL . I've set up Serialization Mode Unidirectional (so I can serialize data), and once I query my Object ( User ) I convert it to JSON :

[WebMethod]
public User GetUserByID(int ID)
{
    User user = db.User.Where(p => p.ID == ID).FirstOrDefault();
    var json = JsonConvert.SerializeObject(user, new IsoDateTimeConverter());
    return user;
}

The problem is that on the resulting JSON , the nested data/objects (ie the relationship I have for that Object to others Object/Tables) are null .

So, for example, if I have 3 Phone numbers (1-n relationship) for that user, instead of retrieve a JSON array with these (3) numbers, it puts:

"Phones": null,

how can I "force" the User to be queried with all data/relationship inside it?

And if I do this query (for example) before serialize:

var phones = m_oAlumno.Telefono.ToList();

it says "Self referencing loop detected for type 'User'."

Answer 1

In LINQ to SQL you can load referenced entities using DataLoadOptions.

var loadOptions = new DataLoadOptions();
loadOptions.LoadWith<User>(u => u.PhoneNumber);
db.LoadOptions = loadOptions;

Where PhoneNumber is an entity that references User and assuming db is your linq data context.