How should I disable Entity Framework table reference(foreign) list from each objects?

Question

I'm using Sqlite database and System.Data.SQLite 1.0.92 There is 2 table here:

---

Table Person:

PersonId

PersonName

---

Table Student:

StudentId

PersonId(reference table Person FK)

StudentNo

---

Now every time I get the Persons Collection in EF5:

using (var ctx = new myEntities)
{
  AllPersons = ctx.Persons.ToList();
}

There is also has AllPersons.student collection will include in the result;

But I don't need it. Of course that's just an example, There is a lot of big table has so many references, it always has performance problems here because of that.

So I'm trying to do not let it in my result. So I change it:

using (var ctx = new myEntities)
{
      ctx.Configuration.ProxyCreationEnabled = false;
      ctx.Configuration.LazyLoadingEnabled = false;
      AllPersons= ctx.Persons.ToList();
}

Now fine, because AllPersons.student collection will always be null

But now I found: If I get Person and Student together:

using (var ctx = new myEntities)
{
    ctx.Configuration.ProxyCreationEnabled = false;
    ctx.Configuration.LazyLoadingEnabled = false;
    AllPersons= ctx.Persons.ToList();
    AllStudents = ctx.Student.ToList();
}

Now the reference still include in.

So Is there anyway to don't let the reference include in any time in this situation? Thank you.

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Update

For some friends request, I explain why I need it:

1: When I convert it to json it will be a dead loop. even I already use Json.net ReferenceLoopHandling, the json size very big to crash the server.(if no references, it's just a very small json)

2:Every time I get the client data and need to save, it will display exception about model state, until I set it to null.

Example:

using (myEntities ctx = new myEntities())
 {
 ctx.Configuration.LazyLoadingEnabled = false;
 ctx.Configuration.ProxyCreationEnabled = false;



  Person model= ThisIsAModel();

  model.students = null;  // This is a key, I need set the students collection references to null , otherwise it will throw exception

  ctx.Entry(model).State = EntityState.Modified;
  ctx.SaveChanges();

}

3: This is More important problem. I already get all data and cache on the server. But It will let the loading time very long when server start. (because the data and references are so many, that is the main problem), I don't know I'll meet what kind of problem again....

public List<Person> PersonsCache; // global cache
public List<Student> StudentsCache; // global cache
using (myEntities ctx = new myEntities())
 {
     ctx.Configuration.LazyLoadingEnabled = false;
     ctx.Configuration.ProxyCreationEnabled = false;
 // There is so many references and data, will let it very slow , when I first time get the all cache. even I only get the Person model, not other , just because some Collection has some references problem. It will very slow....

   PersonsCache = ctx.Persons.ToList();
   StudentsCache= ctx.Student.ToList();
}

Answer 1

The Problem

As you said, when you load both of Parent and Child lists even when LazyLoading is disabled, and then look in parent.Childs you see child items has been loaded too.

var db = new YourDbContext();
db.Configuration.LazyLoadingEnabled = false;
var parentList= db.YourParentSet.ToList();
var childList= db.YourChildSet.ToList();

---

What happened? Why childs are included in a parent?

The childs under a parent entity, are those you loaded using db.YourChildSet.ToList(); Exactly themselves; In fact Entity Framework never loads childs for a parent again but because of relation between parent and child in edmx, they are listed there.

---

Is that affect Perforemance?

According to the fact that childs only load once, It has no impact on perforemance because of loading data.

---

But for serialization or something else's sake, How can I get rid of it?

you can use these solutions:

Solution 1:

Use 2 different instance of YourDbContext:

var db1 = new YourDbContext();
db1.Configuration.LazyLoadingEnabled = false;
var parentList= db.YourParentSet.ToList();

var db2 = new YourDbContext();
db2.Configuration.LazyLoadingEnabled = false;
var childList= db.YourChildSet.ToList();

• Now when you look in parent.Childs there is no Child in it.

Solution 2:

use Projection and shape your output to your will and use them.

var db1 = new YourDbContext();
db1.Configuration.LazyLoadingEnabled = false;
var parentList= db.YourParentSet
                  .Select(x=>new /*Model()*/{
                      Property1=x.Property1,
                      Property2=x.Property2, ...
                  }).ToList();

• This way when serialization there is nothing annoying there.
• Using a custom Model class is optional and in some cases is recommended.

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Additional Resources

As a developer who use Entity Framework reading these resources is strongly recommended:

• Performance Considerations for Entity Framework 4, 5, and 6
• Connection Management