Entity framework loads navigation properties without asking for them

Question

While working in a project I saw a strange behaviour I cannot understand with the loading of navigation properties.

Here is a small example that reproduces this "problem".

I want to load a Year, without including data of the company(navigation property).

My code:

public static Year GetYear(int id)
{
    using (var context = new testModelContainer())
    {
        var result = context.YearSet.FirstOrDefault(c => c.Id == id);
        //Company test = context.CompanySet.Where(c => c.Id == id).FirstOrDefault();

        return result;
    }
}  

This returns the year I want, without data in the navigation property, but if I uncomment the line and I just execute the line, maybe because I want to know the name of the company or whatever, it authomatically includes the company data into the Company navigation property of the Year.

Any idea how to prevent this behaviour? For security reasons I would want to avoid sendind data of the 'parents'.

I am using EF 6, .NET 4.5.

Answer 1

This is because you are executing your commands in one context. Entities share information about each other if working within one context.

Thus if you first retrieved the Year and then you retrieve the Company that has a reference to Year entity with the value of previously retrieved Year, your navigation property will be updated automatically and vice versa - Year will have Company property populated.

Answer 2

A context is a collection of all data that are fetched from the persistence unit.

So here what happens in your example:

---

Initially:

Context:
****************************
Empty.
****************************

---

After Fetch Year:

Context:
****************************
1) Year (Year.Company -> null)
****************************

---

After Fetch Company:

Context:
****************************
1) Year (Year.Company -> 2)  //Refers to second object in the context
2) Company
****************************

---

After Fetching another Company

 Context:
 ****************************
 1) Year (Year.Company -> 2)  //Refers to second object in the context
 2) Company
 3) Another Company
 ****************************

---

After Fetching the year that refers to "Another Company"

  Context:
  ****************************
  1) Year (Year.Company -> 2)  //Refers to second object in the context
  2) Company
  3) Another Company
  4) Another Year (Year.Company -> 3) //Refers to third object in the context
  ****************************

---

Answer 3

Probably you have lazy loading enabled.

Try to disable it:

context.Configuration.LazyLoadingEnabled = false;

Disable lazy loading by default in Entity Framework 4

Answer 4

Just use .AsNoTracking() on your first entity. Then it will not track entities and it wont load with your desired entity.