Entity Framework 5: How lazy loading works in different type of relations?

Question

I am using Entity Framework 5, MVC 4. My User has these relations:

User-Profile: 1 to 1 relationship. (one user has one profile)

User-Posts: 1 to many relationship. (one user has many post)

User-Roles: many to many relationship (one user has many roles, a role might be assign to many users)

My question is how Lazy Loading works according to each type of these relations, and how "deep"? When I get a User from Context, what will be loaded?

Any help would be appreciated!

Answer 1

The idea behind lazy loading is that the entity framework loads only the information that you have attempted to access. Consider the following:

using (MyContext context = new MyContext())
{
    User myUser = context.Users.First();
}

In this example, only the User object is loaded. None of the related entities are retrieved from the database until they are first accessed.

using (MyContext context = new MyContext())
{
    User myUser = context.Users.First();   // User is loaded from database

    Profile myProfile = myUser.Profile;    // Associated profile is loaded
}

In the second example, there are two database calls - one to load the User, and a second to load the Profile when it is first accessed.

All three types of relationships (one-to-one, one-to-many, many-to-many) have this same behavior: related objects are not loaded until first access.