当我在EF5中包含父级数据时，是否有办法避免获取子级数据的另一个副本？

Question

I have the following classes and I am having a problem with getting data from them:

public partial class Exam    {
    public Exam()
    {
        this.Objectives = new List<Objective>();
    }
    public int ExamId { get; set; }
    public int SubjectId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public virtual ICollection<Objective> Objectives { get; set; }
}

public partial class Objective    {
    public int ObjectiveId { get; set; }
    public int ExamId { get; set; }
    public string Name { get; set; }
    public string Text { get; set; }
    public virtual Exam Exam { get; set; }
}

I am getting a list of Objectives and I want to include Exam.Name.

Here is the query that I created so I could get Exam which would give me a way to get the Exam name.

    public IList<Objective> GetObjectives(int examId)
    {
        var objectives = _objectivesRepository
            .GetAll()
            .Include(o => o.Exam)
            .ToList();
        return objectives;
    }

Here is the mapping that I am using:

    public ObjectiveMap()
    {
        this.HasRequired(t => t.Exam)
            .WithMany(t => t.Objectives)
            .HasForeignKey(d => d.ExamId)
            .WillCascadeOnDelete(false);
    }

Unfortunately this small query returns over 6MB of data. When I check with Fiddler I see:

Objective objects > Exam objects > Objective objects

What I need to have is:

Objective objects > Exam objects

Is there a solution for this. How can I stop EF5 from getting another layer of objectives?

Answer 1

JSOn serialization is a different issue. Not related to entity framework here. You can use ScriptIgnore attribute to avoid serializing it,

public partial class Exam    {
 //....
    [ScriptIgnore]
    public virtual ICollection<Objective> Objectives { get; set; }
}