CODEWITHSUNDEEP
c#
Rangel
Rangel

Reputation: 2683

How i do for work with objects with composition

my name is aderson and in this moment i have something question about composition referents to performance. In this model i have a simple userbase and departmentbase. The userbase have a property of type deparmentbase and departmentbase have a list property of type departmentbase. When i have a instance of userbase in this moment load information about department but then DepartmentBase load information about Departments too!!!.

Now, when i have a list of userbase for all user the process load again for all users, this is a good practise or what is the better form?

alt text http://img146.imageshack.us/img146/3949/diagram.jpg

Upvotes: 1

Views: 714

Answers (2)

Fredrik Mörk
Fredrik Mörk

Reputation: 158309

I don't know if it is a better (or even applicable) approach, but I sometimes make brief versions of objects that I use for references from other objects. The breif version acts as a base class for the full version of the object, and will typically contain the information that would be visible in a listing of such objects. It will often not contain lists of other objects, and any references to other classes will usually refer to the brief version of that class. This eliminates some unnecessary data loading, as well as some cases of circular references. Example:

public class DepartmentBrief
{
    public string Name { get; set; }
}
public class Department : DepartmentBrief
{
    public Department()
    {
        Departments = new List<DepartmentBrief>();
    }
    public IEnumerable<DepartmentBrief> Departments { get; private set; }
}
public class UserBase
{
    public DepartmentBrief Department { get; set; }   
}

One difference between this approach and having full object references paired with lazy loading is that you will need to explicitly load extra data when it is needed. If you have a UserBase instance, and you need the department list from the Department of that UserBase, you will need to write some code to fetch the Department object that the DepartmentBrief object in UserBase is identifying. This could be considered a downside, but I personally like the fact that it will be clear when looking at the code exactly when it is going to hit the data store.

Upvotes: 3

fretje
fretje

Reputation: 8372

It depends, if you need all the department data directly after loading the user list, then this is the best approach. If you don't need it immediately, you better use lazy loading for the department data. This means you postpone the loading of the department data until an explicit method (or property) has been called.

Upvotes: 2

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