Hello NHibernate-users

I would like to map to a SortedList in the .NET Framework Class Library, but I can’t find useful information concerning this matter.

A Group has multiple Categories. But the ordering of the Category-items within a Group is not based on a property of the Category business entity. No, a column in the Categories-table (Cat_PositionInGrp) maintains the key for ordering the Categories-items within a Group. As a result, I decided to use a SortedList(Of Integer, bsCategory). The user should be allowed to change this ordering at all time.

Herewith the code of both the Group- and Category business entity classes:




A brief overview of the necessary tables and its columns in SQL Server 2005:


I can not imagine that a .Net SortedList cannot be mapped through NHibernate. Or am I wrong?

I prepared a little example to give you an idea what I want to achieve:



When you iterate through the Groups and its Categories, the result should be (ordering the Groups is not necessary):

* GROUP 2
---> Category 208
---> Category 210
---> Category 205
---> Category 209
* GROUP 5
---> Category 204
---> Category 199

Anyone?

If your Categories property in the Group entity is mapped as a bag, then you can define the order-by column:

A simple but workable solution.

Thank you, Nels_P_Olsen.

I realize the original poster is satisfied with this answer, and I also realize that it probably works for what he or she is really trying to accomplish, but I do want to add some words of caution.

this really isn't doing the task which the original poster asked about. First, a SortedList is actually a combination of keys and values where all keys of the list are sorted and then the items are accessible via the key. This is very similar to a SortedDictionary.

Secondly, a bag technically has no order. It's not really a bag at all, it's just using a bag mapping to get through to the underlying implementation.

Third as soon as you add an item after the collection is loaded from the database your ordering is now lost. If the poster was actually using a SortedList the items would automatically be sorted correctly for every item which is added.

Personally when I develop applications I never rely on the order-by clause. Instead I would only use it as a performance improvement if it is advantageous to have a sorted collection before I manually sort it. Some algorithms are faster sorting an already sorted list.

The fact remains that I do not know the current state of an object (from my domain objects at least) regarding what came from a database and what has been modified since. For some of our operations many things could have taken place. Making assumptions like this that any given IList would be sorted would not suffice for us.

Caution should be taken in making assumptions regarding the ordering of the original posters list.

Thank you for your contribution, jchapman.

One of your sentences was a tricky thing I overlooked: "If the poster was actually using a SortedList the items would automatically be sorted correctly for every item which is added."

The best solution is to get the SortedList-thing working.

I do not know how, but in the coming days I will try to work something out to achieve exactly what I was trying to achieve.

fyi: I am a He, bennieke is just a Dutch diminutive of my real name Benny