You can choose to don't save the collection ordered.

//class mapped by field, you can do it by properties as well, I prefer this
one.
public class Person
{
    private IList<Images> images;

    IEnumerable<Images> ImagesOrderedBySomeCriteria //just to iterate,
prevents to be modified in some ghost part of the application
    {
        get { return new ReadOnlyCollection(*OrderMyCollection*(this.images));
}
    }

    IEnumerable<Images> Images //just to iterate, prevents to be modified in
some ghost part of the application
    {
          get {return new ReadOnlyCollection(this.images);  }
    }
}

OrderMyCollection just order the collection into a new object that is
returned and passed as readonly (you can avoid the ReadOnly if you want).


On Fri, Jan 30, 2009 at 12:14 AM, reach4thelasers <
kev.m.mul...@googlemail.com> wrote:

>
> Hi guys,
>
> I have a small problem.  I've got a domain object Person,  a person
> has an IList of images which has an index to determine the position of
> each element in the list.  I want to take one element from the list
> and put it at the start of the list, list[0].
>
> I've tried the following:
>
> image oldfirst = Person.Images[0];
>
> person.Images[0] = Person.Images[4];
>
> person.Images[4] = oldfirst;
>
> personDao.Update(person);
> personDao.CommitChanges;
>
> also tried something similar with person.Images.Remove(image) and
> person.Images.insertat(0, images).
>
> But I'm getting a null reference expception because personID is null
> and index is null in my images table.
>
> So, can anyone tell me: what is the best way to take an object from an
> ordered list and put it at the beginning????
>
> Any help with this would be so greatly appreciated.  I am using 2.1.1
> though, so it could be a bug.
>
> Regards,
>
> Kevin.
> >
>
>


-- 
Dario Quintana
http://darioquintana.com.ar

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