Question

I seem to be needing to “re-order” my result set after i make some modifications to it, is this “a feature” if so, some enlightenment? am I missing something?

//need the "IN" type functionality to limit my initial set.
 var resultSet = from t in someContext.SomeEntities
                       .Where("it.some_id IN{" + string.Join(",", array) + "}")
                              where t.obj_id == objtId
                              orderby t.tInt
                              select new customObj
                              {
                                  prop1= t.t1,
                                  prop2 = t.tInt,
                                  prop3 = t.tInt2 
                              };

//Do some other lookups / decision branching and 
//determine that i need to remove the following:

//just for arguments sake
resultSet.ToList().RemoveAll(o => o.prop1== 8 
                    && o.prop1 == 5 
                    && o.prop1 == 11 
                    && o.prop1 == 21); 


foreach (var vals in resultSet)
{
//do something that depends on the order
}

after that sequence.. something that i expected to be in order, is not.. when i do another orderby on the result set like:

foreach (var vals in resultSet.OrderBy(o => o.tInt))
{
   //now the order's okay
}

then it’s what i would’ve originally expected..

so should i not do any ordering until i have filtered my result set down? In this case obviously i could’ve done some filtering on the initial query, but in my situation, i really cant..

..thanks in advance.

UPDATE:

I must be doing a .ToList() on it for the (.RemoveAll()), is that the culprit then?

http://msdn.microsoft.com/en-us/library/wdka673a%28v=vs.90%29.aspx

Answer 1

IMO I think you should remove the initial orderby t.tInt and do an order by once you have filtered the list with your line:

resultSet.ToList().RemoveAll(o => o.prop1== 8 
                    && o.prop1 == 5 
                    && o.prop1 == 11 
                    && o.prop1 == 21);

I have never heard of RemoveAll() changing the order but it is very possible. Either way it will be more efficient to sort fewer records in the long run. I almost always do my sorting after I have filtered things.

Hope this helps.