Remove an item from Observable collection

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I have a Radgridview and i am deleting items from it using a checkbox.But when i delete it is always deleting the first value not which i have selected.

C#

var takeoffsSelected = TakeOffInfoCollection.ToList().Where(x => x.IsSelected);
            //Deleted Takeoff
            foreach (var takeoff in takeoffsSelected)
            {
                objTakeOffModel.DeleteRecordFromDB(SageVariables.Project_ID, SageVariables.CurrentQuoteID, takeoff.DeleteID);
                TakeOffInfoCollection.Remove(takeoff);
            }

Posted 9-Feb-15 1:59am

chandra sekhar

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Rob Philpott 9-Feb-15 8:08am

What type is takeoff? That's the problem with var, it leaves us with no idea.

I suspect you probably have an equality issue on the type, whereby you are expecting it to perform comparisons by the objects reference, but its using the Equals() method on the type. Check your identity logic.

chandra sekhar 9-Feb-15 8:13am

takeoff is TakeOffInfoDomain

Kornfeld Eliyahu Peter 9-Feb-15 9:08am

Change var to the actual type...

chandra sekhar 9-Feb-15 9:10am

Changed but still no use.

Kornfeld Eliyahu Peter 9-Feb-15 9:55am

When you use LINQ on observable collection the result no more observable...So probably the types are not fit anymore...
Have you checked the runtime-type of your vars?

johannesnestler 9-Feb-15 10:33am

??? runtime type? var is compile time type identification, no?

Kornfeld Eliyahu Peter 9-Feb-15 10:34am

var is a type to tell 'I do not care'...

johannesnestler 9-Feb-15 10:38am

no, not in C# (this is not VB) - there is no runtime type identification involved, just syntactic sugar. the type is always known at compile time...

Kornfeld Eliyahu Peter 9-Feb-15 12:32pm

'I do not care' means that OP - in this peace of code - do lazy work...There is no reason to use var, but set the type may show the problem...

johannesnestler 9-Feb-15 10:41am

In OP's case I suspect he is confused about the type, I think you are on the right track that: TakeOffInfoCollection.Remove(takeoff); maybe won't work....

johannesnestler 9-Feb-15 10:31am

yes not very readable, but changing to the actual type won't change anything here... The compiled result is exactly the same...

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johannesnestler · Answer 1 · 2015-02-09T04:30:00

Hi
First: Your code does unneeded conversion to a list while you just need enumeration (and in the wrong order too).

So if you need your result enumerated (and you enumerate it again after that...)
you would write:

C#

var takeoffsSelected = TakeOffInfoCollection.Where(x => x.IsSelected).ToList();

So you transform the result to a list after searching the matching elements.

What you do now is:

First enumerate all elements to a new list, then in Memory (not via the original query provider) you use LinqToObjects to search the list. then you enumerate the results. - You see this is "not so good"...

Just write:

C#

var takeoffsSelected = TakeOffInfoCollection.Where(x => x.IsSelected);
foreach (var takeoff in takeoffsSelected)
                ...

So your current code is not very efficient (depends on the cost of transforming all items to a in-Memory list...) but should work. So the Problem is not in the code you are showing. -Maybe the checkboxes don't set the IsSelected propery correctly or something like that, debug and see....

Kind regards Johanne