Removing Items programmatically - using foreach

[Filippo P.]

Hi there,
I have a menu (Collection) that needs to be trimmed based on security access
of the
logged user.


protected void AdjustMenuBasedOnUserSecurity(Items ItemsList)
{
foreach (Item i in ItemsList)
{
if (i.Items.Count > 0)
AdjustMenuBasedOnUserSecurity(i.Items);

if (i.Tag == null)
continue;

if (this.LoggedUser.HasPermission(Convert.ToInt32(i.Tag)) == false)
ItemsList.RemoveAt(i.Index);
}
}


=======================
PROBLEM
Altought this proc is recursive, the FOREACH seems to not recalculate the
COUNT of the Items Collection at every run, so when I remove an item from
the list, I also pretty much screws the internal COUNT of the FOREACH.


=======================
SOLUTION
...hummm here is where you may put add some ideas... !!!


Thanks,
Filippo

 

[Nicholas Paldino [.NET/C# MVP]]

Filippo,

You really shouldn't use foreach if you need to modify the contents of
the list (change the state of the enumeration) during the enumeration.
Since you need to remove items, I would recommend using a for loop, counting
backwards from the last item (so that when you remove an item, you don't
have to worry about indexes shifting), like so:

protected void AdjustMenuBasedOnUserSecurity(Items ItemsList)
{
// The item.
Item item;

for (int index = ItemsList.Count - 1; index >= 0; index--)
{
// Get the item.
item = ItemsList[index];

if (i.Items.Count > 0)
AdjustMenuBasedOnUserSecurity(i.Items);

if (i.Tag == null)
continue;

if (this.LoggedUser.HasPermission(Convert.ToInt32(i.Tag)) == false)
ItemsList.RemoveAt(index);
}
}

This should work. This assumes that you implement IList, and have an
indexer.

Hope this helps.

 

[Peter Rilling]

First, I do not think that you can even add or remove collection items in a
foreach loop.

One idea might be to use a simple "for" loop that counts backwards. That
way, when you remove an item, your next position is not affected by the fact
that there is one fewer items.

 

[Filippo P.]

Is that the description of my ex wife???

jaja.