Removing objects from a bindinglist bound to a datagrid view

1
votes

I'm trying to remove objects from a BindingList that is bound to a DataGridView by doing this...

private void RemoveItems(List<Payment> removeList)
{
    for (int i = removeList.Count - 1; i >= 0; i--)
    {
    sortableBindingPaymentList.Remove(removeList[i]);
    }
}

Trying to debug this myself i attempted the following, however remover always = -1 (meaning that no match was found) and I'm 110% sure that my list of Payment's in removeList contains a match in my sortableBindingList...

private void RemoveItems(List<Payment> removeList)
{
    int remover;

    for (int i = removeList.Count - 1; i >= 0; i--)
    {
        remover = sortableBindingPaymentList.IndexOf(removerList[i]);
        sortableBindingPaymentList.RemoveAt(remover);
    }
}

Any help is appreciated and thanks in advance!

2
c#winforms
By any chance, the removeList parameter is brought from a DB or a Service? it might be that the sortableBindingPaymentList doesn't actually contain these instances, but other instances representing the same data. - Federico Berasategui
It is brought from a DB or service, so it seems like it was suggested below that I need to implement Equals from IEquatable to my Payment class? - Archaios7

2 Answers

1
votes

if removeList doesn't contain the same references (same objects) as the ones in sortableBindingPaymentList then the method will return -1, which i assume happens in your case.

It states here: that the "Remove" method of a list:

"This method determines equality using the default equality comparer EqualityComparer.Default for T, the type of values in the list."

Payment class should implement IEquatable interface.

Eg: 

     public class Payment : IEquatable 
     {
        public  bool Equals(Payment paymentObj)
             {
                 //is current instance equal to payment OBJ?
                 //if yes, then return true otherwise false
             }
      }

Now this call should work even if you have different instances of objects in list collections.

      sortableBindingPaymentList.Remove(removeList[i]);

Please post complete post if you need further help.

1
votes

I'm not sure I would go the IEquatable way.. depending on the ORM you're using that might bring you some trouble.

Do your entities have a primary key? you can try this instead:

private void RemoveItems(List<Payment> removeList)
{
    removeList.ForEach(x => sortableBindingPaymentList.RemoveAll(s => s.Id == x.Id));
}

P.S: I strongly suggest you to start using LinQ for these kind of operations instead of for loops.