Datagrid Binding to ObservableCollection WPF

Question

I have Datagrid binding to a ObservableCollection as a source, data grid cells is allowed the user to change the values, the problem when I change the cells values the ObservableCollection do not update

Here's my Datagrid code :

<DataGrid.Columns>
    <DataGridTextColumn Header="Item" Binding="{Binding Item.ItemName,Mode=TwoWay}" Width="100" IsReadOnly="False" />
    <DataGridTextColumn Header="Price" Binding="{Binding SalePrice,Mode=TwoWay}" Width="100" IsReadOnly="False"  />
    <DataGridTextColumn Header="Qtn" Binding="{Binding Quantity,Mode=TwoWay}" Width="100" IsReadOnly="False"  />
    <DataGridTextColumn Header="Totla" Binding="{Binding Total,Mode=TwoWay}" Width="100" IsReadOnly="False"  />
</DataGrid.Columns>

any suggestions

*Unclear what you're asking.* What is your question? - Post the relevant data item class. — Federico Berasategui, Oct 07 '13 at 18:19
I don't think that will work, unless you hook up the CellUpdateChanged event to update that selecteditem. — 123 456 789 0, Oct 07 '13 at 18:19
@leolorenzoluis of course that is completely untrue and wrong. Two Way databinding is supported by default in WPF without any kind of code behind hacks. — Federico Berasategui, Oct 07 '13 at 18:22
That's not true, TwoWay binding is not set by default depending on the control. :P — 123 456 789 0, Oct 07 '13 at 18:32
@HighCore, it's not a binding thing per se. The WPF DataGrid uses a transaction scope to change editable rows. It means cancel/commit are baked in. Please read the duplicate... — Gayot Fow, Oct 07 '13 at 18:35

score 3 · Accepted Answer · edited May 23 '17 at 12:22

The WPF DataGrid uses a transaction scope when its cells are edited. What that means is that after changing a cell, a 'commit' is needed in order to persist the change. To force a commit, you can use the Tab key or the Enter key.

Lots of people will type a new value into a cell and then mouse into another cell or another control altogether. When this happens the DataGrid does a 'cancel' on the transaction and thus the change is not persisted in the underlying collection. In fact, almost anything other than Tab or Enter (or losing focus) will raise a cancel on the transaction.

If you want to capture changes regardless of what key the user pressed, then the underlying class should implement IEditableObject. This allows the view model to force a commit and persist the changed cell.

It's a known 'gotcha' on WPF DataGrids. There's a lucid discussion on it here http://blogs.msdn.com/b/vinsibal/archive/2009/04/07/5-random-gotchas-with-the-wpf-datagrid.aspx

Even more subtle 'gotchas' on the same subject are discussed here http://blogs.msdn.com/b/vinsibal/archive/2009/04/14/5-more-random-gotchas-with-the-wpf-datagrid.aspx

Possible duplicate of Why isn't a property in my ViewModel updated when DataGrid changes?

Garry, I want to ask you, let us say we have row with 4 cells. when I edit the first cell that make change to fourth cell. when I make Change in first cell and commit "Press Enter Key" in SelectionChanged event for datagrid I make the change on ObservableCollection, the fields changes in ObservableCollection but in datagrid "fourth cell" still keep old value Although the cell binding is two way. I hope this clear for you. — Abdulsalam Elsharif, Oct 08 '13 at 07:09
For that behaviour, you have to populate the 4th cell within the INPC handler — Gayot Fow, Oct 08 '13 at 08:34

score 0 · Answer 2 · answered Oct 07 '13 at 18:22

Implement RaisePropertyChanged to your properties(SalesPrice,Quantity,Total)'s Set method

ObservableCollection only notifies about collection changed events like adding,removing items from collection, The underlying class properties of ObservableCollection should implement the RaisePropertyChanged Events seperetly to detect changes in them

Datagrid Binding to ObservableCollection WPF

2 Answers2