DataForm + Combobox == Silly Bugs (combobox in dataFormToolkit:DataField)

UPDATE: So, this worked for SOME of the problems... not All.... Mosy on over to John's blog to see updates that he has for this issue. I believe he has fixed it.

Well... I haven't posted in a really long time... but this problem / workaround was worth it. My amazingly cool and awesome collegue John, had a most annoying problem. He was trying to bind a combobox to an itemsource then take the value of that itemsource and put it into a RIA Domain data source. Sounds easy right? well... not so when you're using the Silverlight 4 Toolkit DataForm / DataGrid.

Each time the form reloads (by adding, removing items from the collection) the bindings are reset, and not nicely... Long story short we found it impossible to get the combo box to work correctly using anything in XAML. For some reason "they" haven't made it easy in Silverlight.

To work around this issue the easiest thing I could come up with turns out to be pretty neat. On the Datafield that held the combo box, there is a Loaded event, so I thunk (yes, thunk; We were very frustrated...) why not just add a new combobox each time it loads so we KNOW that the bindings are correct.

Here is what we did:

Added an empty datafield to the grid in the dataform:

dataFormToolkit:DataField Grid.Row="5" Grid.Column="0" Loaded="ComboBoxField_Loaded" Label="Period Type" LabelPosition="Auto"

Note the lovely RED event handler.

in this hanlder we define the contents of this DataField:

Private Sub ComboBoxField_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)

Dim comboBoxField As DataField = sender 'Get the dataField that sent us here


Dim BindingForItems As New Binding With {.Source = ItemListDomainDataSource,
.Path = New PropertyPath("Data")}

'No need to set Source as it will pick up from the form

Dim BindingForValue As New Binding With {.Path = New PropertyPath("ItemValue"),
.Mode = BindingMode.TwoWay}

Dim combobox As ComboBox = New ComboBox 'Make a new combobox
combobox.DisplayMemberPath = "Name" 'Set Paths FIRST, yes, they have to be done first
combobox.SelectedValuePath = "PeriodType"
combobox.SetBinding(combobox.ItemsSourceProperty, BindingForItems)
combobox.SetBinding(combobox.SelectedValueProperty, BindingForValue)

'add styling wireups if not using default styling

comboBoxField.Content = combobox 'Push the new combobox back to the datafield

End Sub

So, load the data field, add the combobox, with its bindings already set. Now, for all those that are super concerned, like my friend John, about performance etc, you should go look at his blog, 'cause i am pretty sure he will take this and turn it into some shared resource.... :)

Isaac

Andrew Laughing

Working with the Portal Menu Structure via the database

I was trying to find all the object that were under a folder in the PIA portal via the data base. The problem is that the menu / component structure is not the PIA portal stucture and the object names in the portal are laid out differently. The portal stucture is laid out in the PSPRSMDEFN table. This table has a whole slew of infomation in it and is used to build the URLs for the portal to point to the menu / componet layer; the PORTAL_URI_SEG# fields are the different parts of the URL that the PIA layer uses to access the components.

Select * FROM SYSADM.PSPRSMDEFN where PORTAL_PRNTOBJNAME = ‘MY_PARENT_OBJECT’;

This gives all the objects directly below 'MY_PARENT_OBJECT'. The object type is stipulated by a C' for component or 'F' for folders; there are another couple of types for links etc... In order to find all the objects below another you would need a resursive function that drills down each level because for each object, you only have its parent.