I have a WPF Toolkit DataGrid,
First Item is selcted
User clicks on any other item on the Grid
I do some validations (any validation on selection change event of the WPF Toolkit DataGrid)
If validations returns false
I want prevent User from changing the previously selected Item
I tried saving previous index in a variable and set it again but it's not working
look at ICollectionView event Currentchanged, Currentchanging and the MoveCurrentTo methods.
this.MyGridItemsSource = new ObservableCollection<MyDataItems>();
this.view = (ICollectionView)CollectionViewSource.GetDefaultView(this.MyGridItemsSource)
this.view.CurrentChanging += your eventhandling goes here
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I am using Infragistics UltraComobEditor to show some values by filling it's ValueList property with items. The selected item is just like a template and it require to update all elements which are using that template.
To apply it again i need to fire it's SelectionChangeCommitted event, but it does not fire if item is already selected.
I am in the quest to find the drop down list element which was selected before the DropDownClosed event fire. Is there any way to get which element was selected or get the element under the mouse point after the DropDown event?
I have a kendo combobox
#(Html.Kendo().ComboBox()
.Name("ddSystems")
.Filter("contains")
.Placeholder("-- Select --")
.BindTo((IEnumerable<SelectListItem>)ViewBag.systemList)
)
Onchange, a textbox is loaded in ajax. A submit button posts the textbox value and combobox value to the controller. When I get back to the view, I need ddSystems to be reset to empty. I used
$('#ddSystems').data('kendoComboBox').value(null)
and
$('#ddSystems').data('kendoComboBox').text('')
but it always retains the previously selected value. Since I use ajax, this will not display the textbox and I am stuck. Please help.
This will clear the combo box and disable it
Google is your best friend....
var combobox = $("#comboBox").data("kendoComboBox");
combobox.value();
combobox.enable(false);
I just need to validate that at least one item in an autocompletebox has been selected (meaning the textbox is not blank) when a button is clicked.
My list etc is working fine ... Im just not sure how to do validation. In fact this is the first of any such silverlight validation I've done as the bulk of our work is readonly dashboard type screens.
In WPF I have a TreeView control where a particular item can be selected either by the user selecting the item directly in the tree view or by clicking on a screen control. The tree view is displaying a list of elements that are being displayed on a user defined form, basically a form designer application.
Here is my problem. When the user clicks on a screen control it calls a method that returns the TreeViewItem that represents the element. It then sets the IsSelected property to true for this element. It correctly changes the visual indicator in the TreeView and it raised the SelectedItemChanged event in the TreeView. This is all good.
However, it appears that somewhere behind the scenes the TreeView still thinks the previous item is selected. Here is why I have come to this conclusion. If I select ElementA by clicking on it in the TreeView is it correctly selected. If I then select ElementB by clicking on the screen control and programmatically setting the IsSelected property for the ElementB TreeViewItem it appears to have selected it correctly. Now if I select ElementA again by clicking on it in the TreeView it does nothing. The SelectedItemChanged event is not raised and the reverse selection box that indicates the selected item stays on ElementB. If I click on ElementB in the TreeView it also does not raise the SelectedItemChanged event, however it does not appear to update the internal flag since if I then click on ElementA on the TreeView it processes it correctly and raises the event.
The only workaround that I have found for this is in the SelectedItemChanged event handler to call the Focus method for the now selected TreeViewItem. If I do this I get the expected behaviour when I select screen controls and programmatically change the selected TreeViewItem.
This is not an acceptable solution though as it creates focus change flicker. When I select items on my form window the focus goes to the TreeView control and then back to the form, causing flicker and slight delay.
Anyone have any indeas.
Update
As requested here is some code. Here is my method of my Explorer window which is the manager of the TreeView in question.
public bool SelectItemByName(String controlName)
{
bool fReturn = false;
TreeViewItem tviToSelect = FindItemByName(_tviMaster, controlName);
if (tviToSelect != null && _tviSelectedItem != tviToSelect)
{
tviToSelect.IsSelected = true;
// Make sure the selected item is visible in the TreeView by expanding all of the parent nodes
ExpandAllParents(tviToSelect);
tviToSelect.BringIntoView();
fReturn = true;
}
return fReturn;
}
Every element has a unique identifier that I use as a cross reference between different areas of the interface. When you click a screen control it uses its identifier to find the cooresponding TreeViewItem in the TreeView. Then this code sets it as selected.
Then in my SelectedItemChanged event handler I had to include the following line.
_tviSelectedItem.Focus();
This fixes my initial issue but introducing the unwant screen flicker.
To recap, I select ElementA in the TreeView directly, then select one or more other elements in the form designer which in turn calls SelectItemByName to programatically set the selected item. All visual indicators show that this worked. In the TreeView the highlighted item changes to the new item that is selected. After selecting any number of elements through the form designer interface if you select ElementA by clicking on it directly in the TreeView it does nothing. It does not get highlighted and it does not fire the SelectedItemChanged event. If you inspect the SelectedItem and SelectedValue properties of the TreeView they all correctly coorespond to the item that was programmatically selected. However, the control somewhere appears to think that ElementA is still selected and doesn't recognize that the selection is changing.
I cannot believe that other people haven't run into this. It appears to be a significant flaw in the TreeView contol in WPF. Not sure if WinForms has the same issue or not.
Each TreeViewItem has an IsSelected property, and I suspect the old one isn't getting set to false. Try setting it to false whenever you set the new item to true.
var currentItem = treeView.ItemContainerGenerator
.ContainerFromItem(treeView.SelectedItem) as TreeViewItem;
currentItem.IsSelected = false;
If that doesn't work, try setting focus on the newly selected item at the same time as when you select it. Don't forget that WPF also has two focus scopes: Logical Focus and Keyboard Focus. You may need to set both.
treeViewItem.Focus(); // Sets Logical Focus
Keyboard.Focus(treeViewItem); // Sets Keyboard Focus
I have a WPF DataGrid. The DataGrid is bound to an IList. The list has many many items so the DataGrid MaxHeight is set to a predefined value and the DataGrid automatically displays a scroll bar. The selection mode and unit are set to "single full row".
The form has a button called "New" that adds an item to the list that the datagrid is bound to.After "New" is clicked, the new item should be the new selected item. I do this via : dataGrid.SelectedItem = newItem;
This works ..but not as well as I expect it to.
I also want the dataGrid to scroll down to the newly selected item .. Any idea on how to do this ?
Regards,
MadSEB
After you set the SelectedItem, make sure to call DataGrid.ScrollIntoView with the new item. This will make sure that the new item is visible on screen.