I'm using MVVM pattern and C#, I public a ReadOnlyCollection property from View-Model,
In View, there is a TabControl that ItemsSource property is Binding to this ReadOnlyCollection Property.
How can I know which item is being selected from View-Model?
If ReadOnlyCollection cannot do this, what type should i use?
Thank you.
You can bind to the SelectedItem property of the TabControl to an additional property in your ViewModel.
Check MSDN for all the properties of TabControl.
Related
about to add the following features
If select this combobox, I want to change the itemssource of the datagrid.
Are there any examples related to this?
You can do the following:
Create a WPF project.
Create a view (xaml) with the combobox and datagrid inside it.
Create a view model for this newly created view and declare public properties (collection/list) for the ItemsSource of the combobox and the grid. Also have a property for the selected item of the combobox.
Set this view model as the data context of your view.
In the setter of the combobox's selected item - change the property which is bound to the datagrid's ItemsSource to the collection that you by calling a method or however you wish.
I did this:
Add the namespace for caliburn in xaml
xmlns:cal="http://www.caliburnproject.org"
Here is the combobox:
<ComboBox ItemsSource="{Binding ComboBoxItemSource}" SelectedItem="{Binding SelectedItem}" cal:Message.Attach="[Event SelectionChanged] = [ComboBoxSelectionChanged()]" />
and the viewmodel should be having this method:
public void ComboBoxSelectionChanged()
{
// here based on the SelectedItem you can change the ItemSource for the dataGrid.
}
Whenever you are changing the selectedItem of Combobox the method will get hit and based on the logic that you need you can assign the ItemSource for the dataGrid.
Hope this helps :)
I'm trying to bind combobox editor in a PropertyGrid to a list.
<dxprg:PropertyGridControl SelectedObject="{Binding SelectedEmployee}">
<dxprg:PropertyDefinition Path="EmployeeCountryID">
<dxprg:PropertyDefinition.EditSettings>
<dxe:ComboBoxEditSettings
ItemsSource="{Binding Path=DataContext.Countries, ElementName=rootWindow}"
ValueMember="CountryId" DisplayMember="CountryName" />
</dxprg:PropertyDefinition.EditSettings>
</dxprg:PropertyDefinition>
</dxprg:PropertyGridControl>
This example is from a third-party control but the problem may be just general.
The "rootWindow" DataContext has been set to a ViewModel which holds a property List(of Country) that I want have as ItemsSource in a Combobox.
I was trying to access that list by setting the Combobox ItemsSource to the rootWindow.DataContext.Countries property but I don't get any data.
Tried also all those RelativeSource FindAncestor bindings but no data appeared either.
Why can't I bind through a DataContext of a given element like this?
This became solved. The problem was not with the binding at all but realated to how I defined the third-party control: Instead of EditSettings I should have defined CellTemplate -> DataTemplate.
How can i use the SelectedItem in a treeview? I want to bind i to my Model. Why is this property in the treeview readonly? Is there a xaml Solution without Code-behind?
I have a UserControl with 4 combobox bound to collections in viewmodel for that usercontrol.
I have used this control in a wpf form. This wpf form has its own viewmodel.
How do i access the text from the 4 comboboxes within the wpf form's viewmodel?
EDIT: i saw that you have different viewmodels. now it depends of the use of your usercontrol and the use of mvvm:)
you can use messenger or eventaggregator to comunicate the seleteditems from usercontrolviewmodel to mainviewmodel.
you can also use RelativeSource binding in your usercontrol to bind the selecteditem to your mainviewmodel directly (usercontrol then is just a composition of controls).
you can can rid of the usercontrol viewmodel and put all in the mainviewmodel and take my old example
you can create DependencyProperties for the SelectedItems in your usercontrol!(not usercontrol viewmodel!) and bind these to the properties in your mainviewmodel. i think thats the cleanest way if the usercontrol should be a real usercontrol.
old example:
in your viewmodel: //the real code should of course implement INotifyPropertyChanged and raise it properly
public ObservableCollection<string> MyFirstCollection {get; set;}//init once, add,remove,clear to alter
public string MySelectedCombobox1Value {get;set;}
in your usercontrol:
<ComboBox ItemsSource="{MyFirstCollection }" SelectedItem="{Binding MySelectedCombobox1Value, Mode=TwoWay}" />
thats all relating to your question. be sure that you set the DataContext right. you can check this with tools like snoop. the code i posted expected that the dataconext for the combobox is the viewmodel.
The UserControl should inherit the data context of the form you're adding it to which would be the view model. Any bindings in the UserControl would then be relative to the inherited data context. Have you tried binding to a view model property to ComboBox.Text?
UPDATE
Sorry, misread your question. Didn't see that the user control already has its own view model.
While it seems like there's a better approach, you could expose dependency properties on the user control that exposé the text of each combobox. Just thinking out loud.
The only clean way to do this is with binding, and the only way that would be recommended is if the user control exposes a DependencyProperty for the ViewModel or the individual text properties (as was suggested by sellmeadog) for consumption. Then you can have a property in the parent ViewModel that binds directly to that Dependency Property.
I have ItemsControl with multi DataTemplate and use ItemTemplateSelector to chose appropriate DataTemplate of each item of ItemsSource. I want to binding ItemTemplateSelector to TemplateType dependency property of item. and each time TemplateType property changed, DataTemplate change automaticaly. How can I do.
I Search about own question. and find below code to refresh ItemTemplateSelector :
DataTemplateSelector DataTemplateSelector = plan.ItemTemplateSelector;
plan.ItemTemplateSelector = null;
plan.ItemTemplateSelector = DataTemplateSelector;
I'd go for a different solution in your case, if you want to update the datatemplate.
I would create a binding to the ItemTemplate of your ItemsControl. That binding gets a converter assigned, which contains the logic of your current ItemTemplateSelector. And the source of the binding is your TemplateType property.
The ItemTemplateSelector is just for one-shot evaluation.