I searched this site and i found 2 Links
how to load wpf usercontrol in MVVM pattern
MVVM-Light: Load UserControl into Window
but still i cant find the answer to my problem and this link
MVVM-Light Locator Pattern and Reusable UserControl
i Didn't Understood.... so here is i am stating my problem which might help others struggling like me ......
I have a MainWindow which has 2 parts one has a TreeView(a
UserControl) and the other Displays different user controls(named DisplayPanel).... just like windows Explorer.
The Display Panel on the Right side will display different user controls on Clicking nodes of tree view.
and my TreeView is Itself a user Control.
How can i make this composite UI Work using MVVM. Also I am planning to use MVVM light Toolkit. Does this have something that can help...
An Example will be great
Thanks... :)
Edit
My TreeView in a UserControl I made a dependency property in the UserControl which catches the selected Item fo the tree view so that i can use this dependency property to populate the required view in the "MainView" ContentControl binding....as you advised me in the comments. Everything is till now
Problem is that i want to display data contained in the the selected item and i cannot set the DataContext of the UserControls(which will be displayed in right hand side) to the selected item as then i will not be able to use my view model for the respective usercontrol for commands and other operations
I tried to solve this too.... i used the Mediator (Messenger) in my TreeViewUserControl view model to send a Message to the Usercontrol's(the one that i need to display) view model . Message will be passed whenever the item is selected in the tree view. and message contains the selected node. I forgot to mention i set the datacontext of the UserControl to its view model so that i could display data
But using this approach the problem is that when the I click a type of node for the first time the data is not populated but if the same type of node is clicked again its populated. What’s happening is that UserControls object is availabe when the the tree item is clicked for the first time and Mediator sends the message. So Mediator is not able to pass the message to the userControl view model.....
I totally do not have ne idea to solve this further.... is my way if displaying user control right or I should do something that else....totally confused.....
You could try defining a DataTemplate for each type in the TreeView's ItemsSource and instead of having a specific UserControl on the right side, just bind to the TreeView's SelectedItem. Alternatively, you could use a DataTemplateSelector.
Edited for OP's Edit
Did you do this?
MainWindow has TreeView whose ItemsSource=Binding MainVM.Items.
MainWindow has ContentControl whose Content=Binding TreeView.SelectedItem.
Somewhere in project, have ResourceDictionary where each possible type in MainVM.Items has a DataTemplate defined?
Which ViewModel (MainVM or ItemVM) are you trying to use and why can't you use it?
Related
I need to build a custom items control in WPF, where the user can drag/drop the items. Normally I would just maintain a list of view models and use a data template to define how the items should be displayed (in this case, a button). But I am concerned that this will make the drag/drop difficult as the ItemsSource objects will be view model objects , not the actual button.
My other potential approach is when an object is added to the ItemsSource, create a button in c# and add it manually, that way I can access the button directly to do drag/drop.
What would your advice be?
I have solved my issue. I found a way to get the control being render from the data template
I'm developing a WPF C# app where I have a tree view control and if the user clicks on a node in the tree, a node-specific detail 'form' appears in a named Grid somewhere else in the form. If you click on a different node in the tree, the displayed detail form checks if the contents are saved, is dismissed, and a new detail form appears in it's place.
What I need is some starting advice. Can I still implement the forms as standalone xaml, then put some some of 'container' in the grid that I throw the form into as a child? Or just add the form as a grid child somehow. How do I programmatically load the form I want in the grid and communicate with it?
Thanks for any assistance!
Corey.
Use an event aggregator design pattern, see here for details:
http://martinfowler.com/eaaDev/EventAggregator.html
You can then have some other code which listens for the node change clicks via the event aggregator and response accordingly. This will decouple your code and make it more testable.
Am assuming you are using mvvm?
If not read up on it - will make it easier.
then you have your form with the treeview on it, bound to its itemsource on the view model.
Usually an items control like a treeview will have a selecteditem property on it.
Bind that to a property on your viewmodel which is of the type of objects contained in your treeview. Call this for example CurrentlySelectedItem.
Your details 'form' can be a control or whatever you want on the same form.
Now depending on how complete your object is - you have at least two options. If your object in the treeview has all the data you need already, then just bind the details to CurrentlySelectedItem.
Obviously it must implement INotifyPropertyChanged to tell the binding system to update the values.
If the object doesn't have enough info, then on the setter of CurrentlySelectedItem you can then fire a method to load the full object and then bind the details to that full object.
Alternativley, another popular approach, you could have the details form as a self contained control that subscribes to a message and when it recieves the message with the key of the treeview object, it loads the required info.
I have several controls in my WPF window. I have divided the window into 4 sections. If I click on the section in the upper left, I want to copy the contents of this section in another window popup.
What I want to copy is a grid that can contain a lot of different controls, ex: togglebutton, button, panel... derived from ItemsControl, Control... and with DependencyProperty, ObservableCollection etc..
I tried :
XamlWriter.Save(data);
XamlServices.Save(data);
but I always have these errors :
Cannot serialize a generic type 'System.Collections.ObjectModel.ObservableCollection`1 or
A BadImageFormatException has been thrown while parsing the signature. This is likely due to lack of a generic context. Ensure
genericTypeArguments and genericMethodArguments are provided and
contain enough context.
You should not clone XAML itself, this is brutal and wrong way.
Take a look at the possible MVVM solution below. Let's say single DataGird represents a single business Item, so you need following:
ItemsWindow.xaml - represents a ListView and single item of ListView is DataGrid representing an item details
ItemsViewModel - expose list of Item objects (ObservableCollection<Item> Items { get; set; })
Each item of the ItemsWindow.ListView is represented by a DataTemplate like ItemDataTemplate
ItemsViewModel exposed command ICommand CopyItem and in command handler actually copyiing only instance of the Item business entity and adding it to the Items list, WPF reflects this changes via bindings and UI will be updated by a new ListViewItem with a DataGrid representing a details of just copied Item
Useful links:
Model View ViewModel pattern
Commands
Data Templating Overview - short and clean overview of WPF data templates with examples
I have a user control on a page and I'd like to load another custom user control within it's grid. However I want the user control type to be dynamic - e.g selecting "Calculator" from a drop down list would display my custom calculator control and selecting "Currency Converter" would load my currency converter. Can anybody help?
By the way I am trying to stick to MVVM.
Thanks in advance.
One way is to define multiple DataTemplates one for each child. As user selects the option set the corresponding ViewModel to a ContentControl's DataContext present in parent view and framework will pick the corresponding view for you.
John Papa has written a great blog post on exactly how to do this here.
The basic strategy is to instantiate a new instance of a class that derives from UserControl once selected from the drop down.
In other words, the SelectionChanged event of the drop down list could be handled and a new UserControl object created based on the selected item.
I'm sure there is a simple answer to this but I can't seem to find it. Most examples for binding TreeView nodes are about using a ListView to show the node's details. In the scenario I am working on I've got a TreeView data bound to an Xml document using a simple MVVM pattern. As each node is selected in the TreeView I want to show a different UserControl for the type of XmlNode being represented.
What is the best control for hosting the different View's? (ViewBox, Panel?)
What's the best way to bind the view to the Selection in the treeview?
Thanks
In an application I'm working on I have a similar scenario. You should use UserControl to host your views.
In the TreeView each item controls its own IsSelected state. Have you tried binding to the TreeView's SelectedItem property? What I actually did was create an attached property for the mouse double click, and bound it to a Command. I defined this binding in my HierarchicalDataTemplate.