I am trying to clone a WPF bound object (a listbox) with code like the following
pgeIncidentReport newPage = new pgeIncidentReport();
newPage.SetReportData();
string listXaml = XamlWriter.Save(newPage.lstUsers);
However, when you view the listXaml string, I noticed that my databinding directives, for both the list itself and the DataTemplate are blank and no longer there. Is there a reason why that is being removed? Is there another way to clone objects that will maintain all of the settings?
Hate to answer my own question, but I found the answer by using this class: http://www.codeproject.com/KB/WPF/XamlSerializer.aspx
This article also helped to a certain degree but the solution in the first article is much easier to implement: http://www.codeproject.com/KB/WPF/xamlwriterandbinding.aspx?fid=1428301&df=90&mpp=25&noise=3&sort=Position&view=Quick&select=2801571
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I am looking to bind a richtextbox's text property to an array or list of custom objects. Is this possible? I see lots of WPF related binding for richtextbox but I am doing this in winforms. My searches for an example article have not turned up anything of value yet. Figured I would ask here.
One of my database calls returns to me a list of specific instructions and I would like to stuff this entire list of instructions into the richtextbox all at once. The text property does not support an IEnumerable type so I am not sure if I can do what I am trying to do or not. I was looking for a method to fill my richtextbox without all the for looping and inserting one item at a time. I figured data binding was the best fit for that.
I've run across the same problem and have solved it by creating a custom ValueConverter. The code for it can be found here.
Basically it takes an IEnumerable in and then returns a string with a custom separator (defaults to NewLine).
Could anyone answer a really frustrating newbie question please?! I've been hunting for an answer for a few days & have found answers to similar questions posed, but nothing that exactly solves my issue.
I'm trying to bind a textbox to the currently selected item in a listview (which itself is bound to an Observablecollection of objects, not sure if this matters).
The listview is in RecentEntities.xaml & the textbox is in Relationship.xaml, both of which are positioned on the Main Window from within Maincontrol.xaml. So they're in the same namespace but they're in different pages so using ElementName doesn't work as this just seems to look within the current page.
The issue I'm having is when trying to define the source of the textbox binding in Relationship.xaml, how do I reference the selected listview item in RecentEntities.xaml? I wondered about using RelativeSource, but this seems to only let you navigate up the tree to an ancestor of the current control. Because of how MainControl is set up, I would need to travel up to the parent of the textbox, then to a sibling of the parent then down to a child of a child of it in order to get to the listview!
I've explored (possibly not in enough depth) other options like resources, data context, including header files and have read something about Merged Resource Dictionaries but to be honest the more possibilities I explore, the more confused I'm getting about what I need to be doing.
Is this really as complicated as it seems?! Any pointers or help would be brilliant, thanks for taking the time to answer :) I haven't posted on here before, so if you need any code snippets please let me know.
Can you create a ViewModel that both Views will use? Have the selected item in your listview bind to a property in the ViewModel and have the textbox bind to the same property. As long as both views reference the same instance of the viewmodel, it should work.
With two XAML files you will have to use the model or viewmodel (depending on your choice of architecture) for synchronization.
For the listview you can use the SelectedValue to bind to a property, use Mode=OneWayToSource for this binding since you just want to update the property, not change the selection in the listview itself.
This will probably be obvious but I can't find the best way.
I want to show the user's ToDo's in a listbox. These ToDo's are in the database and consist of an Id, UserId and Description.
The user logged in to the app.
How can I retrieve the ToDo's for that certain userId and set it up for binding to the listbox?
I was trying with an ObjectDataProvider but I cant figure out how to use that in combination with nonstatic stuff (like my _dbService, userId, language, ...).
Are the only options to make all those things static versus binding in the code behind?
If so, this means that ObjectDataProvider isn't very useful, no?
I find a lot of examples of it being used with a hardcoded parameter but I hardly see any situation where I'd need such a functionality..
I do all my WPF using the Model-View-ViewModel pattern. I've given you one link there but Google will give you loads. MVVM seems to be the standard pattern for WPF. This project is probably more complicated than you need but it is well-written and brings home the use of MVVM.
Basically, you create a Model of your data. In this case, you'd probably create a simple class (I'll call it ToDoItem) with properties Id, UserID and Description. Use your preferred mechanism to get a collection of these from the database. Link to SQL, Entity Framework, a standard query, whatever.
Then you have your ViewModel - you have an instance of the ViewModel for each instance of the Model: the VM has a reference to the M and 'forwards' properties to it. The ViewModel is what you use to manipulate the model.
Then you have your View - this is the UI. You set the DataContext of the View to be the ViewModel and then your bindings automatically bind to the ViewModel. Your View just ends up being the things you can see. All of the work gets done in the ViewModel. This means it's very easy to test.
So, when you click on a button in your View, the bindings pass this onto a Command in your ViewModel which manipulates the Model.
The UI is also a View with a ViewModel. So, your UI VM might load a collection of Models from the database and stick them in an ObservableCollection. The ListBox items collection would be bound to this ObservableCollection.
It's hard to explain all of this in a post like this. Read a couple of articles and see what you think. I'm still quite new at this, too, but I believe my reading about MVVM has paid off.
Hela Thomas, Tom here from Orbit One :)
MVVM is the way to go. I'm on my 4th project and WPF really shines if you use mvvm. You already tried MVC (or MVP as we did on recy*tyre) and that's a nice separation of concern.
MVVM takes it a step further since the viewmodel knows absolutely nothing about the view.
The view binds to the viewmodel, so it has a reference to it (2 way, super powerful and works beyond the typical MS demo). The viewmodel is just a poco and is a representation of your view, data + behaviour. Once you dig this paragraph the cool term mvvm will have no secrets.
I see if I can come up with a small demo. Maybe I'll have time later.
What I will come up with is a view (xaml, file 1) that binds to a viewmodel (file 2, a poco class, not to be mistaken with code behind). The model can be whatever you like (service layer or directly to the repositories). Using the power of 2 way binding we will bind to an observable collection meaning that if we add/delete/... something to the collection the view will pick it up without us putting energy into it.
My first 2 wpf projects was done with Caliburn Micro (see codeplex) which is a powerful framework based on conventions. It shields you away from hardcore wpf (creating tour dependency properties yourself mainly) and you can create something relatively fast without fully understanding wpf. That's a downside of itself but it worked for me. As of project 3 I started taming those dependency properties myself and it will make you a better wpf developer.
I see the question is from October.. did you find a good solution?
I hope that someone can help me with an issue related to binding a bindable collection class to one of the Winforms Telerik list controls.
If you bind to a plain ole windows list control like this...
dim list as new listBox
with list
.DataSource=myCollectionClass 'this contains a collection of widgets.
.ValueMember="WidgetID"
.DisplayMember="WidgetName"
end with
I can then get a widget out of the list by doing this...
Dim myWidget as Widget=ctype(list.Items(0),Widget)
If you do the exact same code with for example a Telerik RadListBox (same example as above)
but change line one to be
Dim list as new RadListBox.
With RadControls it seems you cannot cast to the Object type directly. Whenever I try this I get the following error...
Unable to cast object of type 'Telerik.WinControls.UI.RadListBoxItem'
to type 'Widget'.
Can someone at the least confirm that this is a known limitation of Telerik RadControls for Winforms or let me know the proper way to do it.
Thanks. Any help will be appreciated. Any thoughts?
Seth
I also asked this question on the Telerik forum. Here is the answer I got...
"You can take the data bound item by the DataItem property that RadComboBoxItem exposes. For example:"
Me.Text = (CType((CType(Me.RadComboBox1.SelectedItem, RadComboBoxItem)).DataItem, Employee)).Phone
Seth
I have a List<Foo> from a non-WPF assembly which I'm attempting to databind to a WPF <ListBox>. Initially, the list items display correctly, but when I add a new item to the List<Foo>, the listbox doesn't add a list item. How do I tell the list box to re-bind / update / refresh the data and show the new item?
Although using an ObservableCollection is the best way, to answer the actual question, the way to update manually is to call BindingExpression.UpdateTarget
You should use a ObservableCollection instead, then you'll get updates automatically.
Thanks for posting this answer. Even if you use ObservableCollection, you may need to use BindingExpression.UpdateTarget. This can be the case if the collection is not in the UI thread. I've been writing some multi-threaded WPF apps, and I've been finding myself having to strip out data binding when I move model code to another thread, because I can't count on the update system to really work. While I find data binding to be a great concept, I think the opaqueness of the data binding system has been a real hindrance for my adoption of it. (Sorry for the rant!) Thanks again, Adam.