I have a Contact entity that exposes a navigation proeprty for child Phone entities.
Public Class Contact : Inherits EntityObject
Public Property Phones() As EntityCollection(Of Phone)
EndClass
I want to Xamly retrieve the first phone of the bound contact.
I tried the following but it doesn't work.
Note: I also tried Phones[0] (I use VB).
<DataTemplate DataType="{x:Type data:Contact}">
<TextBlock Text="{Binding Phones(0)}"/>
</DataTemplate>
Any suggestions (either in VB or C# will be welcommed)?
In this link I found interesting solutions.
I am still opened to hear about new 'Xamly' ideas, that doesn't have to involve converters etc.
TheJeffro's one looks the best, and this is what I am using till further posts.
Related
In my MVVM Light application I do a search in a customer list. The search narrows the customer list which are displayed in a master/detail view with a datagrid (the master CustomerSearchResultView) and a separately defined usercontrol with FirstName, Lastname, Address etc, etc (the detail - CustomerSearchDetailView). Here are the main content of the master/detail view:
<StackPanel MinWidth="150" >
<TextBlock Text="Customer Search Result List" />
<Grid>
<DataGrid Name="CustomerList" ItemsSource="{Binding SearchResult}" SelectedItem="{Binding SelectedRow, Mode=TwoWay}" >
.....
</DataGrid>
</Grid>
<Grid Grid.Column="2">
<TextBlock Text="Customer Details" Style="{StaticResource Heading2}" Margin="30,-23,0,0"/>
<content:CustomerSearchDetail DataContext="{Binding SelectedRow}" />
</Grid>
</Grid>
</StackPanel>
Both have their corresponding ViewModels. Please remark the DC for the CustomerSearchDetail, SelectedRow - it is a property on the CustomerSearchResultViewModel and is defined like this:
private Customer _selectedRow;
...
public Customer SelectedRow
{
get { return _selectedRow; }
set
{
_selectedRow = value;
RaisePropertyChanged("SelectedRow");
}
}
...
Because of this I have not defined any DC on the CustomerSearchDetailView - it is set in the Binding on the "Master" view (as shown above) and it seems to work ok.
In my Model folder I have created the Customer class that is in use here. It implements ObservableObject and IDataErrorInfo and have public properties that raisepropertychanged events.
I run the application and everything seems to be ok. Note: the ViewModel for the CustomerSearchDetailView (that is CustomerSearchDetailViewModel.cs) is at this stage just an empty shell and not in use (as far as I can see ... the constructor is never accessed)
Now I want to add Save/Update functionality to my customer in the detail view. Ok, I add a Save button to the CustomerSearchDetailView like this:
<Button Content="Save" Command="{Binding Path = SaveCommand}" Width="80" Margin="0,0,15,0"/>
I create my "SaveCommand" RelayCommand property in my CustomerSearchDetailViewModel - but it is never accessed.
Hmmmmm ... well after some googling back and forth I come up with this:
<Button Content="Save" Command="{Binding Source={StaticResource MyCustDetails}, Path = SaveCommand}" Width="80" Margin="0,0,15,0"/>
I defined the "MyCustDetails" as a resource in this view pointing to the CustomerSearchDetailViewModel. And voila! I now hit the method when debugging ... but alas, my customer was of course "null". (In fact I spent 2 hours implementing the CommandParameter here and binding it to the "SelectedRow" Property on the master view - but the customer was still "null").
More googling and searching for mvvm examples, and I implemented my "SaveCommand" on the Customer class (the model object). And guess what? The edited customer got passed along - I could send it to my EF layer and everything seems to be ok ....
And - If you are still with me - here comes my questions:
1.) I would like - and thought that was the "proper MVVM way" of doing things - to have my CRUD/Repository accessing in the ViewModel. How can I do that in my scenario?
2.) Now that I have my CRUD in place via the Model class (Customer) - should i bother with question 1? In fact I have deleted the CustomerSearchDetailViewModel and everything runs ok. I feel I have invented the View - Model (MV) framework ... :-P
I would very much like feedback on this - and I apologize for this "wall of text".
Assuming DC means DataContext
Just my opinion:
First question is are you doing anything special with SelectedRow in CustomerSearchResultViewModel?
If the answer is no, just get rid of that property and have your CustomSearchDetailView bind directly to the DataGrid using {Binding ElementName=CustomerList, Path=SelectedItem}
Now your Save / update Commands need to be used by Button's in CustomerSearchDetailView. So instantly I'd be inclined to using a separate VM for that View and have these Command's defined there.
Now you mentioned these Commands were not accessed. Well the answer for that is because in your program you're never actually creating the CustomerSearchDetailViewModel.
Normal operation is your View's DataContext is it's VM(If it requires one. In your case you do imo cos you need it to hold your Commands)
looking at your code I'd guess your using MVVM Light. So in ViewModelLocator you have your Main property and in your Main View, you got the DataContext set using that Main property and Source={StaticResource Locator} where Locator is the ViewModelLocator created in App.xaml Resources. This thereby creates that ViewModel for that view defining that DataContext. You can ofcourse do the same in code-behind but let's not go off topic.
So in your case you got the DataContext set as SelectedRow which is of type Customer and Binding's are resolved using DataContext and that's why when your command's are defined in Customer it works fine but when it's in the VM it did not.
So why did it work when you had the commands in your VM and used
<Button Content="Save" Command="{Binding Source={StaticResource MyCustDetails}, Path = SaveCommand}" Width="80" Margin="0,0,15,0"/>
^^ That worked because the DataContext was not used since Source has been specified explicitly. and where-ever MyCustDetails was defined in resources, there the VM got created.
So it worked what's wrong with that?
Well it's quite a big mess. Also just like you mentioned Customer details in that VM was null. Well I hope you can guess why that was by now. It's because your VM was created in resources via x:Key="MyCustDetails" but nothing in it was ever used or set apart from when the Binding's referred to it explicitly
In this system we got commands that refer either to the Model which is plain wrong or the VM which is created as a resource just for this purpose. The DataContext is heavily linked to the "SearchResults" view making it not so easy for future extensions or layout updates.
If we keep the View <-> VM a 1 <-> 1 relattion we can avoid all this confusion. So in summary we can answer both your question's together. While this works, please don't let your code be like this and tweak it to better help expansion for future and comply with some basic guidelines.
So how do we do that?
Approach 1:
In your CustomerSearchDetail View, add a DependencyProperty of type Customer lets call this say SelectedCustomer.
Now replace DataContext="{Binding SelectedRow}" with SelectedCustomer="{Binding SelectedRow}" in CustomerSearchResultView
Now set the DataContext of your CustomerSerachDetailView as it's VM similar to how CustomerSerachResultsView links to it's VM(guessing through DataContext Binding in xaml using the ViewModelLocator)
Now you can have your commands in Button's of CustomerSerachDetailView just as <Button Command="{Binding SaveCommand}" ...
Finally because SelectedRow is no longer the DataContext of the CustomerSerachDetailsView, your Bindings for FirstName, Lastname, Address will all appear to stop working.
We got plenty of options to address this.
First is to in each Binding use a RelativeSource FindAncestor binding pointing to CustomerSerachDetailsView and there via the CurrentCustomer DP(DependencyProperty) we created before get the appropriate field.
eg:
<TextBlock Text={Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:CustomerDetailsView}}, Path=CurrentCustomer.FirstName}" />
now if you have multiple properties this is gonna soon start getting annoying to type. So then pick a common ancestor(say 3 of these TextBlocks are grouped under a StackPanel) and apply it's DataContext as the CurrentCustomer element via a similar binding to ^^. Now the StackPanel's children DataContext will be the Customer element so in each of their binding's you don't have to do the whole RelativeSource thing and can just mention {Binding Path=FirstName} and so on.
That's it. Now you got two view's with their own respective VM and a Model(Customer) and each have their respective tasks.
Great, we done? err not quite yet.
While Approach 1 is better than what we started with it's still just "meh". We could do better.
Approach 2
MVVMLight has a Messenger class that will allow you to communicate between different classes in a weak dependent format. You need to look into this if you haven't already.
So what do we do with Messenger?
pretty simple:
In the setter of SelectedRow in CustomerSearchResultsViewModel we'll send a message with the new incoming value to CustomerSearchDetailsViewModel.
Now in CustomerSearchResultsViewModel we'll add a property CurrentCustomer and assign it this incoming value.
In the CustomerSerachDetailsView we no longer create a DP. Which means we no longer set SelectedRow to anything(DataContext or DP) in the CustomerSerachDetailsView from CustomerSearchResultsView ( sweet less work :) )
As for the way we assign DataContext of CustomerSerachDetailsView or way we bind the Button.Command - They remain same as Approach 1
Finally the actual "FirstName" and so Binding's. Well now CurrentCustomer is a property of the CustomerSearchDetailsViewModel. So binding to it just like how the Button bind's to it's commands
^^ this works fine now cos DataContext for the TextBlock is the VM and the property CurrentCustomer exists in it.
I want use the MahApps PanoramaControl to display a bunch of photo's. However I see only the string paths appear in the control, which will be correct if you look at my code.
But I can't figure out howto get it working to show the images instead of the links.
Xaml:
<Controls:Panorama Grid.Row="2"
Grid.ColumnSpan="4"
ItemBox="140"
ItemsSource="{Binding PhotoCollection, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
ViewModel:
string[] filePaths = Directory.GetFiles(#"D:\Google Drive\Images\Backgrounds");
test = new PanoramaGroup("My Photo's", filePaths);
PhotoCollection = new ObservableCollection<PanoramaGroup> { test };
Anyone an idea on how to make it show the images? The control is load as I can scroll sideways on the text.
There is not much documentation on their site on how to get it working...
Or are you using some other Metro style lib for the 4.0 framework?
In order to get MahApps Panorama control i would offer the follow solution below. As to other frameworks that provide this level of detailed MODERN UI experience I have not come across any but interested to know if you do.
Hope the solutions works for you.
You need to add a Data Template the represent the object you're showing.
Start off by defining the object in a POCO class (as illustrated below). Then in the population of the items ensure you translate them to the newly created POCO object instead of leaving them as string values.
public class Photo {
public string Path { get; set; }
}
Next in the definition of you XAML window you need to create a reference to the namespace where the POCO object resides.
xmlns:model="clr-namespace:project.models;assembly=project"
Last, but not least, you want to then create a DataTemplate to represent the object. This is added to the window resources.
<Window.Resources>
<DataTemplate DataType="{x:Type model:Photo}">
<Image Source="{Binding Path}"/>
</DataTemplate>
</Window.Resources>
This should then let the render take place in the interface where it belongs. Hope this works for you.
I am developing an Application with the following layout,
I have no knowledge of MVVM and I'm on a tight timeline.
The Red area on the right is a ContentControl.
The area on the left will be a sidebar for Navigation
My question is
should I follow this aproach
http://channs.blogspot.com/2010/09/wpf-navigation.html OR
should I use MVVM light / Prism OR
should I use WPF pages?
I am currently inclined to option 1. Are there any pros and cons to it?
Which option would you recommend ?
My application will always have only one developer i.e. Me and it will contain about 30 screens.
Since you're on a tight schedule and have no knowledge of MVVM (or Prism?), then you'll be way better off using options 3 and 1. From my experience, it takes devs a long time to get up to speed on MVVM and Prism. Certain things that are taken for granted, become much more difficult in the MVVM/Prism world.
With that being said, I'm a huge advocate of MVVM/Prism and feel that it's well worth the extra effort, especially for a project of your size. However, since you're pressured for time, don't bother, just do code-behind.
Prism takes time to learn, if you are on a tight deadline then I think you should just go with what you know, When you have time reading the prism book especially the section on navigation will be helpful.
Don't go with PRISM,that would be an overkill for such non complex apps. If you are familiar with DataBinding, that can save you a lot of time even without MVVM.Since you're in a hurry, I think you should go with what you already know and start learning MVVM at ease.Good luck
mvvm is not that hard. in your case you need first a mainviewmodel.
public class MainViewModel
{
private ICollectionView _myView {get;set;}
public ObservableCollection<MyModulWrapper> MyModules{get;set;}
public MyModulWrapper SelectedModul {get;set;}
public MainViewModel()
{
this.MyModules = new ObservableCollection<MyModulWrapper>();
//i use icollectionview because i often need sorting or filtering
this._myView = = CollectionViewSource.GetDefaultView(this.MyModules);
this._myView .CurrentChanged += (s, e) => { this.SelectedModul = this._myView .CurrentItem as MyModulWrapper; };
}
}
you have to fill(in any way - i use mef for my apps, but hardcoded its also ok) your collection with all modules(viewmodels) you wanna show on your top screen.
the MyModulWrapper just contain the viewmodel for your modul and a nice display name for your navigation.
public class MyModulWrapper
{
public string Displayname {get;set;}
public object Modul {get;set;}//instead of object you can take an interface or base class or whatever
}
now you have all to let the mainview run :) you just have to set the datacontext for the MainWindow to your MainViewModel.
mainwindow.xaml
<Window.Resources>
<!--for each viewmodel you wanna show create a datatemplate. so wpf knows how to render your viewmodel-->
<DataTemplate DataType={x:Type local:MyViewmodel4FirstButton>
<local:MyFirstButtonView />
</DataTemplate>
</Window.Resources>
<!-- for navigation -->
<ListBox ItemsSource="{Binding MyModules}"
SelectedItem="{Binding SelectedModul , Mode=OneWay}"
IsSynchronizedWithCurrentItem="true">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Displayname}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<!-- all you need to show your selected modul - if you have a DATATEMPLATEs!! -->
<ContentControl Content="{Binding SelectedModul }"/>
all your viewmodels have to implement INotifyPropertyChanged of course, and raise it properly.
ps: code is written without IDE so ignore errors^^
I am working on a dynamic search view wherein clicking a button should add a new row containing 3 combobox and 2 textboxes.
How should I go about doing this?
If you really want to do mvvm , try to forget "how can I add controls". You don't have to, just think about your viewmodels - WPF create the contols for you :)
In your case lets say we have a SearchViewModel and a SearchEntryViewmodel.
public class SearchEntryViewmodel
{
//Properties for Binding to Combobox and Textbox goes here
}
public class SearchViewModel
{
public ObservableCollection<SearchEntryViewmodel> MySearchItems {get;set;}
public ICommand AddSearchItem {get;}
}
Till now you dont have to think about usercontrols/view. In your SearchView you create an ItemsControl and bind the ItemsSource to MySearchItems.
<ItemsControl ItemsSource="{Binding MySearchItems}"/>
You see now all of your SearchEntryViewmodels in the ItemsControl(just the ToString() atm).
To fit your requirements to show every SearchEntryViewmodel with 3Comboboxes and so on you just have to define a DataTemplate in your Resources
<DataTemplate DataType="{x:Type local:SearchEntryViewmodel}">
<StackPanel Orientation="Horizontal">
<Combobox ItemsSource="{Binding MyPropertyInSearchEntryViewmodel}"/>
<!-- the other controls with bindings -->
</StackPanel>
</DataTemplate>
That's all :) and you never have to think about "how can I add controls dynamically?". You just have to add new SearchEntryViewmodel to your collection.
This approach is called Viewmodel First and I think it's the easiest way to do MVVM.
One option is that you can create TextBoxes and comboboxes in backend by creating a new instanse.
But the better option is that you can create one usercontrol which contains All texboxes and comboboxes which you want to add and in which format you want.
After creating when the button is pressed you can create a instace of this usercontrol and set it in the grid or any other control by using SetValue property of the control.
If you are new to WPF and MVVM this read this blogs to understand this.
https://radhikakhacharia.wordpress.com/2012/06/01/wpf-tutorial-3/
https://radhikakhacharia.wordpress.com/2012/02/13/model-view-viewmodel/
If you are new to both MVVM and WPF, there is a really wonderful video tutorial on how to
architect a C# / WPF / MVVM application by Jason Dollinger which is available here on lab49. All of the sourcecode he developes in this amazing video is available also right here on lab49.
After watching it, you will not have any problems developing your search view for sure.
Can anyone point me to a good resource (or throw me a clue) to show me how to do DataBinding to controls (ComboBox, ListBox, etc.) in WPF? I'm at a bit of a loss when all my WinForms niceities are taken away from me, and I'm not all that bright to start with...
The best resource I've found for WPF data binding is Bea Costa's blog. Start from the first post and read forward. It's awesome.
I find the tutorial videos at Windows Client .Net equally awesome. Dot Net Rocks TV has also covered it some time ago.
in code behind -- set the DataContext of your list box equal to the collection you're binding to.
private void OnInit(object sender, EventArgs e)
{
//myDataSet is some IEnumerable
// myListBox is a ListBox control.
// Set the DataContext of the ListBox to myDataSet
myListBox.DataContext = myDataSet;
}
In XAML, Listbox can declare which properties it binds to using the "Binding" syntax.
<ListBox Name="myListBox" Height="200"
ItemsSource="{Binding Path=BookTable}"
ItemTemplate ="{StaticResource BookItemTemplate}"/>
And some more links, just in case the above didn't suffice:
Windows Presentation Foundation - Data Binding How-to Topics
- Approx 30 'How To' articles from MSDN.
"The topics in this section describe how to use data binding to bind elements to data from a variety of data sources in the form of common language runtime (CLR) objects and XML. "
Moving Toward WPF Data Binding One Step at a Time
- By WPF guru Josh Smith
"This article explains the absolute basics of WPF data binding. It shows four different ways how to perform the same simple task. Each iteration moves closer to the most compact, XAML-only implementation possible. This article is for people with no experience in WPF data binding."
Here's another good resource from MSDN: Data Binding Overview.
There are three things you need to do:
Bind the ItemsSource of the ComboBox to the list of options.
Bind the SelectedItem to the property that holds the selection.
Set the ComboBox.ItemTemplate to a DataTemplate for a ComboBoxItem.
So, for example, if your data context object is a person having email addresses, and you want to choose their primary, you might have classes with these signatures:
public class EmailAddress
{
public string AddressAsString { get; set; }
}
public class Person
{
public IEnumerable<EmailAddress> EmailAddresses { get; }
public EmailAddress MainEmailAddress { get; set; }
}
Then you could create the combo box like this:
<ComboBox ItemsSource="{Binding EmailAddresses}" SelectedItem="{Binding MainEmailAddress}">
<ComboBox.ItemTemplate>
<DataTemplate>
<ComboBoxItem Content="{Binding AddressAsString}"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
Now you need to implement INotifyPropertyChanged in both Person and EmailAddress. For the EmailAddresses collection, you could back it with an ObjservableCollection.
Or as an alternative you can use Update Controls .NET. This is an open source project that replaces data binding and does not require INotifyPropertyChanged. You can use whatever collection makes sense to back the EmailAddresses property. The XAML works the same as above, except that you import the UpdateControls.XAML namespace and replace {Binding ...} with {u:Update ...}.