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  • What is the standard convention for defining nested view:viewmodel mapping in MVVM Light

    - by firoso
    so in classic MVVM examples ive seen DataTemplate definitions are used to map up View Models to Views, what is the standard way to do this in MVVM Light framework, and where should the mappings be located? Following are examples of what I'm doing now and what I'm talking about, blendability is important to me! Main Window: <Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" x:Class="STS2Editor.MainWindow" Title="{Binding ApplicationTitle, Mode=OneWay}" DataContext="{Binding RootViewModel, Source={StaticResource Locator}}"> <Window.Resources> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="Skins/ApplicationSkin.xaml" /> <ResourceDictionary Source="Resources/ViewMappings.xaml" /> </ResourceDictionary.MergedDictionaries> </ResourceDictionary> </Window.Resources> <Grid> <ContentControl Content="{Binding ApplicationManagementViewModel}" HorizontalAlignment="Left" VerticalAlignment="Top"/> </Grid> </Window> In the above code, my RootViewModel class has an instance of the class ApplicationManagementViewModel with the same property name: public ApplicationManagementViewModel ApplicationManagementViewModel {get {...} set {...} } I reference the ResourceDictionary "ViewMappings.xaml" to specify how my view model is represented as a view. <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:STS2Editor.ViewModel"> <DataTemplate DataType="{x:Type local:ApplicationManagementViewModel}"> <local:ApplicationManagementView/> </DataTemplate> </ResourceDictionary> should I be doing things like this using ViewModelLocator? what about collections of view models?

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  • WPF: How do I get a reference to a styled window control in code behind?

    - by Brad
    I have a window defined with a style: <Window x:Class="winBorderless" x:Name="winBorderless" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Local="clr-namespace:WindowStyle" Style="{StaticResource Window_Cartesia}" WindowStartupLocation="CenterScreen" BorderThickness="1" BorderBrush="#FF9CAAC1" Margin="5" Title="[Document Title]"> and the style defined in an application level dictionary: <Style x:Key="Window_Cartesia" TargetType="{x:Type Window}"> <Setter Property="WindowStyle" Value="None"/> <Setter Property="AllowsTransparency" Value="True"/> <Setter Property="Background" Value="Transparent"/> <EventSetter Event="Loaded" Handler="Loaded"/> <EventSetter Event="PreviewKeyDown" Handler="Preview_KeyDown"/> <EventSetter Event="MouseMove" Handler="FullScreen_MouseMove"/> <Setter Property="Template"> In code behind I have a reference to the Window instance set: Win = DirectCast(sender, winBorderless) This allows access to the window properties as the EventSetters pass references to the various controls. However, it doesn't provide for access to the controls defined in the style through the window reference as they don't exist there. So, what is the best way to reference a control through code behind that is defined in the style. I'd prefer not to iterate the trees to find them but ya gotta do....

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  • Loading and binding a serialized view model to a WPF window?

    - by generalt
    Hello all. I'm writing a one-window UI for a simple ETL tool. The UI consists of the window, the code behind for the window, a view model for the window, and the business logic. I wanted to provide functionality to the users to save the state of the UI because the content of about 10-12 text boxes will be reused between sessions, but are specific to the user. I figured I could serialize the view model, which contains all the data from the textboxes, and this works fine, but I'm having trouble loading the information in the serialized XML file back into the text boxes. Constructor of window: public ETLWindow() { InitializeComponent(); _viewModel = new ViewModel(); this.DataContext = _viewModel; _viewModel.State = Constants.STATE_IDLE; Loaded += new RoutedEventHandler(MainWindow_Loaded); } XAML: <TextBox x:Name="targetDirectory" IsReadOnly="true" Text="{Binding TargetDatabaseDirectory, UpdateSourceTrigger=PropertyChanged}"/> ViewModel corresponding property: private string _targetDatabaseDirectory; [XmlElement()] public string TargetDatabaseDirectory { get { return _targetDatabaseDirectory; } set { _targetDatabaseDirectory = value; OnPropertyChanged(DataUtilities.General.Utilities.GetPropertyName(() => new ViewModel().TargetDatabaseDirectory)); } Load event in code behind: private void loadState_Click(object sender, RoutedEventArgs e) { string statePath = this.getFilePath(); _viewModel = ViewModel.LoadModel(statePath); } As you can guess, the LoadModel method deserializes the serialized file on the user's drive. I couldn't find much on the web regarding this issue. I know this probably has something to do with my bindings. Is there some way to refresh on the bindings on the XAML after I deserialize the view model? Or perhaps refresh all properties on the view model? Or am I completely insane thinking any of this could be done? Thanks.

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  • Is there a way to touch-enable scrolling in a WPF ScrollViewer?

    - by Brian Sullivan
    I'm trying to create a form in a WPF application that will allow the user to use iPhone-like gestures to scroll through the available fields. So, I've put all my form controls inside a StackPanel inside a ScrollViewer, and the scrollbar shows up as expected when there are too many elements to be shown on the screen. However, when I try to test this on my touch-enabled device, a panning gesture (placing a finger down on the surface and dragging it upward) does not move the viewable area down as I would expect. When I simply put a number of elements inside a ListView, the touch gestures work just fine. Is there any way to enable the same kind of behavior in a ScrollViewer? My window is structured like this: <Window x:Class="TestTouchScrolling.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525" Loaded="Window_Loaded"> <Grid> <ScrollViewer Name="viewer" VerticalScrollBarVisibility="Auto"> <StackPanel Name="panel"> <StackPanel Orientation="Horizontal"> <Label>Label 1:</Label> <TextBox Name="TextBox1"></TextBox> </StackPanel> <StackPanel Orientation="Horizontal"> <Label>Label 2:</Label> <TextBox Name="TextBox2"></TextBox> </StackPanel> <StackPanel Orientation="Horizontal"> <Label>Label 3:</Label> <TextBox Name="TextBox3"></TextBox> </StackPanel> <!-- Lots more like these --> </StackPanel> </ScrollViewer> </Grid>

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  • Problem with mouse event on a user control (wpf).

    - by csciguy
    All, I have a user control, defined as follows. <UserControl x:Class="IDOView.AnimatedCharacter" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:local="clr-namespace:IDOView" mc:Ignorable="d" Background="Transparent" > <Image Name="displayImage" Height="Auto" Width="Auto" Stretch="Fill" IsHitTestVisible="True"/> The control is added to a main page twice, as follows. <local:customControl x:Name="A1" Height="259" Width="197" DisplayImage="circle.png" Canvas.Left="-279" Canvas.Top="-56" MouseLeftButtonUp="DoA1"> <local:customControl x:Name="A1" Height="259" Width="197" DisplayImage="square.png" Canvas.Left="-209" Canvas.Top="-56" MouseLeftButtonUp="DoA2"> Essentially, about half of the circle is behind the square. I need the square image in this case to pass through events to the circle behind it. The square has an element cut out of it (transparent). What is happening now is that the circle event only registers if I click on the region that is not covered by the square. Surely there has to be a way to bubble this event, or click-through?

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  • Podcast: The Invisible UI : Natural User Interfaces with Josh Blake

    - by craigshoemaker
    Josh Blake of Infostrat joins Pixel8 to discuss NUI development in .NET. Josh is the author of the upcoming book Multitouch on Windows from Manning. Reaching far beyond theory and the niche market of Microsoft Surface, NUI development is now possible with Silverlight and WPF development on Windows 7 and Windows 7 Mobile devices. Subscribe to the podcast! The Natural User Interface (NUI) was a prominent force at MIX10. What is NUI? Wikipedia defines it as: Natural user interface, or NUI, is the common parlance used by designers and developers of computer interfaces to refer to a user interface that is effectively invisible, or becomes invisible with successive learned interactions, to its users. The word natural is used because most computer interfaces use artificial control devices whose operation has to be learned. A NUI relies on a user being able to carry out relatively natural motions, movements or gestures that they quickly discover control the computer application or manipulate the on-screen content. The most descriptive identifier of a NUI is the lack of a physical keyboard and/or mouse. In our interview Josh demystifies what NUI is, makes a distinction between gestures and manipulations, and talks about what is possible today for NUI development. For more from Josh make sure to check out his book: and watch his MIX Presentation: Developing Natural User Interfaces with Microsoft Silverlight and WPF 4 Touch Resources Mentioned in the Show Check out the following videos that show the roots and future of NUI development: Jeff Han's Multi-Touch TED Presentation Microsoft Surface Project Natal MIX10 Day 2 Keynote A few times during our talk Bill Buxton’s work is mentioned. To see his segment of the MIX10 day 2 keynote, click below:

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  • C# 5.0 Async/Await Demo Code

    - by Paulo Morgado
    I’ve published the sample code I use to demonstrate the use of async/await in C# 5.0. You can find it here. Projects PauloMorgado.AyncDemo.WebServer This project is a simple web server implemented as a console application using Microsoft ASP.NET Web API self hosting and serves an image (with a delay) that is accessed by the other projects. This project has a dependency on Json.NET due to the fact the the Microsoft ASP.NET Web API hosting has a dependency on Json.NET. The application must be run on a command prompt with administrative privileges or a urlacl must be added to allow the use of the following command: netsh http add urlacl url=http://+:9090/ user=machine\username To remove the urlacl, just use the following command: netsh http delete urlacl url=http://+:9090/ PauloMorgado.AsyncDemo.WindowsForms This Windows Forms project contains three regions that must be uncommented one at a time: Sync with WebClient This code retrieves the image through a synchronous call using the WebClient class. Async with WebClient This code retrieves the image through an asynchronous call using the WebClient class. Async with HttpClient with cancelation This code retrieves the image through an asynchronous call with cancelation using the HttpClient class. PauloMorgado.AsyncDemo.Wpf This WPF project contains three regions that must be uncommented one at a time: Sync with WebClient This code retrieves the image through a synchronous call using the WebClient class. Async with WebClient This code retrieves the image through an asynchronous call using the WebClient class. Async with HttpClient with cancelation This code retrieves the image through an asynchronous call with cancelation using the HttpClient class.

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  • Reference a internal class from a Windows Workflow Activity

    - by Ben Hughes
    I'm creating a custom Workflow activity for use within TFS2010. In the same assembly I have a XAML activity and a C# code activity. The XAML activity references the code activity. When the assembly is deployed to our clients, I only want them to be able to use the Workflow activity. The code activity is of little use by itself and would no doubt confuse them. I thought the logical way to do this would be to set the code activity class to internal: the XAML is in the same assembly and should be able to access it. However, when I do that I get an error in the XAML saying that the assembly can't be found. Is there a way to make activities internal/hidden?

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  • What is the correct UI interface to learn for creating Windows phone 8 apps? [closed]

    - by Robert Oschler
    I am a veteran Delphi 6 programmer transitioning to C# development. My first project is a open source library that will have a minimal user interface since it is meant to be used as a Component primarily on desktop PCs running Visual Studio. My next project is going to be a Windows 8 phone app and I intend for that platform to be my primary focus for future C# development, not the desktop. My concern is that I waste as little time as possible learning a presentation framework that will benefit or distract me from writing Windows 8 phone apps. The plethora of framework names I have already encountered include, WinForms, WPF (Windows Presentation Framework), Silverlight, Silverlight Mobile, Metro and there may be others. Given my goal outlined in the first paragraph above, I have a few questions: 1) Which of the frameworks should I use for the small amount of UI work I will do with the desktop Component project that will help me the most, or hurt me the least, when I move to Windows 8 phone app development? 2) Which is the correct framework to study for developing Windows 8 phone apps? 3) Any awesome tutorials, resources or books you have run into targeted towards veteran programmers from other platforms? I read about the Portable Library Tools on this Stack Overflow thread: http://stackoverflow.com/questions/5522355/windows-phone-7-wpf-sharing-a-codebase But the reply by Simon Guindon seemed to indicate to me that it's not the best solution for writing a competitive Windows 8 phone app.

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  • How to add multiple handlers to an attached event in XAML ?

    - by Gishu
    I want to add 2 handlers to a particular event like shown above. However this won't compile - 'attribute can be set more than once'. I have multiple methods because they do different things (are named appropriately). e.g. the first handler has nothing in common with the second. My other option was to kludge a SetFlagForCursorTrackingAndCheckForViewLink method - which is "Yech!". Any ideas ?

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  • WPF XAML: How to trigger style change in ListBoxItem ancestor to user class?

    - by dhovel
    I have an ObservableCollection of items of my class "PlaylistItem" that implements INotifyPropertyChanged. The collection is databound to a ListBox and everything else is working. I want to know what markup to use to trigger a style change of the wrapping ListBoxItem based on a property (e.g. "Playing", bool) of the PlaylistItem. How to I use FindAncestor to trigger the change? I can to this in code, but I know I that I can (somehow) do it in markup. Thanks in advance.

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  • Metro style apps with Html and C#

    - by labroo
    According to this slide http://geekswithblogs.net/images/geekswithblogs_net/technetbytes/windows-8-platform-tools.jpg Does it mean I have to use XAML view with C# if I want to develop a metro styled application? Can I use a HTML/JS/CSS - C# combination with event handlers and all? Something like ASP.NET Webforms/MVC . I know it is not the same client server architecture, but since metro styled apps support HTML/JS, I was wondering. I can use Win-JS. But can I rather write C# than Javascript, and use HTML rather than XAML?(I dont know XAML and I like C#) All the C# samples I found online use XAML.

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  • Generic usercontrol possible?

    - by Sam
    Since .Net 4 does support generics in XAML, I'd like to create a UserControl using generics, like: public class MyComboBox<T> { } I can declare the UserControl quite well, but how would I use it in a XAML file? Or can't this be done in XAML?

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  • Q1 2010 New Feature: Paging with RadGridView for Silverlight and WPF

    We are glad to announce that the Q1 2010 Release has added another weapon to RadGridViews growing arsenal of features. This is the brand new RadDataPager control which provides the user interface for paging through a collection of data. The good news is that RadDataPager can be used to page any collection. It does not depend on RadGridView in any way, so you will be free to use it with the rest of your ItemsControls if you chose to do so. Before you read on, you might want to download the samples solution that I have attached. It contains a sample project for every scenario that I will discuss later on. Looking at the code while reading will make things much easier for you. There is something for everyone among the 10 Visual Studio projects that are included in the solution. So go and grab it. I. Paging essentials The single most important piece of software concerning paging in Silverlight is the System.ComponentModel.IPagedCollectionView interface. Those of you who are on the WPF front need not worry though. As you might already know, Teleriks Silverlight and WPF controls is share the same code-base. Since WPF does not contain a similar interface, Telerik has provided its own Telerik.Windows.Data.IPagedCollectionView. The IPagedCollectionView interface contains several important members which are used by RadGridView to perform the actual paging. Silverlight provides a default implementation of this interface which, naturally, is called PagedCollectionView. You should definitely take a look at its source code in case you are interested in what is going on under the hood. But this is not a prerequisite for our discussion. The WPF default implementation of the interface is Teleriks QueryableCollectionView which, among many other interfaces, implements IPagedCollectionView. II. No Paging In order to gradually build up my case, I will start with a very simple example that lacks paging whatsoever. It might sound stupid, but this will help us build on top of this paging-devoid example. Let us imagine that we have the simplest possible scenario. That is a simple IEnumerable and an ItemsControl that shows its contents. This will look like this: No Paging IEnumerable itemsSource = Enumerable.Range(0, 1000); this.itemsControl.ItemsSource = itemsSource; XAML <Border Grid.Row="0" BorderBrush="Black" BorderThickness="1" Margin="5">     <ListBox Name="itemsControl"/> </Border> <Border Grid.Row="1" BorderBrush="Black" BorderThickness="1" Margin="5">     <TextBlock Text="No Paging"/> </Border> Nothing special for now. Just some data displayed in a ListBox. The two sample projects in the solution that I have attached are: NoPaging_WPF NoPaging_SL3 With every next sample those two project will evolve in some way or another. III. Paging simple collections The single most important property of RadDataPager is its Source property. This is where you pass in your collection of data for paging. More often than not your collection will not be an IPagedCollectionView. It will either be a simple List<T>, or an ObservableCollection<T>, or anything that is simply IEnumerable. Unless you had paging in mind when you designed your project, it is almost certain that your data source will not be pageable out of the box. So what are the options? III. 1. Wrapping the simple collection in an IPagedCollectionView If you look at the constructors of PagedCollectionView and QueryableCollectionView you will notice that you can pass in a simple IEnumerable as a parameter. Those two classes will wrap it and provide paging capabilities over your original data. In fact, this is what RadGridView does internally. It wraps your original collection in an QueryableCollectionView in order to easily perform many useful tasks such as filtering, sorting, and others, but in our case the most important one is paging. So let us start our series of examples with the most simplistic one. Imagine that you have a simple IEnumerable which is the source for an ItemsControl. Here is how to wrap it in order to enable paging: Silverlight IEnumerable itemsSource = Enumerable.Range(0, 1000); var pagedSource = new PagedCollectionView(itemsSource); this.radDataPager.Source = pagedSource; this.itemsControl.ItemsSource = pagedSource; WPF IEnumerable itemsSource = Enumerable.Range(0, 1000); var pagedSource = new QueryableCollectionView(itemsSource); this.radDataPager.Source = pagedSource; this.itemsControl.ItemsSource = pagedSource; XAML <Border Grid.Row="0"         BorderBrush="Black"         BorderThickness="1"         Margin="5">     <ListBox Name="itemsControl"/> </Border> <Border Grid.Row="1"         BorderBrush="Black"         BorderThickness="1"         Margin="5">     <telerikGrid:RadDataPager Name="radDataPager"                               PageSize="10"                              IsTotalItemCountFixed="True"                              DisplayMode="All"/> This will do the trick. It is quite simple, isnt it? The two sample projects in the solution that I have attached are: PagingSimpleCollectionWithWrapping_WPF PagingSimpleCollectionWithWrapping_SL3 III. 2. Binding to RadDataPager.PagedSource In case you do not like this approach there is a better one. When you assign an IEnumerable as the Source of a RadDataPager it will automatically wrap it in a QueryableCollectionView and expose it through its PagedSource property. From then on, you can attach any number of ItemsControls to the PagedSource and they will be automatically paged. Here is how to do this entirely in XAML: Using RadDataPager.PagedSource <Border Grid.Row="0"         BorderBrush="Black"         BorderThickness="1" Margin="5">     <ListBox Name="itemsControl"              ItemsSource="{Binding PagedSource, ElementName=radDataPager}"/> </Border> <Border Grid.Row="1"         BorderBrush="Black"         BorderThickness="1"         Margin="5">     <telerikGrid:RadDataPager Name="radDataPager"                               Source="{Binding ItemsSource}"                              PageSize="10"                              IsTotalItemCountFixed="True"                              DisplayMode="All"/> The two sample projects in the solution that I have attached are: PagingSimpleCollectionWithPagedSource_WPF PagingSimpleCollectionWithPagedSource_SL3 IV. Paging collections implementing IPagedCollectionView Those of you who are using WCF RIA Services should feel very lucky. After a quick look with Reflector or the debugger we can see that the DomainDataSource.Data property is in fact an instance of the DomainDataSourceView class. This class implements a handful of useful interfaces: ICollectionView IEnumerable INotifyCollectionChanged IEditableCollectionView IPagedCollectionView INotifyPropertyChanged Luckily, IPagedCollectionView is among them which lets you do the whole paging in the server. So lets do this. We will add a DomainDataSource control to our page/window and connect the items control and the pager to it. Here is how to do this: MainPage <riaControls:DomainDataSource x:Name="invoicesDataSource"                               AutoLoad="True"                               QueryName="GetInvoicesQuery">     <riaControls:DomainDataSource.DomainContext>         <services:ChinookDomainContext/>     </riaControls:DomainDataSource.DomainContext> </riaControls:DomainDataSource> <Border Grid.Row="0"         BorderBrush="Black"         BorderThickness="1"         Margin="5">     <ListBox Name="itemsControl"              ItemsSource="{Binding Data, ElementName=invoicesDataSource}"/> </Border> <Border Grid.Row="1"         BorderBrush="Black"         BorderThickness="1"         Margin="5">     <telerikGrid:RadDataPager Name="radDataPager"                               Source="{Binding Data, ElementName=invoicesDataSource}"                              PageSize="10"                              IsTotalItemCountFixed="True"                              DisplayMode="All"/> By the way, you can replace the ListBox from the above code snippet with any other ItemsControl. It can be RadGridView, it can be the MS DataGrid, you name it. Essentially, RadDataPager is sending paging commands to the the DomainDataSource.Data. It does not care who, what, or how many different controls are bound to this same Data property of the DomainDataSource control. So if you would like to experiment with this, you can throw in any number of other ItemsControls next to the ListBox, bind them in the same manner, and all of them will be paged by our single RadDataPager. Furthermore, you can throw in any number of RadDataPagers and bind them to the same property. Then when you page with any one of them will automatically update all of the rest. The whole picture is simply beautiful and we can do all of this thanks to WCF RIA Services. The two sample projects (Silverlight only) in the solution that I have attached are: PagingIPagedCollectionView PagingIPagedCollectionView.Web IV. Paging RadGridView While you can replace the ListBox in any of the above examples with a RadGridView, RadGridView offers something extra. Similar to the DomainDataSource.Data property, the RadGridView.Items collection implements the IPagedCollectionView interface. So you are already thinking: Then why not bind the Source property of RadDataPager to RadGridView.Items? Well thats exactly what you can do and you will start paging RadGridView out-of-the-box. It is as simple as that, no code-behind is involved: MainPage <Border Grid.Row="0"         BorderBrush="Black"         BorderThickness="1" Margin="5">     <telerikGrid:RadGridView Name="radGridView"                              ItemsSource="{Binding ItemsSource}"/> </Border> <Border Grid.Row="1"         BorderBrush="Black"         BorderThickness="1"         Margin="5">     <telerikGrid:RadDataPager Name="radDataPager"                               Source="{Binding Items, ElementName=radGridView}"                              PageSize="10"                              IsTotalItemCountFixed="True"                              DisplayMode="All"/> The two sample projects in the solution that I have attached are: PagingRadGridView_SL3 PagingRadGridView_WPF With this last example I think I have covered every possible paging combination. In case you would like to see an example of something that I have not covered, please let me know. Also, make sure you check out those great online examples: WCF RIA Services with DomainDataSource Paging Configurator Endless Paging Paging Any Collection Paging RadGridView Happy Paging! Download Full Source Code Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • How to make creating viewmodels at runtime less painful

    - by Mr Happy
    I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painful. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genius since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use a DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an in-depth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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  • MVVM - how to make creating viewmodels at runtime less painfull

    - by Mr Happy
    I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painfull. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genious since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use an DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an indepth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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  • A strange bug of Blend 4 RC

    - by brainbox
     We've been breaking our heads about a week because blend 4 RC stop showing visual states of controls in design view.Here is the simple blend project with single button style inside app.xaml. Could anybody see visual states changes of this button style in blend? 

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  • How to make creating viewmodels at runtime less painfull

    - by Mr Happy
    I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painfull. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genious since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use an DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an indepth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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  • Silverlight Visual Studio XAML Design view not working

    - by Piyush
    I have installed visual studio 2008 sp1, silverlight tools, silverlight sdk, silverlight toolkit 2009 but still when I open silverlight application silverlight tools are not showing on my tool window as well as silverlight XAML Design view(color code formate) is not working. Whole xaml code is coming in black color.

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