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  • Master Details and collectionViewSource in separate views cannot make it work.

    - by devnet247
    Hi all, I really cannot seem to make/understand how it works with separate views It all works fine if a bundle all together in a single window. I have a list of Countries-Cities-etc... When you select a country it should load it's cities. Works So I bind 3 listboxes successfully using collection sources and no codebehind more or less (just code to set the datacontext and selectionChanged). you can download the project here http://cid-9db5ae91a2948485.skydrive.live.com/self.aspx/PublicFolder/2MasterDetails.zip <Window.Resources> <CollectionViewSource Source="{Binding}" x:Key="cvsCountryList"/> <CollectionViewSource Source="{Binding Source={StaticResource cvsCountryList},Path=Cities}" x:Key="cvsCityList"/> <CollectionViewSource Source="{Binding Source={StaticResource cvsCityList},Path=Hotels}" x:Key="cvsHotelList"/> </Window.Resources> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition/> <ColumnDefinition/> </Grid.ColumnDefinitions> <Grid.RowDefinitions> <RowDefinition Height="Auto"/> <RowDefinition/> </Grid.RowDefinitions> <TextBlock Grid.Column="0" Grid.Row="0" Text="Countries"/> <TextBlock Grid.Column="1" Grid.Row="0" Text="Cities"/> <TextBlock Grid.Column="2" Grid.Row="0" Text="Hotels"/> <ListBox Grid.Column="0" Grid.Row="1" Name="lstCountries" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding Source={StaticResource cvsCountryList}}" DisplayMemberPath="Name" SelectionChanged="OnSelectionChanged"/> <ListBox Grid.Column="1" Grid.Row="1" Name="lstCities" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding Source={StaticResource cvsCityList}}" DisplayMemberPath="Name" SelectionChanged="OnSelectionChanged"/> <ListBox Grid.Column="2" Grid.Row="1" Name="lstHotels" ItemsSource="{Binding Source={StaticResource cvsHotelList}}" DisplayMemberPath="Name" SelectionChanged="OnSelectionChanged"/> </Grid> Does not work I am trying to implement the same using a view for each eg(LeftSideMasterControl -RightSideDetailsControls) However I cannot seem to make them bind. Can you help? I would be very grateful so that I can understand how you communicate between userControls You can download the project here. http://cid-9db5ae91a2948485.skydrive.live.com/self.aspx/PublicFolder/2MasterDetails.zip I have as follows LeftSideMasterControl.xaml <Grid> <ListBox Name="lstCountries" SelectionChanged="OnSelectionChanged" DisplayMemberPath="Name" ItemsSource="{Binding Countries}"/> </Grid> RightViewDetailsControl.xaml MainView.xaml <CollectionViewSource Source="{Binding}" x:Key="cvsCountryList"/> <CollectionViewSource Source="{Binding Source={StaticResource cvsCountryList},Path=Cities}" x:Key="cvsCityList"/> </UserControl.Resources> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition Width="3*"/> </Grid.ColumnDefinitions> <Views:LeftViewMasterControl x:Name="leftSide" Margin="5" Content="{Binding Source=}"/> <GridSplitter Grid.Column="0" Grid.Row="0" Background="LightGray"/> <Views:RightViewDetailsControl Grid.Column="1" x:Name="RightSide" Margin="5"/> </Grid> ViewModels public class CountryListVM : ViewModelBase { public CountryListVM() { Countries = new ObservableCollection<CountryVM>(); } public ObservableCollection<CountryVM> Countries { get; set; } private RelayCommand _loadCountriesCommand; public ICommand LoadCountriesCommand { get { return _loadCountriesCommand ?? (_loadCountriesCommand = new RelayCommand(x => LoadCountries(), x => CanLoadCountries)); } } private static bool CanLoadCountries { get { return true; } } private void LoadCountries() { var countryList = Repository.GetCountries(); foreach (var country in countryList) { Countries.Add(new CountryVM { Name = country.Name }); } } } public class CountryVM : ViewModelBase { private string _name; public string Name { get { return _name; } set { _name = value; OnPropertyChanged("Name"); } } } public class CityListVM : ViewModelBase { private CountryVM _selectedCountry; public CityListVM(CountryVM country) { SelectedCountry = country; Cities = new ObservableCollection<CityVM>(); } public ObservableCollection<CityVM> Cities { get; set; } public CountryVM SelectedCountry { get { return _selectedCountry; } set { _selectedCountry = value; OnPropertyChanged("SelectedCountry"); } } private RelayCommand _loadCitiesCommand; public ICommand LoadCitiesCommand { get { return _loadCitiesCommand ?? (_loadCitiesCommand = new RelayCommand(x => LoadCities(), x => CanLoadCities)); } } private static bool CanLoadCities { get { return true; } } private void LoadCities() { var cities = Repository.GetCities(SelectedCountry.Name); foreach (var city in cities) { Cities.Add(new CityVM() { Name = city.Name }); } } } public class CityVM : ViewModelBase { private string _name; public string Name { get { return _name; } set { _name = value; OnPropertyChanged("Name"); } } } Models ========= public class Country { public Country() { Cities = new ObservableCollection<City>(); } public string Name { get; set; } public ObservableCollection<City> Cities { get; set; } } public class City { public City() { Hotels = new ObservableCollection<Hotel>(); } public string Name { get; set; } public ObservableCollection<Hotel> Hotels { get; set; } } public class Hotel { public string Name { get; set; } }

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  • MVVM-Light Loaded Evented Executing Twice

    - by user275561
    Let me show the code first, The Control <ItemsControl.ItemsPanel> <ItemsPanelTemplate> <Controls:MatrixGrid x:Name="matrixGrid"> <i:Interaction.Triggers> <i:EventTrigger EventName="Loaded"> <cmd:EventToCommand Command="{Binding MatrixLoaded}" CommandParameter="{Binding ElementName=matrixGrid}" /> </i:EventTrigger> </i:Interaction.Triggers> </Controls:MatrixGrid> <ItemsControl.ItemsPanel> <ItemsPanelTemplate> In The ViewModel Class I have public RelayCommand<MatrixGrid> MatrixLoaded { get; private set; } In The Constructor of the View Model I have MatrixLoaded = new RelayCommand<MatrixGrid>(MatrixGridAction); Now When I put a Breakpoint on the Function MatrixGridAction, The breakpoint is hit twice. Am I doing something wrong or is this a bug?

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  • How to save the content of Textbox into a textfile

    - by Owais Wani
    I have a textbox which has some content. I also have a button (SAVE) which shud open the FileSaveDialog and allow the content to be saved in a .txt file. XAML: <TextBox Height="93" IsReadOnly="True" Text="{Binding Path=ReadMessage, Mode=TwoWay}" Name="MessageRead" /> <Button Content="Save" Command="{Binding Path=SaveFileCommand}" Name="I2CSaveBtn" /> ViewModel: private string _readMessage = string.Empty; public string ReadMessage { get { return _readMessage; } set { _readMessage = value; NotifyPropertyChanged("ReadMessage"); } } public static RelayCommand SaveFileCommand { get; set; } private void RegisterCommands() { SaveFileCommand = new RelayCommand(param => this.ExecuteSaveFileDialog()); } private void ExecuteSaveFileDialog() { //What To Do HERE??? } What I basically need is to read the content of textbox, open a file save dialog and store it in a text file to be saved in my system.

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  • Sample code for my #mix10 talk online

    - by Laurent Bugnion
    I just saw that the video for my MIX10 session is online already! Impressive work, MIX10 team. I also published the sample code on my web server, so here are the links: Powerpoint slides Video MVVM Demo 1 (start) MVVM Demo 1 (final) Command sample RelayCommand sample Messaging sample MVVM Demo 2 (start) MVVM Demo 2 (final) MVVM Light Toolkit Version 3 It was a real pleasure and an amazing experience to have this talk and to get all the great feedback! Thanks all for coming, and as usual don’t hesitate to send your feedback! Laurent

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  • What's the best way to expose a Model object in a ViewModel?

    - by Angel
    In a WPF MVVM application, I exposed my model object into my viewModel by creating an instance of Model class (which cause dependency) into ViewModel. Instead of creating separate VM properties, I wrap the Model properties inside my ViewModel Property. My model is just an entity framework generated proxy class: public partial class TblProduct { public TblProduct() { this.TblPurchaseDetails = new HashSet<TblPurchaseDetail>(); this.TblPurchaseOrderDetails = new HashSet<TblPurchaseOrderDetail>(); this.TblSalesInvoiceDetails = new HashSet<TblSalesInvoiceDetail>(); this.TblSalesOrderDetails = new HashSet<TblSalesOrderDetail>(); } public int ProductId { get; set; } public string ProductCode { get; set; } public string ProductName { get; set; } public int CategoryId { get; set; } public string Color { get; set; } public Nullable<decimal> PurchaseRate { get; set; } public Nullable<decimal> SalesRate { get; set; } public string ImagePath { get; set; } public bool IsActive { get; set; } public virtual TblCompany TblCompany { get; set; } public virtual TblProductCategory TblProductCategory { get; set; } public virtual TblUser TblUser { get; set; } public virtual ICollection<TblPurchaseDetail> TblPurchaseDetails { get; set; } public virtual ICollection<TblPurchaseOrderDetail> TblPurchaseOrderDetails { get; set; } public virtual ICollection<TblSalesInvoiceDetail> TblSalesInvoiceDetails { get; set; } public virtual ICollection<TblSalesOrderDetail> TblSalesOrderDetails { get; set; } } Here is my ViewModel: public class ProductViewModel : WorkspaceViewModel { #region Constructor public ProductViewModel() { StartApp(); } #endregion //Constructor #region Properties private IProductDataService _dataService; public IProductDataService DataService { get { if (_dataService == null) { if (IsInDesignMode) { _dataService = new ProductDataServiceMock(); } else { _dataService = new ProductDataService(); } } return _dataService; } } //Get and set Model object private TblProduct _product; public TblProduct Product { get { return _product ?? (_product = new TblProduct()); } set { _product = value; } } #region Public Properties public int ProductId { get { return Product.ProductId; } set { if (Product.ProductId == value) { return; } Product.ProductId = value; RaisePropertyChanged("ProductId"); } } public string ProductName { get { return Product.ProductName; } set { if (Product.ProductName == value) { return; } Product.ProductName = value; RaisePropertyChanged(() => ProductName); } } private ObservableCollection<TblProduct> _productRecords; public ObservableCollection<TblProduct> ProductRecords { get { return _productRecords; } set { _productRecords = value; RaisePropertyChanged("ProductRecords"); } } //Selected Product private TblProduct _selectedProduct; public TblProduct SelectedProduct { get { return _selectedProduct; } set { _selectedProduct = value; if (_selectedProduct != null) { this.ProductId = _selectedProduct.ProductId; this.ProductCode = _selectedProduct.ProductCode; } RaisePropertyChanged("SelectedProduct"); } } #endregion //Public Properties #endregion // Properties #region Commands private ICommand _newCommand; public ICommand NewCommand { get { if (_newCommand == null) { _newCommand = new RelayCommand(() => ResetAll()); } return _newCommand; } } private ICommand _saveCommand; public ICommand SaveCommand { get { if (_saveCommand == null) { _saveCommand = new RelayCommand(() => Save()); } return _saveCommand; } } private ICommand _deleteCommand; public ICommand DeleteCommand { get { if (_deleteCommand == null) { _deleteCommand = new RelayCommand(() => Delete()); } return _deleteCommand; } } #endregion //Commands #region Methods private void StartApp() { LoadProductCollection(); } private void LoadProductCollection() { var q = DataService.GetAllProducts(); this.ProductRecords = new ObservableCollection<TblProduct>(q); } private void Save() { if (SelectedOperateMode == OperateModeEnum.OperateMode.New) { //Pass the Model object into Dataservice for save DataService.SaveProduct(this.Product); } else if (SelectedOperateMode == OperateModeEnum.OperateMode.Edit) { //Pass the Model object into Dataservice for Update DataService.UpdateProduct(this.Product); } ResetAll(); LoadProductCollection(); } #endregion //Methods } Here is my Service class: class ProductDataService:IProductDataService { /// <summary> /// Context object of Entity Framework model /// </summary> private MaizeEntities Context { get; set; } public ProductDataService() { Context = new MaizeEntities(); } public IEnumerable<TblProduct> GetAllProducts() { using(var context=new R_MaizeEntities()) { var q = from p in context.TblProducts where p.IsDel == false select p; return new ObservableCollection<TblProduct>(q); } } public void SaveProduct(TblProduct _product) { using(var context=new R_MaizeEntities()) { _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.TblProducts.Add(_product); context.SaveChanges(); } } public void UpdateProduct(TblProduct _product) { using (var context = new R_MaizeEntities()) { context.TblProducts.Attach(_product); context.Entry(_product).State = EntityState.Modified; _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.SaveChanges(); } } public void DeleteProduct(int _productId) { using (var context = new R_MaizeEntities()) { var product = (from c in context.TblProducts where c.ProductId == _productId select c).First(); product.LastModUserId = GlobalObjects.LoggedUserID; product.LastModDttm = DateTime.Now; product.IsDel = true; context.SaveChanges(); } } } I exposed my model object in my viewModel by creating an instance of it using new keyword, also I instantiated my DataService class in VM. I know this will cause a strong dependency. So: What's the best way to expose a Model object in a ViewModel? What's the best way to use DataService in VM?

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  • MVVM- Expose Model object in ViewModel

    - by Angel
    I have a wpf MVVM application , I exposed my model object into my viewModel by creating an instance of Model class (which cause dependency) into ViewModel , and instead of creating seperate VM properties , I wrap the Model properties inside my ViewModel Property. My model is just an entity framework generated proxy classes. Here is my Model class : public partial class TblProduct { public TblProduct() { this.TblPurchaseDetails = new HashSet<TblPurchaseDetail>(); this.TblPurchaseOrderDetails = new HashSet<TblPurchaseOrderDetail>(); this.TblSalesInvoiceDetails = new HashSet<TblSalesInvoiceDetail>(); this.TblSalesOrderDetails = new HashSet<TblSalesOrderDetail>(); } public int ProductId { get; set; } public string ProductCode { get; set; } public string ProductName { get; set; } public int CategoryId { get; set; } public string Color { get; set; } public Nullable<decimal> PurchaseRate { get; set; } public Nullable<decimal> SalesRate { get; set; } public string ImagePath { get; set; } public bool IsActive { get; set; } public virtual TblCompany TblCompany { get; set; } public virtual TblProductCategory TblProductCategory { get; set; } public virtual TblUser TblUser { get; set; } public virtual ICollection<TblPurchaseDetail> TblPurchaseDetails { get; set; } public virtual ICollection<TblPurchaseOrderDetail> TblPurchaseOrderDetails { get; set; } public virtual ICollection<TblSalesInvoiceDetail> TblSalesInvoiceDetails { get; set; } public virtual ICollection<TblSalesOrderDetail> TblSalesOrderDetails { get; set; } } Here is my ViewModel , public class ProductViewModel : WorkspaceViewModel { #region Constructor public ProductViewModel() { StartApp(); } #endregion //Constructor #region Properties private IProductDataService _dataService; public IProductDataService DataService { get { if (_dataService == null) { if (IsInDesignMode) { _dataService = new ProductDataServiceMock(); } else { _dataService = new ProductDataService(); } } return _dataService; } } //Get and set Model object private TblProduct _product; public TblProduct Product { get { return _product ?? (_product = new TblProduct()); } set { _product = value; } } #region Public Properties public int ProductId { get { return Product.ProductId; } set { if (Product.ProductId == value) { return; } Product.ProductId = value; RaisePropertyChanged("ProductId"); } } public string ProductName { get { return Product.ProductName; } set { if (Product.ProductName == value) { return; } Product.ProductName = value; RaisePropertyChanged(() => ProductName); } } private ObservableCollection<TblProduct> _productRecords; public ObservableCollection<TblProduct> ProductRecords { get { return _productRecords; } set { _productRecords = value; RaisePropertyChanged("ProductRecords"); } } //Selected Product private TblProduct _selectedProduct; public TblProduct SelectedProduct { get { return _selectedProduct; } set { _selectedProduct = value; if (_selectedProduct != null) { this.ProductId = _selectedProduct.ProductId; this.ProductCode = _selectedProduct.ProductCode; } RaisePropertyChanged("SelectedProduct"); } } #endregion //Public Properties #endregion // Properties #region Commands private ICommand _newCommand; public ICommand NewCommand { get { if (_newCommand == null) { _newCommand = new RelayCommand(() => ResetAll()); } return _newCommand; } } private ICommand _saveCommand; public ICommand SaveCommand { get { if (_saveCommand == null) { _saveCommand = new RelayCommand(() => Save()); } return _saveCommand; } } private ICommand _deleteCommand; public ICommand DeleteCommand { get { if (_deleteCommand == null) { _deleteCommand = new RelayCommand(() => Delete()); } return _deleteCommand; } } #endregion //Commands #region Methods private void StartApp() { LoadProductCollection(); } private void LoadProductCollection() { var q = DataService.GetAllProducts(); this.ProductRecords = new ObservableCollection<TblProduct>(q); } private void Save() { if (SelectedOperateMode == OperateModeEnum.OperateMode.New) { //Pass the Model object into Dataservice for save DataService.SaveProduct(this.Product); } else if (SelectedOperateMode == OperateModeEnum.OperateMode.Edit) { //Pass the Model object into Dataservice for Update DataService.UpdateProduct(this.Product); } ResetAll(); LoadProductCollection(); } #endregion //Methods } Here is my Service class: class ProductDataService:IProductDataService { /// <summary> /// Context object of Entity Framework model /// </summary> private MaizeEntities Context { get; set; } public ProductDataService() { Context = new MaizeEntities(); } public IEnumerable<TblProduct> GetAllProducts() { using(var context=new R_MaizeEntities()) { var q = from p in context.TblProducts where p.IsDel == false select p; return new ObservableCollection<TblProduct>(q); } } public void SaveProduct(TblProduct _product) { using(var context=new R_MaizeEntities()) { _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.TblProducts.Add(_product); context.SaveChanges(); } } public void UpdateProduct(TblProduct _product) { using (var context = new R_MaizeEntities()) { context.TblProducts.Attach(_product); context.Entry(_product).State = EntityState.Modified; _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.SaveChanges(); } } public void DeleteProduct(int _productId) { using (var context = new R_MaizeEntities()) { var product = (from c in context.TblProducts where c.ProductId == _productId select c).First(); product.LastModUserId = GlobalObjects.LoggedUserID; product.LastModDttm = DateTime.Now; product.IsDel = true; context.SaveChanges(); } } } I exposed my model object in my viewModel by creating an instance of it using new keyword, also I instantiated my DataService class in VM, I know this will cause a strong dependency. So , 1- Whats the best way to expose Model object in ViewModel ? 2- Whats the best way to use DataService in VM ?

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  • MVVM Light V4 preview (BL0014) release notes

    - by Laurent Bugnion
    I just pushed to Codeplex an update to the MVVM Light source code. This is an early preview containing some of the features that I want to release later under the version 4. If you find these features useful for your project, please download the source code and build the assemblies. I will appreciate greatly any issue report. This version is labeled “V4.0.0.0/BL0014”. The “BL” string is an old habit that we used in my days at Siemens Building Technologies, called a “base level”. Somehow I like this way of incrementing the “base level” independently of any other consideration (such as alpha, beta, CTP, RTM etc) and continue to use it to tag my software versions. In Microsoft parlance, you could say that this is an early CTP of MVVM Light V4. Caveat The code is unit tested, but as we all know this does not mean that there are no bugs This code has not yet been used in production. Again, your help in testing this is greatly appreciated, so please report all bugs to me! What’s new? The following features have been implemented: Misc Various “maintenance work”. All WPF assemblies (that is .NET35 and .NET4) now allow partially trusted callers. It means that you can use them in am XBAP in partial trust mode. Testing Various test updates Added Windows Phone 7 unit tests Note: For Windows Phone 7, due to an issue in the unit test framework, not all tests can be executed. I had to isolate those tests for the moment. The error was reported to Microsoft. ViewModelBase The constructor is now public to allow serialization (especially useful on the phone to tombstone the state). ViewModelBase.MessengerInstance now returns Messenger.Default unless it is set explicitly. Previously, MessengerInstance was returning null, which was complicating the code. Two new ways to raise the PropertyChanged event have been added. See below for details. Messenger Updated the IMessenger interface with all public members from the Messenger class. Previously some members were missing. A new Unregister method is now available, allowing to unregister a recipient for a given token. RelayCommand RaiseCanExecuteChanged now acts the same in Windows Presentation Foundation than in Silverlight. In previous versions, I was relying on the CommandManager to raise the CanExecuteChanged event in WPF. However, it was found to be too unreliable, and a more direct way of raising the event was found preferable. See below for details. Raising the PropertyChanged event A very much requested update is now included: the ability to raise the PropertyChanged event in a viewmodel without using “magic strings”. Personally, I don’t see strings as a major issue, thanks to two features of the MVVM Light Toolkit: In the DEBUG configuration, every time that the RaisePropertyChanged method is called, the name of the property is checked against all existing properties of the viewmodel. Should the property name be misspelled (because of a typo or refactoring), an exception is thrown, notifying the developer that something is wrong. To avoid impacting the performance, this check is only made in DEBUG configuration, but that should be enough to warn the developers in case they miss a rename. The property name is defined as a public constant in the “mvvminpc” code snippet. This allows checking the property name from another class (for example if the PropertyChanged event is handled in the view). It also allows changing the property name in one place only. However, these two safeguards didn’t satisfy some of the users, who requested another way to raise the PropertyChanged event. In V4, you can now do the following: Using lambdas private int _myProperty; public int MyProperty { get { return _myProperty; } set { if (_myProperty == value) { return; } _myProperty = value; RaisePropertyChanged(() => MyProperty); } } This raises the property changed event using a lambda expression instead of the property name. Light reflection is used to get the name. This supports Intellisense and can easily be refactored. You can also broadcast a PropertyChangedMessage using the Messenger.Default instance with: private int _myProperty; public int MyProperty { get { return _myProperty; } set { if (_myProperty == value) { return; } var oldValue = _myProperty; _myProperty = value; RaisePropertyChanged(() => MyProperty, oldValue, value, true); } } Using no arguments When the RaisePropertyChanged method is called within a setter, you can also omit the property name altogether. This will fail if executed outside of the setter however. Also, to avoid confusion, there is no way to broadcast the PropertyChangedMessage using this syntax. private int _myProperty; public int MyProperty { get { return _myProperty; } set { if (_myProperty == value) { return; } _myProperty = value; RaisePropertyChanged(); } } The old way Of course the “old” way is still supported, without broadcast: public const string MyPropertyName = "MyProperty"; private int _myProperty; public int MyProperty { get { return _myProperty; } set { if (_myProperty == value) { return; } _myProperty = value; RaisePropertyChanged(MyPropertyName); } } And with broadcast: public const string MyPropertyName = "MyProperty"; private int _myProperty; public int MyProperty { get { return _myProperty; } set { if (_myProperty == value) { return; } var oldValue = _myProperty; _myProperty = value; RaisePropertyChanged(MyPropertyName, oldValue, value, true); } } Performance considerations It is notorious that using reflection takes more time than using a string constant to get the property name. However, after measuring for all platforms, I found the differences to be very small. I will measure more and submit the results to the community for evaluation, because some of the results are actually surprising (for example, using the Messenger to broadcast a PropertyChangedMessage does not significantly increase the time taken to raise the PropertyChanged event and update the bindings). For now, I submit this code to you, and would be delighted to hear about your own results. Raising the CanExecuteChanged event manually In WPF, until now, the CanExecuteChanged event for a RelayCommand was raised automatically. Or rather, it was attempted to be raised, using a feature that is only available in WPF called the CommandManager. This class monitors the UI and when something occurs, it queries the state of the CanExecute delegate for all the commands. However, this proved unreliable for the purpose of MVVM: Since very often the value of the CanExecute delegate changes according to non-UI events (for example something changing in the viewmodel or in the model), raising the CanExecuteChanged event manually is necessary. In Silverlight, the CommandManager does not exist, so we had to raise the event manually from the start. This proved more reliable, and I now changed the WPF implementation of the RaiseCanExecuteChanged method to be the exact same in WPF than in Silverlight. For instance, if a command must be enabled when a string property is set to a value other than null or empty string, you can do: public MainViewModel() { MyTestCommand = new RelayCommand( () => DoSomething(), () => !string.IsNullOrEmpty(MyProperty)); } public const string MyPropertyName = "MyProperty"; private string _myProperty = string.Empty; public string MyProperty { get { return _myProperty; } set { if (_myProperty == value) { return; } _myProperty = value; RaisePropertyChanged(MyPropertyName); MyTestCommand.RaiseCanExecuteChanged(); } } Logo update I made a minor change to the logo: Some people found the lack of the word “light” (as in MVVM Light Toolkit) confusing. I thought it was cool, because the feather suggests the idea of lightness, however I can see the point. So I added the word “light” to the logo. Things should be quite clear now. What’s next? This is only the first of a series of releases that will bring MVVM Light to V4. In the next weeks, I will continue to add some very requested features and correct some issues in the code. I will probably continue this fashion of releasing the changes to the public as source code through Codeplex. I would be very interested to hear what you think of that, and to get feedback about the changes. Cheers, Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • MVVM Light Toolkit - RelayCommands, DelegateCommands, and ObservableObjects

    - by DanM
    I just started experimenting with Laurent Bugnion's MVVM Light Toolkit. I think I'm going to really like it, but I have a couple questions. Before I get to them, I need to explain where I'm coming from. I currently use a combination of Josh Smith's MVVM Foundation and another project on Codeplex called MVVM Toolkit. I use ObservableObject and Messenger from MVVM Foundation and DelegateCommand and CommandReference from MVVM Toolkit. The only real overlap between MVVM Foundation and MVVM Tookit is that they both have an implementation for ICommand: MVVM Foundation has a RelayCommand and MVVM Tookit has a DelegateCommand. Of these two, DelegateCommand appears to be more sophisticated. It employs a CommandManagerHelper that uses weak references to avoid memory leaks. With that said, a couple questions: Why does MVVM Light Toolkit use RelayCommand rather than DelegateCommand? Is the use of weak references in an ICommand unnecessary or not recommended for some reason? Why is there no ObservableObject in MVVM Light? ObservableObject is basically just the part of ViewModelBase that implements INotifyPropertyChanged, but it's very convenient to have as a separate class because view-models are not the only objects that need to implement INotifyPropertyChanged. For example, let's say you have DataGrid that binds to a list of Person objects. If any of the properties in Person can change while the user is viewing the DataGrid, Person would need to implement INotifyPropertyChanged. (I realize that if Person is auto-generated using something like LinqToSql, it will probably already implement INotifyPropertyChanged, but there are cases where I need to make a view-specific version of entity model objects, say, because I need to include a command to support a button column in a DataGrid.) Thanks.

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  • How to tell which dataform button ended edit when using EventToCommand

    - by Rodd
    I'm new to SilverLight and Mvvm-Light. I have a DataForm on my view that displays/edits a SelectedPerson property (a Person object) of my view model. I want to execute a command on my viewmodel when the user clicks the Save button but don't want to take action if the user clicks cancel. I added the following to my ViewModel: public RelayCommand PersonEditEnded {get; set;} ... public void Initialize() { PersonEditEnded = new RelayCommand(DoSomething); ... } public void DoSomething() { } I added the following to my View: <toolkit:DataForm x:Name="PersonForm" ... CurrentItem="{Binding SelectedPerson, Mode=TwoWay}"> <i:Interaction.Triggers> <i:EventTrigger EventName="EditEnded"> <gs:EventToCommand Command="{Binding PersonEditEnded, Mode=OneWay}"/> </i:EventTrigger> </i:Interaction.Triggers> </toolkit:DataForm> This works and the DoSomething method is being called when the user presses Submit. However, DoSomething is also called when user presses Cancel. Is there a way to know which button was pressed or to supress the call when Cancel is pressed? Thanks for whatever help you can offer!

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  • WP7: Why does a ListBox.ItemsPanel break my ElementName data binding?

    - by iguanaNet
    I have a Windows Phone 7 ListBox that binds to a list of integers. I am using the default MVVM Light template, so there is a ViewModel class that contains data and a simple RelayCommand. Here is the ListBox: <ListBox ItemsSource="{Binding MyData}"> <ListBox.ItemTemplate> <DataTemplate> <Button Content="{Binding}"> <i:Interaction.Triggers> <i:EventTrigger EventName="Click"> <cmd:EventToCommand Command="{Binding ElementName=ContentGrid, Path=DataContext.TestCommand}" CommandParameter="{Binding}" /> </i:EventTrigger> </i:Interaction.Triggers> </Button> </DataTemplate> </ListBox.ItemTemplate> </ListBox> This displays a vertical list of integers inside buttons. If you click any of them, the following command code executes and shows a pop-up: new RelayCommand<int>(i => MessageBox.Show("Test" + i)); However, if I simply add the following XAML to change to a horizontal list, the databinding fails. Nothing happens when you click the button and no error messages are written to the Output window. <ListBox.ItemsPanel> <ItemsPanelTemplate> <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" /> </ItemsPanelTemplate> </ListBox.ItemsPanel> I have tried some other types of binding for the EventToCommand. For example, specifying my ViewModel as a static resource. It works, but is less ideal than the example above. Why does that ItemsPanel break the databinding?

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  • MVVM - implementing 'IsDirty' functionality to a ModelView in order to save data

    - by Brendan
    Hi, Being new to WPF & MVVM I struggling with some basic functionality. Let me first explain what I am after, and then attach some example code... I have a screen showing a list of users, and I display the details of the selected user on the right-hand side with editable textboxes. I then have a Save button which is DataBound, but I would only like this button to display when data has actually changed. ie - I need to check for "dirty data". I have a fully MVVM example in which I have a Model called User: namespace Test.Model { class User { public string UserName { get; set; } public string Surname { get; set; } public string Firstname { get; set; } } } Then, the ViewModel looks like this: using System.Collections.ObjectModel; using System.Collections.Specialized; using System.Windows.Input; using Test.Model; namespace Test.ViewModel { class UserViewModel : ViewModelBase { //Private variables private ObservableCollection<User> _users; RelayCommand _userSave; //Properties public ObservableCollection<User> User { get { if (_users == null) { _users = new ObservableCollection<User>(); //I assume I need this Handler, but I am stuggling to implement it successfully //_users.CollectionChanged += HandleChange; //Populate with users _users.Add(new User {UserName = "Bob", Firstname="Bob", Surname="Smith"}); _users.Add(new User {UserName = "Smob", Firstname="John", Surname="Davy"}); } return _users; } } //Not sure what to do with this?!?! //private void HandleChange(object sender, NotifyCollectionChangedEventArgs e) //{ // if (e.Action == NotifyCollectionChangedAction.Remove) // { // foreach (TestViewModel item in e.NewItems) // { // //Removed items // } // } // else if (e.Action == NotifyCollectionChangedAction.Add) // { // foreach (TestViewModel item in e.NewItems) // { // //Added items // } // } //} //Commands public ICommand UserSave { get { if (_userSave == null) { _userSave = new RelayCommand(param => this.UserSaveExecute(), param => this.UserSaveCanExecute); } return _userSave; } } void UserSaveExecute() { //Here I will call my DataAccess to actually save the data } bool UserSaveCanExecute { get { //This is where I would like to know whether the currently selected item has been edited and is thus "dirty" return false; } } //constructor public UserViewModel() { } } } The "RelayCommand" is just a simple wrapper class, as is the "ViewModelBase". (I'll attach the latter though just for clarity) using System; using System.ComponentModel; namespace Test.ViewModel { public abstract class ViewModelBase : INotifyPropertyChanged, IDisposable { protected ViewModelBase() { } public event PropertyChangedEventHandler PropertyChanged; protected virtual void OnPropertyChanged(string propertyName) { PropertyChangedEventHandler handler = this.PropertyChanged; if (handler != null) { var e = new PropertyChangedEventArgs(propertyName); handler(this, e); } } public void Dispose() { this.OnDispose(); } protected virtual void OnDispose() { } } } Finally - the XAML <Window x:Class="Test.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:vm="clr-namespace:Test.ViewModel" Title="MainWindow" Height="350" Width="525"> <Window.DataContext> <vm:UserViewModel/> </Window.DataContext> <Grid> <ListBox Height="238" HorizontalAlignment="Left" Margin="12,12,0,0" Name="listBox1" VerticalAlignment="Top" Width="197" ItemsSource="{Binding Path=User}" IsSynchronizedWithCurrentItem="True"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel> <TextBlock Text="{Binding Path=Firstname}"/> <TextBlock Text="{Binding Path=Surname}"/> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> <Label Content="Username" Height="28" HorizontalAlignment="Left" Margin="232,16,0,0" Name="label1" VerticalAlignment="Top" /> <TextBox Height="23" HorizontalAlignment="Left" Margin="323,21,0,0" Name="textBox1" VerticalAlignment="Top" Width="120" Text="{Binding Path=User/UserName}" /> <Label Content="Surname" Height="28" HorizontalAlignment="Left" Margin="232,50,0,0" Name="label2" VerticalAlignment="Top" /> <TextBox Height="23" HorizontalAlignment="Left" Margin="323,52,0,0" Name="textBox2" VerticalAlignment="Top" Width="120" Text="{Binding Path=User/Surname}" /> <Label Content="Firstname" Height="28" HorizontalAlignment="Left" Margin="232,84,0,0" Name="label3" VerticalAlignment="Top" /> <TextBox Height="23" HorizontalAlignment="Left" Margin="323,86,0,0" Name="textBox3" VerticalAlignment="Top" Width="120" Text="{Binding Path=User/Firstname}" /> <Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="368,159,0,0" Name="button1" VerticalAlignment="Top" Width="75" Command="{Binding Path=UserSave}" /> </Grid> </Window> So basically, when I edit a surname, the Save button should be enabled; and if I undo my edit - well then it should be Disabled again as nothing has changed. I have seen this in many examples, but have not yet found out how to do it. Any help would be much appreciated! Brendan

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  • WPF Binding KeyDown event to Command

    - by Daniil Harik
    Hello, I want to bind KeyDown event handler (when user presses Ctrl+C and Ctrl+V) on Telerik's GridView to RelayCommand object in my ViewModel. I know about this post http://blog.functionalfun.net/2008/09/hooking-up-commands-to-events-in-wpf.html But I'm still bit confused about implementation of my scenario. I just don't understand how it works. Could someone point out how should my scenario be implemented. Thank You very much!

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  • Silverlight 4 + MVVM + KeyDown event

    - by jturn
    I'm trying to build a sample game in Silverlight 4 using the MVVM design pattern to broaden my knowledge. I'm using Laurent Bugnion's MvvmLight toolkit as well (found here: http://mvvmlight.codeplex.com/ ). All I want to do right now is move a shape around within a Canvas by pressing specific keys. My solution contains a Player.xaml (just a rectangle; this will be moved around) and MainPage.xaml (the Canvas and an instance of the Player control). To my understanding, Silverlight doesn't support tunneling routed events, only bubbling. My big problem is that Player.xaml never recognizes the KeyDown event. It's always intercepted by MainPage.xaml first and it never reaches any child controls because it bubbles upward. I'd prefer that the logic to move the Player be in the PlayerViewModel class, but I don't think the Player can know about any KeyDown events firing without me explicitly passing them on down from the MainPage. I ended up adding the handler logic to the MainPageViewModel class. Now my problem is that the MainPageViewModel has no knowledge of Player.xaml so it cannot move this object when handling KeyDown events. I guess this is expected, as ViewModels should not have any knowledge of their associated Views. In not so many words...is there a way this Player user control within my MainPage.xaml can directly accept and handle KeyDown events? If not, what's the ideal method for my MainPageViewModel to communicate with its View's child controls? I'm trying to keep code out of the code-behind files as much as possible. Seems like it's best to put logic in the ViewModels for ease of testing and to decouple UI from logic. (MainPage.xaml) <UserControl x:Class="MvvmSampleGame.MainPage" 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" xmlns:game="clr-namespace:MvvmSampleGame" xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" xmlns:cmd="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Extras.SL4" mc:Ignorable="d" Height="300" Width="300" DataContext="{Binding Main, Source={StaticResource Locator}}"> <i:Interaction.Triggers> <i:EventTrigger EventName="KeyDown"> <cmd:EventToCommand Command="{Binding KeyPressCommand}" PassEventArgsToCommand="True" /> </i:EventTrigger> </i:Interaction.Triggers> <Canvas x:Name="LayoutRoot"> <game:Player x:Name="Player1"></game:Player> </Canvas> (MainViewModel.cs) public MainViewModel() { KeyPressCommand = new RelayCommand<KeyEventArgs>(KeyPressed); } public RelayCommand<KeyEventArgs> KeyPressCommand { get; private set; } private void KeyPressed(KeyEventArgs e) { if (e.Key == Key.Up || e.Key == Key.W) { // move player up } else if (e.Key == Key.Left || e.Key == Key.A) { // move player left } else if (e.Key == Key.Down || e.Key == Key.S) { // move player down } else if (e.Key == Key.Right || e.Key == Key.D) { // move player right } } Thanks in advance, Jeremy

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  • How do you mock ViewModel Commands using moq?

    - by devnet247
    Hi I might be approaching this all wrong.But please help me to understand. I really want to TDD building wpf application using Moq. I would like to mock the viewmodel. Application Show a list of contacts and when you double click on a contact it shows the contact. Test Moq GetContactsCommand.Test it has been called. Test that you get a list of contacts. Not sure how to mock the viewModel and it's commands can you correct me? So I have started to do the following [Test] public void Should_be_able_to_mock_getContactsCommand_and_get_a_list_of_contacts() { //Arrange var expectedContacts = new ObservableCollection<ContactViewModel> { new ContactViewModel(new ContactModel { FirstName = "Jo", LastName = "Bloggs", Email = "[email protected]" }), new ContactViewModel(new ContactModel { FirstName = "Mary", LastName = "Bloggs", Email = "[email protected]" }) }; var mock = new Mock<IContactListViewModel>(); mock.SetupGet(x => x.GetContactsCommand).Verifiable(); mock.SetupGet(x => x.Contacts).Returns(expectedContacts); //Act //? //assert mock.VerifySet(x => x.Contacts, Times.AtLeastOnce()); mock.Object.Contacts.Count.ShouldEqual(expectedContacts.Count); } public interface IContactListViewModel { ObservableCollection<ContactViewModel> Contacts { get; set; } ICommand GetContactsCommand{ get; } } public interface IContactModel { string FirstName { get; set; } string LastName { get; set; } string Email { get; set; } } public class ContactModel : IContactModel { public string FirstName { get; set; } public string LastName { get; set; } public string Email { get; set; } } public class ContactViewModel : ViewModelBase { private readonly ContactModel _contactModel; public ContactViewModel(ContactModel contactModel) { _contactModel = contactModel; } public string FirstName { get { return _contactModel.FirstName; } set { _contactModel.FirstName = value; OnPropertyChanged("FirstName"); } } public string LastName { get { return _contactModel.LastName; } set { _contactModel.LastName = value; OnPropertyChanged("LastName"); } } public string Email { get { return _contactModel.Emai; } set { _contactModel.Email = value; OnPropertyChanged("Email"); } } } public class ContactListViewModel : ViewModelBase, IContactListViewModel { private ObservableCollection<ContactViewModel> _contacts; public ObservableCollection<ContactViewModel> Contacts { get { return _contacts; } set { _contacts = value; OnPropertyChanged("Contacts"); } } private RelayCommand _getContactsCommand; public ICommand GetContactsCommand { get { return _getContactsCommand ?? (_getContactsCommand = new RelayCommand(x => GetContacts(), x => CanGetContacts)); } } private static bool CanGetContacts { get { return true; } } private void GetContacts() { //pretend we are going to the service or db whatever Contacts = new ObservableCollection<ContactViewModel> { new ContactViewModel(new ContactModel { FirstName = "Jo", LastName = "Bloggs", Email = "[email protected]" }), new ContactViewModel(new ContactModel { FirstName = "Mary", LastName = "Bloggs", Email = "[email protected]" }) }; } }

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  • MVVM, ContextMenus and binding to ViewModel defined Command

    - by Simon Fox
    Hi I am having problems with the binding of a ContextMenu command to an ICommand property in my ViewModel. The binding seems to be attaching fine...i.e when I inspect the value of the ICommand property it is bound to an instance of RelayCommand. The CanExecute delegate does get invoked, however when I open the context menu and select an item the Execute delegate does not get invoked. Heres my View (which is defined as the DataTemplate to use for instances of the following ViewModel in a resource dictionary): <UserControl x:Class="SmartSystems.DragDropProto.ProductLinkView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:Proto"> <UserControl.Resources> <local:CenteringConverter x:Key="centeringConvertor"> </local:CenteringConverter> </UserControl.Resources> <UserControl.ContextMenu> <ContextMenu> <MenuItem Command="{Binding ChangeColor}">Change Color</MenuItem> </ContextMenu> </UserControl.ContextMenu> <Canvas> <Ellipse Width="5" Height="5" > <Ellipse.Fill> <SolidColorBrush Color="{Binding LinkColor}"></SolidColorBrush> </Ellipse.Fill> <Ellipse.RenderTransform> <TranslateTransform X="{Binding EndpointOneXPos, Converter={StaticResource centeringConvertor}}" Y="{Binding EndpointOneYPos, Converter={StaticResource centeringConvertor}}"/> </Ellipse.RenderTransform> </Ellipse> <Line X1="{Binding Path=EndpointOneXPos}" Y1="{Binding Path=EndpointOneYPos}" X2="{Binding Path=EndpointTwoXPos}" Y2="{Binding Path=EndpointTwoYPos}"> <Line.Stroke> <SolidColorBrush Color="{Binding LinkColor}"></SolidColorBrush> </Line.Stroke> </Line> <Ellipse Width="5" Height="5" > <Ellipse.Fill> <SolidColorBrush Color="{Binding LinkColor}"></SolidColorBrush> </Ellipse.Fill> <Ellipse.RenderTransform> <TranslateTransform X="{Binding EndpointTwoXPos, Converter={StaticResource centeringConvertor}}" Y="{Binding EndpointTwoYPos, Converter={StaticResource centeringConvertor}}"/> </Ellipse.RenderTransform> </Ellipse> </Canvas> </UserControl> and ViewModel (with uneccessary implementation details removed): class ProductLinkViewModel : BaseViewModel { public ICommand ChangeColor { get; private set; } public Color LinkColor { get; private set; } public ProductLinkViewModel(....) { ... ChangeColor = new RelayCommand(ChangeColorAction); LinkColor = Colors.Blue; } private void ChangeColorAction(object param) { LinkColor = LinkColor == Colors.Blue ? Colors.Red : Colors.Blue; OnPropertyChanged("LinkColor"); } }

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  • Distinguishing between UI command & domain commands

    - by SonOfPirate
    I am building a WPF client application using the MVVM pattern that provides an interface on top of an existing set of business logic residing in a library which is shared with other applications. The business library followed a domain-driven architecture using CQRS to separate the read and write models (no event sourcing). The combination of technologies and patterns has brought up an interesting conundrum: The MVVM pattern uses the command pattern for handling user-interaction with the view models. .NET provides an ICommand interface which is implemented by most MVVM frameworks, like MVVM Light's RelayCommand and Prism's DelegateCommand. For example, the view model would expose a number of command objects as properties that are bound to the UI and respond when the user performs actions like clicking buttons. Many implementations of the CQRS use the command pattern to isolate and encapsulate individual behaviors. In my business library, we have implemented the write model as command / command-handler pairs. As such, when we want to do some work, such as create a new order, we 'issue' a command (CreateOrderCommand) which is routed to the command-handler responsible for executing the command. This is great, clearly explained in many sources and I am good with it. However, take this scenario: I have a ToolbarViewModel which exposes a CreateNewOrderCommand property. This ICommand object is bound to a button in the UI. When clicked, the UI command creates and issues a new CreateOrderCommand object to the domain which is handled by the CreateOrderCommandHandler. This is difficult to explain to other developers and I am finding myself getting tongue-tied because everything is a command. I'm sure I'm not the first developer to have patterns overlap like this where the naming/terminology also overlap. How have you approached distinguishing your commands used in the UI from those used in the domain? (Edit: I should mention that the business library is UI-agnostic, i.e. no UI technology-specific code exists, or will exists, in this library.)

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  • MVVM- Trigger Storyboard in the View Model in Silverlight

    - by user275561
    I have a couple of Storyboards in my view that I would like to trigger from the ViewModel if possible. Is there a simple way or elegant way of doing this. Here is what I am trying to do. Person Clicks on a Button--RelayCommand (In the ViewModel), the Relay Command should then play the storyboard. Also one more thing, I would like to also trigger the storyboard animation by itself in the ViewModel without any interaction. <i:Interaction.Triggers> <i:EventTrigger EventName="MouseLeftButtonDown"> <cmd:EventToCommand Command="{Binding ButtonPress}" CommandParameterValue="RedButtonLight"> </cmd:EventToCommand> </i:EventTrigger> </i:Interaction.Triggers>

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  • Casting in MVVM Light CommandParameterValue

    - by user275561
    here is my Problem, I want to pass the integer 1 when this canvas is pressed. Every time I click the canvas, I get a An unhandled exception of type 'System.InvalidCastException' occurred in GalaSoft.MvvmLight.dll. Now I could make my life easier and just do the RelayCommand to accept a String instead of int but for the sake of learning. How would i go about doing it this way, <i:Interaction.Triggers> <i:EventTrigger EventName="MouseLeftButtonDown"> <cmd:EventToCommand Command="{Binding ButtonPress}" CommandParameterValue="1" </i:EventTrigger> </i:Interaction.Triggers>

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  • Casting in MVVM Light CommandParamterValue

    - by user275561
    here is my Problem, I want to pass the integer 1 when this canvas is pressed. Every time I click the canvas, I get a An unhandled exception of type 'System.InvalidCastException' occurred in GalaSoft.MvvmLight.dll. Now I could make my life easier and just do the RelayCommand to accept a String instead of int but for the sake of learning. How would i go about doing it this way, <i:Interaction.Triggers> <i:EventTrigger EventName="MouseLeftButtonDown"> <cmd:EventToCommand Command="{Binding ButtonPress}" CommandParameterValue="1" </i:EventTrigger> </i:Interaction.Triggers>

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  • Bound Command not firing on another viewModel? What Am I doing wrong?

    - by devnet247
    Hi I cannot seem to bind a command to a button.I have a treeview on the left showing Country City etc.. And I tabcontrol on the right. do I This uses 4 viewModels rootviewModel-ContinentViewModel-CountryViewModel-CityViewModel What I am building is based on http://www.codeproject.com/KB/WPF/TreeViewWithViewModel.aspx Now on one of the tabs I have a Toolbar with a button "TestButton" that I have mapped in zaml. This does not fire! The reason is not firing is because I m binding the RootViewModel but the command that is bound in zaml is in the cityViewModel. How Do I pass the datacontext from one view to the other? or how do I make the button fire. I need the command to be in the cityViewModel. Any Suggestions on how I bind it? View "WorldExplorerView" where I bind the main DataContext public partial class WorldExplorerView { public WorldExplorerView() { InitializeComponent(); var continents = Database.GetContinents(); var rootViewModel = new RootViewModel(continents); DataContext = rootViewModel; } } CityViewModel public class CityViewModel : TreeViewItemViewModel { private City _city; private RelayCommand _testCommand; public CityViewModel(City city, CountryViewModel countryViewModel):base(countryViewModel,false) { _city = city; } Properties etc...... public ICommand TestCommand { get { if(_testCommand==null) { _testCommand = new RelayCommand(param => GetTestCommand(), param => CanCallTestCommand); ; } return _testCommand; } } protected bool CanCallTestCommand { get { return true; } } private static void GetTestCommand() { MessageBox.Show("It works"); } } ZAML <DockPanel> <DockPanel LastChildFill="True"> <Label DockPanel.Dock="top" Content="Title " HorizontalAlignment="Center"></Label> <StatusBar DockPanel.Dock="Bottom"> <StatusBarItem Content="Status Bar" ></StatusBarItem> </StatusBar> <Grid DockPanel.Dock="Top"> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition Width="Auto"/> <ColumnDefinition Width="2*"/> </Grid.ColumnDefinitions> <TreeView Name="tree" ItemsSource="{Binding Continents}"> <TreeView.ItemContainerStyle> <Style TargetType="{x:Type TreeViewItem}"> <Setter Property="IsExpanded" Value="{Binding IsExpanded,Mode=TwoWay}"/> <Setter Property="IsSelected" Value="{Binding IsSelected,Mode=TwoWay}"/> <Setter Property="FontWeight" Value="Normal"/> <Style.Triggers> <Trigger Property="IsSelected" Value="True"> <Setter Property="FontWeight" Value="Bold"></Setter> </Trigger> </Style.Triggers> </Style> </TreeView.ItemContainerStyle> <TreeView.Resources> <HierarchicalDataTemplate DataType="{x:Type ViewModels:ContinentViewModel}" ItemsSource="{Binding Children}"> <StackPanel Orientation="Horizontal"> <Image Width="16" Height="16" Margin="3,0" Source="Images\Continent.png"/> <TextBlock Text="{Binding ContinentName}"/> </StackPanel> </HierarchicalDataTemplate> <HierarchicalDataTemplate DataType="{x:Type ViewModels:CountryViewModel}" ItemsSource="{Binding Children}"> <StackPanel Orientation="Horizontal"> <Image Width="16" Height="16" Margin="3,0" Source="Images\Country.png"/> <TextBlock Text="{Binding CountryName}"/> </StackPanel> </HierarchicalDataTemplate> <DataTemplate DataType="{x:Type ViewModels:CityViewModel}" > <StackPanel Orientation="Horizontal"> <Image Width="16" Height="16" Margin="3,0" Source="Images\City.png"/> <TextBlock Text="{Binding CityName}"/> </StackPanel> </DataTemplate> </TreeView.Resources> </TreeView> <GridSplitter Grid.Row="0" Grid.Column="1" Background="LightGray" Width="5" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/> <Grid Grid.Column="2" Margin="5" > <TabControl> <TabItem Header="Demo"> <DockPanel LastChildFill="True"> <ToolBar DockPanel.Dock="Top"> <!-- DOES NOT WORK--> <Button Name="btnTest" Command="{Binding TestCommand}" Content="Press me see if works"></Button> </ToolBar> <TextBox></TextBox> </DockPanel> </TabItem> <TabItem Header="Details" DataContext="{Binding Path=SelectedItem.City, ElementName=tree, Mode=OneWay}"> <StackPanel > <TextBlock VerticalAlignment="Center" FontSize="12" Text="{Binding CityName}"/> <TextBlock VerticalAlignment="Center" FontSize="12" Text="{Binding Area}"/> <TextBlock VerticalAlignment="Center" FontSize="12" Text="{Binding Population}"/> <TextBlock VerticalAlignment="Center" FontSize="12" Text="{Binding CityDetailsInfo.ClubsCount}"/> <TextBlock VerticalAlignment="Center" FontSize="12" Text="{Binding CityDetailsInfo.PubsCount}"/> </StackPanel> </TabItem> </TabControl> </Grid> </Grid> </DockPanel> </DockPanel>

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  • MVVM (ICommand) in Silverlight

    - by Andrey Khataev
    Hello! Please, don't judge strictly if this question was discussed previously or indirectly answered in huge nearby prism and mvvm blogs. In WPF implementation of RelayCommand or DelegateCommand classes there is a such eventhandler /// <summary> /// Occurs whenever the state of the application changes such that the result of a call to <see cref="CanExecute"/> may return a different value. /// </summary> public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager.RequerySuggested -= value; } } but in SL subset of namespaces there are no CommandManager class. And this is where I'm stuck. I haven't yet found an workaround for this in MVVM adoptation for SL (PRISM is so complex for me yet). Different simple HelloWorldMVVM apps don't deal with at all. Thanks in advance and sorry for my English -)

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  • MVVM Light is too fast :)

    - by Hikari
    Hello, I have a simple WM7 Page with textbox. Futher, I assigned EventToCommand (RelayCommand) to this textbox, reacting to TextChanged event. For testing pourposes I made additional method TextBox_TextChanged in page's code behing. Both command and TextBox_TextChanged print a message box with the textbox content. Initial value of textbox is ABC. Then I press D and: 1) TextBox_TextChanged prints ABCD. 2) Command prints ABC. D is missing. Why commands is so fast???

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  • ICOmmand - canexecute can not disable Button with image content.

    - by Anish
    Hi , I have a button control in my wpf-mvvm application. I use an ICommand property (defined in viewmodel) to bind the button click event to viewmodel. I have - execute and canexecute parameters for my ICommand implementation (RelayCommand). Even if CanExecute is false...button is not disabled...WHEN button CONTENT is IMAGE But, when button content is text..enable/disable works fine. <Button DockPanel.Dock="Top" Command="{Binding Path=MoveUpCommand}"> <Button.Content> <Image Source="/Resources/MoveUpArrow.png"></Image> </Button.Content> <Style> <Style.Triggers> <Trigger Property="IsEnabled" Value="False"> <Setter Property="Opacity" Value=".5" /> </Trigger> </Style.Triggers> </Style> </Button>

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  • CommandManager "cannot resolve symbol"

    - by Budda
    After adding "RelayCommand" class (that uses CommandManager class) into my Silverlight App I've got an error: The name 'CommandManager' does not exist in the current context This class is a member of System.Windows.Input namespace that is in PresentationCore.dll assembly. The problem is that I can't add this dll into my app... I am having a strange assumption: this class (CommmandManager) can't be used in the Silverlight. Am I right? How can I implement MVVM-pattern (http://msdn.microsoft.com/en-us/magazine/dd419663.aspx)? Thanks.

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