.NET 3.5

Bug fix: WPF4 project template for #MVVMLight V3

Laurent Bugnion — Tue, 24 Jan 2012 23:40:09 GMT

Ironically, my last release of MVVM Light V3 was about fixing bugs in templates and making them better. In the process however, seems that I introduced a regression bug in the WPF4 project templates. Yep shit happens.

How do I know if I have the bug?

Check the Programs and Features control panel, and look for MVVM Light. If the “Version” column shows 3.0.2.19, you have the bug. If it shows anything higher, you don’t. For instance, the new version with the bug correction is 3.0.3.19. Also, any version 4.*.*.* does not have this bug.

Alternatively, simply try to create a new WPF4 MVVM Light application in Studio. If you see the following warning, you have the bug.

Upgrading

To fix the bug, simply download V3.0.3.19 from Codeplex and install. You don’t need to uninstall the previous version.

What’s next?

I am working hard on V4 and have some nice improvements coming up. Many people have asked me when the “beta” will come out of MVVM Light, and the answer is “soon”. In the coming few days, I will publish a temporary release that corrects a few memory leaks, notably in the Messenger and in the RelayCommand. This will give expert users time to test and report issues. Then I still have a couple of fixes and I will release a release candidate. I won’t add any new feature after the RC, but will merely fix bugs if people find some. Once the RC is deemed stable, I will release V4 and take a deep breath!

And yes, there will be a V5

Happy coding,
Laurent

Laurent Bugnion (GalaSoft)
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New MVVM Light templates with bug fixes

Laurent Bugnion — Mon, 02 Jan 2012 20:13:28 GMT

The current version of MVVM Light had a couple of issues in the project templates. The most annoying one was causing a problem when creating new projects: The GUIDs used to uniquely identify the project were in fact not re-generated properly every time, and we ended up with the same GUID in every new project. The symptoms are the following: If you side-load an MVVM Light application, and then side-load another one, you will see that the first one is overwritten. Note however that this is only an issue when side-loading applications: The GUIDs are properly re-generated and overwritten by Microsoft during the app approval process.

This was not really an issue with WPF and Silverlight applications (which is why the bug was never found until now), however the Windows Phone uses these GUIDs to check if the application is already installed on the Windows Phone device or not.

I also took this occasion to update the templates with some information in the AssemblyInfo.cs, so that should make it even easier to fill the assembly information.

I just published a new MSI that corrects the issue. You can install the new MSI on top of the existing one. As usual, there is an MSI for MVVM Light V3 and one for MVVM Light V4 beta.

Fixing the issue in existing applications

If you encounter this issue in existing application, you can use the following steps to correct it. Note that I recommend you to follow these steps for every MVVM Light application.

Start the GUID generator installed with Visual Studio (open the Start menu and type GUID to find it).
In the GUID generator, select the Registry Format.
Press the New GUID button and then the Copy button.

Open the CSPROJ file in Notepad (or any text editor).
Locate the <ProjectGuid> attribute.
Select its content and paste the GUID you previously copied.

For Windows Phone projects only, in addition:

In the GUID generator, press the New GUID button and then the Copy button.
Open the file WMAppManifest.xml (in the Properties folder).
Find the ProductID attribute and replace its content with the GUID you previously copied.

Projects exposed to COM

Some project also have a GUID in the AssemblyInfo.cs. Open this file in Visual Studio or in Notepad and check if you can see a GUID there. If there is one, copy a new GUID from the GUID generator and replace the old one with the one you just copied. Be careful to remove the opening ‘{‘ and closing ‘}’.

That’s it

Apologies for this bug, and thanks to everyone who reported it and helped make MVVM Light better.

Cheers,
Laurent

Laurent Bugnion (GalaSoft)
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MVVM Light installers and Nuget (including Silverlight 5) #mvvmlight

Laurent Bugnion — Sun, 18 Dec 2011 21:10:12 GMT

I just pushed two big updates to MVVM Light setup components.

MSI installers with Silverlight 5 support

The MSI installers are available on Codeplex. The current version supports Silverlight 3, Silverlight 4, Silverlight 5 (new), WPF 3.5 SP1, WPF 4, Windows Phone 7.0 and Windows Phone 7.1. The installer for V3 is available, as well as the one for V4 beta.

NuGet support including Silverlight 5

I also pushed a new version of the NuGet packages which includes Silverlight 5. To install MVVM Light into an existing application with the help of the NuGet package manager in Visual Studio, check the instructions.

If you look for “mvvmlight” on NuGet, you will find four packages:

MVVM Light: The whole package, libraries + ViewModelLocator + MainViewModel. Installing this also modifies App.xaml to install the ViewModelLocator. This package is for V3 of MVVM Light!
MVVM Light libraries only: Installs only the DLLs and references them. This package is for V3 of MVVM Light!
MVVM Light [Preview]: This is the whole package too, but for V4 beta.
MVVM Light libraries only [Preview]: Just the DLLs, for V4 beta.

Update on V4’s availability

One of the most annoying issues in V3 is a memory leak that can appear in the Messenger component in certain circumstances. I will post details in due time, but there is indeed a risk that an instance is not garbage collected if it is registered with the Messenger with a non-static method, and if the developer omits to unregister the instance before deleting it.

Because of the promise of a “weak” registration, I really want to solve this issue. Currently, I am able to completely solve it in WPF, and to solve it in most cases in Silverlight (including Windows Phone). There is still one special case in Silverlight where a memory leak may remain, and I am currently working on handling this. I am not sure that there is a solution for this last scenario, but there are other alternatives that it is not a blocking issue anymore.

Once this fix is fully tested, I still have a few things I would like to add in V4. However I am also aware that we have been in beta (and alpha) for quite some time already, and it is very possible that I procrastinate some of these features into V5.

Happy coding!
Laurent

Laurent Bugnion (GalaSoft)
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MVVM Light V4 beta1

Laurent Bugnion — Mon, 12 Sep 2011 16:00:20 GMT

This morning, I published MVVM Light V4 beta1 in the form of an MSI. The installation instructions are detailed on the MVVM Light installation page. Please make sure to uninstall previous versions before you install V4 beta1.

There are quite a few changes in this version, and I plan to blog about various features in the coming days. As usual, stay tuned!

Change log

General changes

Added XmlnsDefinitionAttribute for GalaSoft.MvvmLight.Command in Extras assembly.

Setup

Created an installer.

Messenger

Fixed Issue #7521: race condition in Messenger.Default.
Fixed Issue #7539: Messenger support for uncast objects.

ViewModelBase

Added support for RaisePropertyChanged(null) and RaisePropertyChanged(string.empty). A blog post about this will follow.
Fixed Issue #7520: RaisePropertyChanged() fails in ReleaseBuild. This overload was removed because of the many issues, and replaced by the Set methods.
Added Set(...) methods. A blog post about this will follow.

RelayCommand

Fixed Issue #7522: used deprecated Predicate instead of Func.
Fixed Issue #7534: RelayCommand has security issue.

SimpleIoc

Implemented method IsRegistered<T>(). A blog post about this will follow.
Fixed issue "Contains<T>() is returning true even if no instance was already instantiated". Contains<T>() only returns true if an instance is already created. IsRegistered<T>() returns true if the class has been registered with the IOC container.
Fixed issue "Instances get created at registration already when registered with a key and a factory". Registering the instance does not execute the factory method yet. The method is only executed when the method GetInstance is called the first time.
Fixed issue "Use the correct DLLs for CommonServiceLocator". The original DLLs from http://commonservicelocator.codeplex.com are now used everywhere.

DispatcherHelper

The class was moved from GalaSoft.MvvmLight.Extras.dll into GalaSoft.MvvmLight.dll.

Project Templates

A couple of internal changes to the template's structure.
Using the new slightly modified MVVM Light logo.

ViewModelLocator Template

Modified template to use SimpleIoc.
A couple of internal changes to the template's structure.
Using the new slightly modified MVVM Light logo.

ViewModel Template

A couple of internal changes to the template's structure.
Using the new slightly modified MVVM Light logo.

View Template

Fixed issue in XAML for WP7 and WP7.1 templates.
A couple of internal changes to the template's structure.
Using the new slightly modified MVVM Light logo.

INPC snippet

Setter in property is now public.
Added $end$ marker.
Added new snippets with various ways to call RaisePropertyChanged.
Added a snippet using the new ViewModelBase.Set() method.
A blog post will follow about all this.

ViewModelLocator property snippet

Added $end$ marker.
Modified to use SimpleIoc.

Relay Command snippets

Added code snippets for RelayCommands. A blog post about this will follow.

Details

XmlnsDefinitionAttribute for GalaSoft.MvvmLight.Command in Extras assembly

Thanks to the addition of XmlnsDefinitionAttribute, you can simplify the inclusion of the MVVM Light EventToCommand action in XAML. See the before and after below:

Before:

<UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity" 
             
             xmlns:cmd="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Extras.SL4"
             
             xmlns:cmd="http://www.galasoft.ch/mvvmlight" 
             x:Class="MvvmLight4.MainPage">

After:

<UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity" 
             xmlns:cmd="http://www.galasoft.ch/mvvmlight" 
             x:Class="MvvmLight4.MainPage">

Laurent Bugnion (GalaSoft)
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MVVM light V3 installer for non-English systems

Laurent Bugnion — Thu, 01 Sep 2011 20:28:01 GMT

After I released the MVVM Light installer, I got a note saying that parts of the installation failed on non-English systems (in that case a German installation of Expression Blend and Visual Studio). Specifically, what failed was the code snippets on Visual Studio, and the project and item templates in Expression Blend.

After investigating, it is correct that these two particular features of MVVM Light were installed to language-coded folders. Correcting the issue for Expression Blend was easy enough (Blend can also find project and item templates in the My Documents folder, under Expression\Blend 4\ItemTemplates and Expression\Blend 4\ProjectTemplates, which are language independent).

Unfortunately it was not that easy for code snippets, so eventually I had to resort to a few custom actions in the installer. How annoying that we cannot install code snippets to a language-neutral folder!!

Anyway, after a lot of efforts and even more testing, I published a new version which corrects the previous issues. So now I can happily resume my efforts on V4 beta 1 which is nearing completion, and which will also come with a neat installer

Happy coding,

Laurent

Laurent Bugnion (GalaSoft)
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Automated installer for MVVM Light V3!

Laurent Bugnion — Sat, 06 Aug 2011 23:50:59 GMT

For a very (too) long time, the installation procedure for MVVM Light sucked. It involved downloading and unzipping files in various locations. Unfortunately, creating an automated installer is not completely trivial because of the variety of files that are getting installed: Binaries, Code Snippets, Project and Item Templates, all require different locations, and all that for VS2008, VS2010, Blend 4 and Silverlight 3, Silverlight 4, WPF3.5 SP1, WPF4, WP7.0 and now WP7.1 “Mango”.

Thankfully, MVVM Light is taking advantage of a great community. First, Leon Zandman initiated the project of an MSI for MVVM Light. Unfortunately, Leon was not able to complete this initiative, but the very helpful and capable Morten Nielsen created the installer in Wix. This gave me the occasion to learn Wix (I had only created setups with the Visual Studio setup project so far), and to tweak the installer. I am really grateful to Morten for his time!

Yesterday, I published the automated installer for MVVM Light V3. This installer contains binaries, project and item template as well as code snippets for Silverlight 3, Silverlight 4, WPF3.5SP1, WPF4, Windows Phone 7.0 and Windows Phone 7.5 “Mango”. It allows you to develop in Visual Studio 2008, Visual Studio 2010, Expression Blend 4 and/or Visual Studio Express for Windows Phone.

Update: The previous version has issues on non-English systems. This issue has been corrected now (as of 1st of September 2011).

And then?

A lot of people asked me when MVVM Light V4 will be published. As I mentioned above, I will release a beta 1 very soon. Beta 1 means that the API should be reasonably stable. I do however have more things I want to fix, so I am also planning a beta 2 before I hit RTM. The goal with beta 2 is to let people test my fixes, just to make sure that I didn’t break anything (yes I do run quite a few unit tests in all available frameworks, but… errare humanum est!).

It is really hard for me to give a precise timeline for those releases, because of work, a new house that we are moving to in August, my wonderful family who also requires some of my time here and there and my greedy Kindle 3 (just finished A Dance with Dragons, that one was pretty amazing). However roughly put, it looks like this:

MVVM Light V4 beta 1 before end of August.
MVVM Light V4 beta 2 not too long after that.
MVVM Light V4 RTM not too long after that

More than ever, I am amazed and delighted at the great feedback I receive from the MVVM Light community. This is not a perfect product, but your continuous constructive feedback keeps me motivated to continue developing and making this toolkit better. Thanks for your fantastic support!

Happy coding!

Laurent

Laurent Bugnion (GalaSoft)
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Proposing a new RelayCommand snippet for MVVM Light V4

Laurent Bugnion — Wed, 15 Jun 2011 14:39:30 GMT

In MVVM Light V4, I am proposing a new RelayCommand snippet, making it easier to declare and initialize a RelayCommand. I came up with a syntax that allows having the RelayCommand and its initialization in one convenient location.

I am looking for feedback, so leave your comments below!!

RelayCommand

This is the code created by the code snippet after expansion, for a simple RelayCommand.

private RelayCommand _testCommand;

/// <summary>
/// Gets the TestCommand.
/// </summary>
public RelayCommand TestCommand
{
    get
    {
        return _testCommand ?? (_testCommand = new RelayCommand(
            () =>
            {
                // Execute delegate
                throw new NotImplementedException();
            },
            () =>
            {
                // CanExecute delegate
                throw new NotImplementedException();
            }));
    }
}

RelayCommand<T>

This is the code created by the code snippet after expansion, for a generic RelayCommand (with parameter).

private RelayCommand<string> _testAgainCommand;

/// <summary>
/// Gets the TestAgainCommand.
/// </summary>
public RelayCommand<string> TestAgainCommand
{
    get
    {
        return _testAgainCommand ?? (_testAgainCommand = new RelayCommand<string>(
            p =>
            {
                // Execute delegate
                throw new NotImplementedException();
            },
            p =>
            {
                // CanExecute delegate
                throw new NotImplementedException();
            }));
    }
}

Conclusion

Do you find this way of creating the RelayCommands convenient? This limits the number of key press to a minimum (the only parameters to enter are the attribute name, the command’s name and (in the case of the generic RelayCommand) the type of the parameter. Looking for feedback before I consolidate this for V4!

Happy coding!

Laurent

Laurent Bugnion (GalaSoft)
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Is your application powered by #mvvmlight?

Laurent Bugnion — Fri, 20 May 2011 16:56:31 GMT

A couple of days ago I had the wonderful surprise to find a mention (and a link!) to MVVM Light on USAToday.com. The article talks about the new USA Today app available for Windows Phone 7. MVVM Light is mentioned as well as JSON.NET just after the high quality of the development tools is mentioned:

“That same high bar for tools extends into the community as well. MVVM Light and JSON.Net were extremely useful moving past mundane tasks and instead getting to the business of building our app.” – Tim Carlson, USA TODAY

This is of course fantastic, but it made me realize that I did not, until now, keep track of what applications (in Windows Phone 7 but also Silverlight and WPF) use MVVM Light to facilitate the development.

An appeal to MVVM Light users

In order to correct this, I would love to hear from you. Do you use MVVM Light? Did you publish an application (WP7, Silverlight, WPF) using the bits? If yes, do you mind answering the following optional questions:

What is the name and homepage of your project?
What framework is it? (WP7, Silverlight, WPF?)
Do you allow me to use this info for promotion (on the MVVM Light Toolkit’s page, or in conferences)? (if you prefer me to keep this info confidential, you have my assurance that I will happily comply).

Feel free to answer in the comments below, or per email to laurent@galasoft.ch. This is, in advance, very much appreciated!

Happy coding,
Laurent

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MVVM Light V3 on NuGet (now with WP7 support)

Laurent Bugnion — Sat, 07 May 2011 20:18:31 GMT

There was already a version of MVVM Light on Nuget before. However the old version did not support Windows Phone 7. This is now corrected. Also the new version now adds a ViewModelLocator to your project and includes it in App.xaml.

What is NuGet?

NuGet is a mechanism allowing to add packages (assemblies, source code…) to an existing project. All versions of MVVM Light are supported (WPF3.5, WPF4, Silverlight 3, Silverlight 4, Windows Phone 7).

In order to install NuGet and learn more about this cool package manager, go to http://nuget.org

Finding and installing MVVM Light with NuGet

To find MVVM Light in NuGet, follow the steps:

Open your project in Visual Studio 2010.
Right click on the References folder and select “Add Library Package Reference” from the context menu.

Note: Should that menu item be missing, you need to install the NuGet package manager. Go to http://nuget.org and follow the indications.

In the “Search Online” field, enter “mvvmlight” and press Enter.
Select the MVVM Light package and press the Install button.

After these steps, the following changes have been made to your project:

A “packages” folder was added with the following libraries. Note that this folder is added to the root of the project structure and does not appear in the Solution Explorer.
- The MVVM Light DLLs: GalaSoft.MvvmLight and GalaSoft.MvvmLight.Extras.
- The referenced System.Windows.Interactivity.dll, needed by the GalaSoft.MvvmLight.Extras assembly.
A ViewModel folder was added with two additional classes:
- ViewModelLocator.cs
- MainViewModel.cs
The App.xaml file was modified with the addition of the ViewModelLocator as global resource.

Binding the DataContext in XAML

With the new file structure, the ViewModelLocator is exposed in App.xaml (global resources) and can be used as the source of the DataContext bindings.

The MainViewModel that has also been added to the project is exposed in the ViewModelLocator as a property. for more details about this architecture, please refer to Understanding the MVVM pattern and Deep Dive MVVM.

Note: In case you do not need the MainViewModel in your project, feel free to remove this class.

In order to use the MainViewModel as the DataContext of the MainPage or MainWindow, use the following steps:

Open MainPage.xaml or MainWindow.xaml.
Add the following line to the opening tag of the MainPage/MainWindow:

DataContext="{Binding Main, Source={StaticResource Locator}}"

From now on, the DataContext of the MainPage/MainWindow is set to the instance of MainViewModel exposed by the ViewModelLocator. These steps can be repeated at will with different views/viewmodels pairs.

Binding the DataContext in Blend

The DataContext can also be databound visually in Expression Blend with the following steps.

Open your project in Blend.
Build the application.
Open MainPage/MainWindow.
In the Objects and Timeline panel, select the UserControl.
In the Properties panel, select the DataContext property (in the Common Properties section).
Click on the small Advanced options peg right of the property field and select Data Binding from the context menu.

In the Data Binding editor, select the Data Field tab and the Locator data source. Note: If you don’t see the Locator field, you need to build the project.

In the Fields area, expand the ViewModelLocator and select the Main property. Then press OK to close the Data Binding editor.

Installing without the ViewModel folder (libraries only)

Some users prefer to work without a ViewModelLocator, and are only interested in the MVVM Light assemblies. Unfortunately there is not really a way to specify options when using NuGet. So I created a different “barebone” package, named “MvvmLightLibs” which contains only the libraries and nothing else. To install this “barebone” version, follow the steps above, but select “MvvmLightLibs” instead of MvvmLight.

Installing from the command line

There is also a way to use NuGet without Visual Studio, from the command line. A good description is available on this blog.

Tell me what you think!

I am very interested to know what you guys think of the experience with NuGet. Please let me know if you like it!

Laurent Bugnion (GalaSoft)
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MVVM Light V4 preview 3 (BL16, MIX11 edition!!) #mvvmlight

Laurent Bugnion — Thu, 14 Apr 2011 14:16:49 GMT

At MIX11, I am releasing a new preview of MVVM Light version 4. This new preview contains one small change and one large change.

ObservableObject replaces NotifyPropertyChanged

In the previous preview, I introduced a new class named NotifyPropertyChanged. However, I got a few suggestions to rename this class to ObservableObject, which is indeed a better name. In BL16, NotifyPropertyChanged was deleted and replaced by ObservableObject. Nothing else changes, just the name.

ObservableObject is a very simple implementation of INotifyPropertyChanged suitable for data objects (in the Model, typically) that need to raise the PropertyChanged event, but that are not quite ViewModels. In my MIX11 session, I demo a usage of ObservableObject to build an application using JSON. In WCF, we don’t really need ObservableObject, since all the generated proxies will automatically implement INotifyPropertyChanged.

We have:

Introducing SimpleIoc, a simple IOC container

Last year at MIX10, I did a demo using the Unity IOC container. This helper simplifies the creation and the resolution of services and of the ViewModels, and allows for a cleaner syntax in the ViewModelLocator. Since then, I have tried a multitude of variants for the ViewModelLocator class, and I still came back, over and over again, to the same idea: using an IOC container to do the bulk of the work.

However, I did not want to settle on a given IOC container. There are so many of them, each with specific features, and each with an army of followers so instead… I created my own. Well, to be honest I inspired myself strongly from an existing simple IOC implementation, and I extended it with features that are super useful when working with ViewModels. Also a source of inspiration, the SimpleServiceLocator available on Codeplex.

A more complete article dedicated to the SimpleIoc class in MVVM Light V4 will follow. Also, my MIX11 session “Deep Dive MVVM” features the SimpleIoc in the samples. The session’s recording is available at http://channel9.msdn.com/Events/MIX/MIX11/OPN03.

Cheers,

Laurent

Laurent Bugnion (GalaSoft)
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