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THE MODEL-VIEW-VIEWMODEL (MVVM) DESIGN PATTERN FOR WPF

THE MODEL-VIEW-VIEWMODEL (MVVM) DESIGN PATTERN FOR WPF
Patterns WPF Apps With The Model-View-ViewModel Design Pattern Josh Smith Developing the user interface of a professional software application is not easy. It can be a murky blend of data, interaction design, visual design, connectivity, multithreading, security, internationalization, validation, unit testing, and a touch of voodoo. There are popular design patterns that can help to tame this unwieldy beast, but properly separating and addressing the multitude of concerns can be difficult. It is not always the design patterns at fault. As the software world continues to adopt WPF at an increasing rate, the WPF community has been developing its own ecosystem of patterns and practices. By the end of this article, it will be clear how data templates, commands, data binding, the resource system, and the MVVM pattern all fit together to create a simple, testable, robust framework on which any WPF application can thrive. Order vs. The Evolution of Model-View-ViewModel The Demo Application

MVVM Compared To MVC and MVP Saturday, November 21, 2009 6:53 PM At the recent Calgary Tech Days event I did a presentation on building composite applications with WPF and Silverlight. One question that I get asked frequently when I get to the part of explaining MVVM is how its different from patterns that seem too similar or identical, with MVC and MVP typically being the two common ones raised. Usually my answer is that MVVM is very similar to the others, but it implies *stuff* that’s specific to Silverlight and WPF (how binding works, commanding, etc.). So below I have a comparison, pointing out the key differences between the patterns and why MVVM *is* different. MVC – Model View Controller Let’s look at MVC first. The input is directed at the Controller first, not the view. There is a many-to-one relationship between the Controller and the View. Note the one way arrow from Controller to View. MVP – Model View Presenter Now let’s look at the MVP pattern. The input begins with the View, not the Presenter. Conclusion

wpf - Good examples of MVVM Template WPF Model-View-ViewModel (M-V-VM) Example Tracy Sells When starting out with WPF and the M-V-VM pattern I was looking for a simple example of this pattern. Most of the things I found were full of items that complimented the pattern but didn’t show just the pattern itself. I decided to walk through a simple example and will detail it below. You can download the source code from here. Basic M-V-VM OverView The Model The model in the MVVM pattern will be the business object. NameFile PathHeightWidth It also contains a validation method to validate the Picture object. Base Model Class This class is used to provide functionality to each model class without the need to replicate code. The View Model The view model contains the UI logic for the view. The view model contains a collection of picture objects. Properties Error Message – displayed when error occursPictures – observable collection of Picture Objects (Model). Methods Base View Model Class This class is used to provide functionality to each view model class without the need to replicate code.

Evaluation of MVVM « Zeeshan Amjad's WPF Blog Let’s take a look at MVVM from higher level and take a step by step approach to understand it. Here our discussion is based on complexity of the architecture from simple to complex, not from historical order. Probably the simplest design principle to separate the data from its presentation is Observer design pattern. In observer design pattern, we have two different classes for data (subject/model) or its presentation (observer/view). Subject class contain the instance of all of the observers and send notification to all of observers when there is any change in the data. The next step is to introduce middle layer in between data and its presentation. This approach has some advantages and disadvantages. MVVM is very similar to MVP pattern. Now let’s take a look at MVVM little bit more detail. This diagram explain how can we take advantage of MVVM. Like this: Like Loading...

Dependency Properties Overview In WPF, properties are typically exposed as common language runtime (CLR) properties. At a basic level, you could interact with these properties directly and never know that they are implemented as a dependency property. However, you should become familiar with some or all of the features of the WPF property system, so that you can take advantage of these features. The purpose of dependency properties is to provide a way to compute the value of a property based on the value of other inputs. Following is a summation of the terminology that is used in this software development kit (SDK) documentation when discussing dependency properties: public static readonly DependencyProperty IsSpinningProperty = DependencyProperty.Register( "IsSpinning", typeof(Boolean), ... ); public bool IsSpinning { get { return (bool)GetValue(IsSpinningProperty); } set { SetValue(IsSpinningProperty, value); } } You can set properties either in code or in XAML. Button myButton = new Button(); myButton.Width = 200.0;

Painless Functional Specifications - Part 1: Why Bother? by Joel Spolsky Monday, October 02, 2000 When The Joel Test first appeared, one of the biggest sore points readers reported had to do with writing specs. It seems that specs are like flossing: everybody knows they should be writing them, but nobody does. Why won't people write specs? I believe that on any non-trivial project (more than about 1 week of coding or more than 1 programmer), if you don't have a spec, you will always spend more time and create lower quality code. The most important function of a spec is to design the program. Let's visit two imaginary programmers at two companies. Speedy and Mr. Speedy decides that the best way to provide backwards compatibility is to write a converter which simply converts 1.0 version files into 2.0 version files. Now, Mr. When opening a file created with an older version of the product, the file is converted to the new format. The spec is shown to the customer, who says "wait a minute! Another 20 minutes have elapsed. Mr. 20 more minutes. Mr.

WPF patterns : MVC, MVP or MVVM or…? :: Orbifold Introduction Since XAML things have become a bit complicated in trying to conceptualize MVC architectures for Windows applications. The gap between web and win is narrowing and the whole WPF thing adds diverse possibilities to one's toobox. What to use? What's the problem? WPF has changed a few things: through declarative programming (i.e. The MVVM architecture Overview DataModel DataModel is responsible for exposing data in a way that is easily consumable by WPF. The model Using the INotifyPropertyChanged you can bubble changes up the stack. Dispatcher things The DispatcherTimer is reevaluated at the top of every Dispatcher loop. the timer is injected implicitly in the thread associated to the dispatcher of the UI. References

Model-View-ViewModel (MVVM) Explained The purpose of this post is to provide an introduction to the Model-View-ViewModel (MVVM) pattern. While I've participated in lots of discussions online about MVVM, it occurred to me that beginners who are learning the pattern have very little to go on and a lot of conflicting resources to wade through in order to try to implement it in their own code. I am not trying to introduce dogma but wanted to pull together key concepts in a single post to make it easy and straightforward to understand the value of the pattern and how it can be implemented. MVVM is really far simpler than people make it out to be. Click here to read the Spanish version (Leer en español) Want to learn about MVVM in the HTML5 age? Why Even Care About MVVM? Why should you, as a developer, even care about the Model-View-ViewModel pattern? Do you need to share a project with a designer, and have the flexibility for design work and development work to happen near-simultaneously? Let's examine the pieces of the MVVM pie.

.NET Design Patterns in C# and VB.NET - Gang of Four (GOF) - DoFactory Design patterns are solutions to software design problems you find again and again in real-world application development. Patterns are about reusable designs and interactions of objects. The 23 Gang of Four (GoF) patterns are generally considered the foundation for all other patterns. They are categorized in three groups: Creational, Structural, and Behavioral (for a complete list see below). To give you a head start, the C# source code for each pattern is provided in 2 forms: structural and real-world. Structural code uses type names as defined in the pattern definition and UML diagrams. A third form, .NET optimized, demonstrates design patterns that fully exploit built-in .NET 4.5 features, such as, generics, attributes, delegates, reflection, and more.

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