Pro WPF and Silverlight MVVM Effective Application Development with Model-View-ViewModel

273 Pages·2010·4.174 MB·English

by  Gary Hall

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BOOKS FOR PROFESSIONALS BY PROFESSIONALS® THE EXPERT’S VOICE® IN WPF
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Pro WPF and Silverlight MVVM
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WPF and Silverlight are unlike any other user interface technologies. They have
been built to a new paradigm that—if harnessed correctly—can yield unprec-
edented power and performance. This book shows you how to control that W Pro
power to produce clean, testable, maintainable code.
Design and development experts now recognize that any non-trivial WPF P
or Silverlight application needs to be designed around the Model-View-
ViewModel (MVVM) design pattern in order to unlock the technology’s full F
Gary McLean Hall data-binding potential. But many coders still rely solely on programmatic WPF Silverlight
interaction between controls, because it's been hard for many to trust the WPF
data-binding technologies. a and
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Pro WPF and Silverlight MVVM shows you why that trust has been earned.
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Inside, discover how to create fast, scalable, and maintainable applications

using Silverlight and WPF. With this book, you’ll learn how to:
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MVVM
• Split view and model code apart to achieve a separation of concerns
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• Implement a ViewModel layer that mediates between the view and model
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• Apply automated unit tests to verify the quality of production code v
• Validate user input with a variety of techniques
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• Integrate a data access layer for persistently storing objects
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Effective Application Development with
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THE APRESS ROADMAP g
Pro Model-View-ViewModel
WPF in C# 2010
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ASP.NET MVC t
Introducing Framework
Silverlight 4 M
Pro
Silverlight 4 in C#
Companion eBook
Harness the power of WPF and Silverlight to
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WPF and produce clean, testable, maintainable code
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See last page for details
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Gary McLean Hall
SOURCE CODE ONLINE
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Pro WPF and
Silverlight MVVM
Effective Application Development with
Model-View-ViewModel

■ ■ ■
Gary McLean Hall

i
Pro WPF and Silverlight MVVM: Effective Application Development with Model-View-ViewModel
Copyright © 2010 by Gary McLean Hall
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For my wife, Victoria
iii
Contents at a Glance

■Contents ................................................................................................................ v(cid:1)
■About the Author ................................................................................................... x(cid:1)
■About the Technical Reviewer .............................................................................. xi(cid:1)
■Acknowledgments ............................................................................................... xii(cid:1)
■Introduction ....................................................................................................... xiii
■Chapter 1: Overview of WPF and Silverlight ......................................................... 1(cid:1)
■Chapter 2: DataBinding ....................................................................................... 21(cid:1)
■Chapter 3: Model-View Separation ..................................................................... 55(cid:1)
■Chapter 4: The ViewModel .................................................................................. 81(cid:1)
■Chapter 5: Events and Commands .................................................................... 111(cid:1)
■Chapter 6: Validation ......................................................................................... 129(cid:1)
■Chapter 7: Unit Testing ...................................................................................... 145(cid:1)
■Chapter 8: Data Access Layer ........................................................................... 163(cid:1)
■Chapter 9: Application Support ......................................................................... 185(cid:1)
■Chapter 10: Sample Application ........................................................................ 205(cid:1)
■Index ................................................................................................................. 243(cid:1)
iv
Contents

■Contents at a Glance ............................................................................................ iv(cid:1)
■About the Author ................................................................................................... x(cid:1)
■About the Technical Reviewer .............................................................................. xi(cid:1)
■Acknowledgments ............................................................................................... xii(cid:1)
■Introduction ........................................................................................................ xiii

■Chapter 1: Overview of WPF and Silverlight ......................................................... 1(cid:1)
WPF and Silverlight ......................................................................................................... 1(cid:1)
What Is WPF? ......................................................................................................................................... 1(cid:1)
What Is Silverlight? ................................................................................................................................ 5(cid:1)
Differences Between WPF and Silverlight .............................................................................................. 7(cid:1)
Multi-Target Platforms ........................................................................................................................... 9(cid:1)
XAML ............................................................................................................................. 13(cid:1)
Declarative User Interfaces .................................................................................................................. 13(cid:1)
XAML Elements .................................................................................................................................... 14(cid:1)
XAML Features ..................................................................................................................................... 16(cid:1)
User Experience vs. User Interface ............................................................................... 18(cid:1)
Summary ....................................................................................................................... 19(cid:1)
■Chapter 2: DataBinding ....................................................................................... 21(cid:1)
The Power of DataBinding with XAML .......................................................................... 21(cid:1)
Dependency Objects ............................................................................................................................ 21(cid:1)
Dependency Properties ........................................................................................................................ 23(cid:1)
Binding Sources ................................................................................................................................... 26(cid:1)
v
■ CONTENTS
Binding Modes ..................................................................................................................................... 28(cid:1)
The DataContext ................................................................................................................................... 30(cid:1)
Advanced DataBinding .................................................................................................. 31(cid:1)
Binding Parameters ............................................................................................................................. 31(cid:1)
Data Conversion ................................................................................................................................... 35(cid:1)
ObjectDataProvider .............................................................................................................................. 42(cid:1)
Debugging DataBindings ...................................................................................................................... 46(cid:1)
Templating ........................................................................................................................................... 49(cid:1)
Summary ....................................................................................................................... 53(cid:1)
■Chapter 3: Model-View Separation ..................................................................... 55(cid:1)
Separation of Concerns ................................................................................................. 55(cid:1)
Dependencies ...................................................................................................................................... 55(cid:1)
MVVM Alternatives ............................................................................................................................... 59(cid:1)
The Model ..................................................................................................................... 66(cid:1)
Encapsulation ....................................................................................................................................... 66(cid:1)
Don’t Repeat Yourself (DRY) ................................................................................................................. 67(cid:1)
You Ain’t Gonna Need It (YAGNI) .......................................................................................................... 69(cid:1)
The Law of Demeter ............................................................................................................................. 70(cid:1)
Test-Driven Development .................................................................................................................... 71(cid:1)
The View ....................................................................................................................... 73(cid:1)
Data Representation ............................................................................................................................ 73(cid:1)
User Input ............................................................................................................................................. 73(cid:1)
Data Binding ......................................................................................................................................... 74(cid:1)
Separating Model from View ......................................................................................... 75(cid:1)
The Mediator Pattern ........................................................................................................................... 75(cid:1)
Other Model-View-X Implementations ................................................................................................. 77(cid:1)
You Gotta Keep ’Em Separated ............................................................................................................ 78(cid:1)
Summary ....................................................................................................................... 79(cid:1)
■Chapter 4: The ViewModel .................................................................................. 81(cid:1)
First ViewModel ............................................................................................................ 81(cid:1)
vi
■ CONTENTS
The MVVM Template Project ................................................................................................................ 81(cid:1)
.NET Framework Interfaces and Classes ...................................................................... 90(cid:1)
Observer Pattern .................................................................................................................................. 90(cid:1)
INotifyPropertyChanged Interface ........................................................................................................ 91(cid:1)
Observable Collections ......................................................................................................................... 92(cid:1)
CollectionViewSource .......................................................................................................................... 94(cid:1)
Constructing ViewModels .................................................................................................................... 96(cid:1)
Handling Concurrency ................................................................................................. 100(cid:1)
Threading ........................................................................................................................................... 100(cid:1)
Threading Problems In WPF and Silverlight ....................................................................................... 104(cid:1)
Updating the UI .................................................................................................................................. 107(cid:1)
Summary ..................................................................................................................... 110(cid:1)
■Chapter 5: Events and Commands .................................................................... 111(cid:1)
Events ......................................................................................................................... 111(cid:1)
Events in .NET .................................................................................................................................... 111(cid:1)
Events in WPF and Silverlight ............................................................................................................ 112(cid:1)
Commands .................................................................................................................. 115(cid:1)
Command Pattern .............................................................................................................................. 116(cid:1)
The RelayCommand ........................................................................................................................... 119(cid:1)
Attached Command Behavior ............................................................................................................. 126(cid:1)
Avoiding Events Using Dependency Injection .................................................................................... 126(cid:1)
Summary ..................................................................................................................... 128(cid:1)
■Chapter 6: Validation ......................................................................................... 129(cid:1)
The Validation Process ................................................................................................ 130(cid:1)
Binding Validation Rules ............................................................................................. 131(cid:1)
ValidationRule Class ........................................................................................................................... 131(cid:1)
Exceptions for Validation .................................................................................................................... 133(cid:1)
A Validation Framework ..................................................................................................................... 135(cid:1)
IDataErrorInfo Interface ...................................................................................................................... 135(cid:1)
DataErrorValidationRule Class ........................................................................................................... 139(cid:1)
vii
■ CONTENTS
Validation in Silverlight ............................................................................................... 139(cid:1)
Visually Formatting Validation Errors .......................................................................... 143(cid:1)
Validation.ErrorTemplate Attached Property ...................................................................................... 143(cid:1)
Validation.HasError Attached Property ............................................................................................... 143(cid:1)
Summary ..................................................................................................................... 144(cid:1)
■Chapter 7: Unit Testing ...................................................................................... 145(cid:1)
The Importance of Testing .......................................................................................... 145(cid:1)
Traditional Testing ............................................................................................................................. 145(cid:1)
What Is Unit Testing? ......................................................................................................................... 149(cid:1)
Why Unit Test? ................................................................................................................................... 151(cid:1)
How to Unit Test .......................................................................................................... 152(cid:1)
Unit Testing with Visual Studio 2010 ................................................................................................. 152(cid:1)
Writing Tests ...................................................................................................................................... 158(cid:1)
Summary ..................................................................................................................... 162(cid:1)
■Chapter 8: Data Access Layer ........................................................................... 163(cid:1)
Object-Relational Dichotomy ...................................................................................... 163(cid:1)
DAL Implementations .................................................................................................. 172(cid:1)
Manual Implementation ..................................................................................................................... 172(cid:1)
Third-Party Implementations ............................................................................................................. 176(cid:1)
Supporting Patterns .................................................................................................... 180(cid:1)
The Repository Pattern ....................................................................................................................... 180(cid:1)
Unit of Work ....................................................................................................................................... 181(cid:1)
Creating the Data Schema .......................................................................................... 182(cid:1)
Generate, Not Create .......................................................................................................................... 182(cid:1)
Summary ..................................................................................................................... 183(cid:1)
■Chapter 9: Application Support ......................................................................... 185(cid:1)
Serialization ................................................................................................................ 186(cid:1)
Serializing POCOs ............................................................................................................................... 186(cid:1)
Extensibility ................................................................................................................. 192(cid:1)
viii