Definition of Terms: Models Models Are… …the “M” in MVC, MVP, MVVM Model View Controller Model View Presenter Model View ViewModel …the Data …the “Single Source of Truth” …Behavioral (methods)
Definition of Terms – Repositories Repositories are… …a way to get a model …a way to save changes to a model Persistence Ignorance… …hides data storage / access choices RDO, ADO, ADO.NET Nhibernate, EF, Linq2SQL …separates concerns …makes unit testing easier
Entity Framework – Model Designer & Code Generator Entity Framework: Model Designer -Database First -Model First Code Generator (T4 Templates) -Default Template -Self Tracking Entities Template -Plain Old CLR Objects (POCO) Template
Entity Framework – Self Tracking Entities Self Tracking Entities… Originally designed to enable EF over WCF 1)Share entity dll with client 2)Client entities track their changes 3)Changes sent back to service 4)Service applies changes to context But… works great for the Desktop too!
Entity Framework – Build your own Repository Goals for a Repository: 1)Use interfaces for definition 2)Expose methods to get, save and query 3)Keep all EF “stuff” inside. a.Clients should not need a reference to System.Data.Entities
Entity Framework – Repository Demo Demo – EF Basics EF Model Getting and Applying the STE template Separating entities into separate project Interfaces for repository Multiple Repositories: SQL & XML
Entity Framework – Repository Tips Demo – EF Tips & Tricks Loading Children From the DB .Include(“”) vs. LoadProperty(o => o.Child) Saving ApplyChanges(), SaveChanges() MarkAllAddedAsUnmodified(), RefreshAll() AcceptAllChanges(), StartTrackingAll() Deletes Parent.Remove() does not delete the record…
Entity Framework – Template Tips Demo – T4 Customizations Partial Classes / Methods Partial Classes = Custom Logic / Properties Partial Methods = Hooks into property changes Undo Hooks T4 includes calls to UndoService for property changes OnInitializing() & OnInitialized() Works with DelayedInitializationScope
Entity Framework – Delayed Initialization Scope Demo - Delayed Init Scope Entities call RegisterForEndInit() … Then EndInit() called after last scope completes Use in a using block Supports nesting ThreadStatic variables to track “current” Callers can check whether a scope is active
Entity Framework – Undo / Redo Tracking Demo – Undo / Redo Tracking Each setter tells Undo framework about change SelfTrackingEntityUndoService.OnChanging() Undo framework adds a “change” to the undo stack Each “change” knows how to apply the previous value More on this later
WPF – App Goals Goals for the Demo App Good Architecture… … Community says MVVM for WPF / SL. “Single Source of Truth” rendered in one or more views, which stay in sync as data changes in the model. Model contains core data and behavior. View-specific concerns are in the ViewModel or View. Undo / Redo support
WPF – Bindings and INotifyPropertyChanged WPF Bindings & INotifyPropertyChanged WPF means Powerful Binding Support! Two-Way bindings require Change Notification WPF UI elements use DependencyProperties for change notification. What about the model…???
WPF – Bindings and INotifyPropertyChanged Model Change Notification: System.ComponentModel.INotifyPropertyChanged Primary way to tell WPF that a property value changed System.Collections.ObjectModel.ObservableCollection Primary way to tell WPF that a collection changed Implements INotifyCollectionChanged Raises an event whenever items added, removed, replaced or relocated.
WPF – Using an Entity Framework Model Using a Model – Self Tracking Entities Partial Methods Revisited Raising PropertyChanged for “dependent” properties Validating data Undo / Redo Support Importance of INPC for Undo – It changes the model Available from http://muf.codeplex.com/http://muf.codeplex.com/ Hooking it up – Commands Optimizations – Undo Batches
WPF – Dealing with ViewModels Dealing With ViewModels “Completing the INPC loop” Snippets for Implementing INPC –On My Blog (http://blog.alner.net/...)On My Blog (http://blog.alner.net/...) Remember to raise PropertyChanged for “dependent” properties Crazy Cool: ContinuousLinq’s ReactiveObject –http://clinq.codeplex.com/http://clinq.codeplex.com/
WPF – Tips and Tricks WPF Tips and Tricks Keyboard Focus Toolbars don’t cause “LostFocus” event Use the CommitBindingsBehavior to force bindings. Demo…
WPF – Tips and Tricks WPF Tips and Tricks Design Time & “Blendability” Use “design-time” detection to populate ViewModels. Demo…
WPF – Tips and Tricks WPF Tips and Tricks Threading Use the BackgroundWorker for lengthy operations Marshal all changes back to UI thread via: –Dispatcher.Invoke() / BeginInvoke() –SynchronizationContext.Send() / Post() Warning! Collections are problematic. Some solutions exist, but each has problematic edge cases. T4 Template includes SynchronizedContextCollection, which attempts to marshall changes to UI via SynchronizationContext.
WPF – Weak References & Weak Events FYI: Weak References & Weak Events WPF uses these extensively Critical to allowing the GC to collect memory Important when you have GC roots holding on to things (like static instances). May need a memory profiler. Event Handlers create a reverse reference. If you don’t disconnect, it might lock things in memory.
WPF – ViewModel Locators ViewModel Locator Options Code-behind / Resource MVVM Light – Smart Resource Caliburn – ViewModel-First (awesome framework!) MEFed MVVM – Using MEF to create ViewModels My Preference: Converter Based Locators Demo (if time permits)
Thanks! Congratulations! We made it to… The End! (If you’d like more info one of these topics, let us know)
Thanks! Thanks! See you next month! (Please turn in evals) Nathan Allen-Wagner.NET Architect - Bennett Adelson firstname.lastname@example.org Bloghttp://blog.alner.net Podcasthttp://NorthCoastCodeCast.net Twitter@nathanaw
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