Using Entity Framework's New POCO Features: Part 1, by Julie Lerman

Using POCOS in Entity Framework 4Part 1
Julie Lerman
thedatafarm.com/blog
jlerman@thedatafarm.com
Julia Lerman October 17th 2009, New England Code Camp 12

Note to Viewers
This is Part 1 of a two part presentation. Part 2 covers testing and other patterns and how EF4 supports them. It was presented by Jamie Phillips. You can find his presentation at
http://devblog.petrellyn.com/?p=189

Julie Lerman
website
theDataFarm.com
blog & twitter
theDataFarm.com/blog@julielermanVT
book web site
LearnEntityFramework.com
consultant/mentor
Microsoft MVP, INETA Speaker,ASPInsider, MCP, VTdotNET Leader

Agenda
Standard EntityObject Classes
Simple POCO Classes
POCO and Proxies
Generate POCO Classes with T4
Code-Only Development

EF1 & Default EF4 Gen’d Classes
CustomTool=EntityModelCodeGenerator

POCO: Plain Old CLR Object
Define your classes
Not bound to other APIs
e.g. no inheritance from EntityObject
Classes are reusable
Simplifies testing
and more…

How Does EF4 Support POCO?
EntityObjects interact with context
For POCO, context does all of the work
Classes don’t need to know about context
Help provided by
Special context methods
Additional support via proxies

Basic POCO Support
Turn off code generation from EDMX
“Convention” will auto-map classes/entities

POCO and Other EF Features
Complex Types: Supported
Use a class (no structs) to represent the type
Lazy Loading
Declare property as virtual
EF uses a proxy instance at runtime to load
Explicit Loading
ObjectContext.LoadProperty(myObj,”PropertyName”)
ObjectCOntext.LoadProperty(myObj, o=>o.property)

Change Tracking Options
Snapshot
Default change tracking
Collected with DetectChanges is called
Notification based
virtual properties use Proxies
Proxies can provide notification to context

POCO Classes from Model
T4
Text Template Transformation Toolkit

Code-Only Design
Part of the Feature CTP
No model at all
Metadata is inferred from classes
Convention by Default
EF will rely 100% on presumptions
Configuration Follows
Tweak configurations to modify behavior

Self-Tracking Entities
Part of Feature CTP
T4 Template to create specialized POCO classes
EntityState is tracked by entity
Specialized methods that know what to expect from the classes

Resources
LearnEntityFramework.com/resources
blogs.msdn.com/adonet, efdesign, dsimmons, alexj, more...
msdn.microsoft.com/data
Gateway to whitepapers, forums, documentation

Contact
website
theDataFarm.com
blog & twitter
theDataFarm.com/blog@julielermanVT
book web site
LearnEntityFramework.com
consultant/mentor
Microsoft MVP, INETA Speaker,ASPInsider, MCP, VTdotNET Leader