Entity Framework NYC Firestarter

NYC
Entity Framework
Firestarter

Speakers

Entity Framework Firestarter
Schedule

Thanks Microsoft
For Hosting and Lunch

EF NYC Firestarter
Part 1: It’s Time to Look at Entity Framework
Julie Lerman
thedatafarm.com/blog
twitter @julielerman

Julie Lerman
website
theDataFarm.com
blog & twitter
theDataFarm.com/blog@julielerman
book web site
LearnEntityFramework.com
consultant/mentor
Microsoft MVP, INETA Speaker,ASPInsider, MCP, VTdotNET Leader
NYC Entity Framework Firestarter, Sept 27th 2010

Why Entity Framework?
Object Relational Mapper
ADO.NET
Data
Set
ADO
Record
Set
Entity
Framework
Object
Spaces

Design Time: EDMX
EF Metadata vs Other ORMs
DB
DB
EF Runtime Metadata (XML files)
Conceptual Model
Schema
Database
Structure
Schema
Designer Layout & Positioning
Typical ORM
Objects

ADO.NET Today & Tomorrow
DataSet
Entity Framework
LINQ to SQL

Model in Entity Framework
Model
First
Database
First
New
Database
Legacy
Database
Code
First
“M”

Entity Framework
Conceptual Model in your Apps
UI
DB
Conceptual
Model
of your Domain
App Logic
Provider
Query
Track Changes
Repository
Updates to DB
Business
Objects

Time to Code
A little modeling…
A little querying…
A little editing…
A little saving…

FAQS
Stored Procedure Support
Use Views & Stored Procs – no table access
Update the model when DB changes
Mappings are highly customizable
Inheritance
Many to Many
Merge tables
Split tables
etc
Pass through queries & commands

Entity Framework Everywhere

Why Entity Framework Summary
Microsoft’s in-the-box ORM
Focus of Microsoft/.NET data access
Use any back end db (with a provider)
Use in any type of .NET application
Backbone of many Microsoft technologies

Part 2:What’s new in Entity Framework 4
EF NYC Firestarter
Steve Bohlen
unhandled-exceptions.com/blog
twitter @sbohlen

Long Form: Comprehensive
Model-first development
Automatic pluralization
Foreign keys in models
POCO class support
Lazy loading
T4 Code Generation
Template customization
IObjectSet
Virtual SaveChanges
ObjectStateManagercontrol
Self-tracking entities
SQL generation improvements
More LINQ operator support
LINQ extensibility
ExecuteStoreQuery
ExecuteStoreCommand
SPROC import improvements
Model defined functions
WPF designer integration
Code-First development (Feature CTP)

Short Form: Highlights
Designer Improvements
Foreign Keys
New Code Generation
Persistence Ignorance
Change Tracking for WCF
Better n-tier Support
Lazy Loading
Code-Only Development

Designer Improvements
Pluralization Support
Generate Database from Model
vs. only Reverse-Engineering in v1
Improved SPROC Support
SPROCs can return only entities in v1
SPROCs can return strongly-typed projections in v4

Foreign Key Support
ERM vs exposed FKs (it’s a CHOICE via the dialog box)
Does NOT replace the Nav properties
DataContext is able to leverage this for some efficiencies
Changing either the FK or the Nav property changes the other value (due to code-gen support)

Code Generation
Model  templates  Classes
Code Generation Engine now T4 instead of proprietary engine in v1
Tools support/syntax support resources
review a quick look at the T4 syntax
T4 Editor add-in

(better) Persistence Ignorance
EntityObject inheritance NOT required
Snapshot-based
No lazy loading support in this approach
No Change Tracking
must call ObjectContext.DetectChanges( )
ObjectContext.Save( ) implicitly calls .DetectChanges( )
Proxy-based
virtual keyword is the ‘flag’ for this behavior
virtual on all  change-tracking and lazy-load
virtual on just navigation props  only lazy-loading
Several Canned Templates

WCF and Self-Tracking Entities
T4 template for self-tracking entities
Passing objects across serialization boundaries

Lazy Loading
v1 supported only explicit load of lazy collections
ObjectContext.ContextOptions.LazyLoadingEnabled = true
by default in NEW models, but NOT in imported v1 models
Behavior scoped at the ObjectContext
NOT at property level for entities
Toggle-able before and after operations for query-specific granular lazy-loading behavior

Explicit State Management
ObjectContext.ApplyCurrentValues( )
Formerly ApplyPropertyChanges( ) in v1
ObjectContext.ApplyOriginalValues( )
ObjectStateEntry.ChangeState( )
Unchanged/Added/Modified/Deleted
ObjectStateManager.ChangeRelationshipState( )

Code-Only Support
‘Feature CTP’
Classes  Entities
Entities  Database (optionally)
No Model Necessary
Heavily Convention over Configuration

Miscellaneous
Model-Defined Functions
ObjectSet (collections of entities)
Complex Type Support
Query optimization (E-SQL, LINQ2Entities)
ExecuteCommand/Defined Queries/Model Functions
Designer support for more features without direct editing of .csdl, .ssdl, .edml

Part 4: Getting Started with POCOs in EF4
EF NYC Firestarter
Julie Lerman

Agenda
Simple POCO Classes
Leveraging Proxies
Customizable T4 Code Generation

POCO
Plain Old CLR Objects

Benefits
Use existing classes
Loose Coupling
Classes have no dependency on EF
Persistence Ignorance
Unit Testing
Repositories & Unit Of Work Patterns

ObjectContext Manages Entities
POCO
“Snapshot”4.0
EntityObject
(3.5 & 4.0)
ObjectContext
Person Object
State info
State info
Order Object
State info
Detail Object
State info
Detail Object
State info
Order Object
State info
Detail Object
State info
Detail Object

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

POCO and Other EF Features
Complex Types
Use a class (no structs) to represent the type
Explicit Loading
ObjectContext.LoadProperty(myObj,”PropertyName”)
ObjectContext.LoadProperty(myObj, o=>o.property)
Two-Way Navigation
Must be coded into classes

Lazy Loading POCOs
virtual (Overridable) navigation properties
IRelatedEnd wrapper at run-time
LazyLoadingEnabled=true required
Selectively allow lazy loaded properties
publicList<CreditCard>CreditCards {get; set; }
virtualpublicPersonPerson {get;set; }
publicList<Order> Orders { get;set; }

ObjectContext Manages Entities
POCO
“Snapshot”4.0
POCO
+ Dynamic Runtime Proxy
(4.0)
EntityObject
(3.5 & 4.0)
ObjectContext
Person Object
State info
State info
Order Object
State info
Detail Object
State info
Detail Object
State info
Order Object
State info
Detail Object
State info
Detail Object

Dynamic Runtime Proxy Classes
Track
Lazy Load
Relationships
Person
class
F5
Mark all Entity (model) Properties virtual
Provides features similar to EntityObject
Change notification
Relationship management
Lazy Loading

Rules for Proxy Notification
All entity properties shall be virtual
Though shalt use ICollection<T>
Creation shall be done withObjectContext.CreateObject<T>
Classes shall not be sealed
Navigation properties shall not be sealed
Classes shall not be abstract
Classes shall have a parameter-less constructor

Code Gen POCOs from Model
T4
T
4
Text Template Transformation Toolkit

EF POCO Summary
POCO support is new to EF4
Alternative to EntityObjects
Simple snapshot POCOs or use proxies
Use or even customize T4 template for code generation
Enable many coding/architectural possibilities

Part 5: Disconnected Strategies for ASP.NET & Services
EF NYC Firestarter
Julie Lerman

Agenda
EF Challenges in Server Aps
Review Options with EF
EF4 Tools to the Rescue
POCOs and Repositories
Leveraging Foreign Keys
Putting it all together

Change Tracking Across Tiers
ObjectContext
ObjectStateEntry
SO1 EntityKey Original ValuesCurrent Values Other ∆ Info
ObjectStateEntry
SO2 EntityKeyOriginal ValuesCurrent ValuesOther ∆ Info
detach
entities
ObjectStateEntry
LIA EntityKeyOriginal ValuesCurrent ValuesOther ∆ Info
Original Property Values
EntityState Values
ObjectStateEntry
LIB EntityKeyOriginal ValuesCurrent ValuesOther ∆ Info

SaveChanges Fails Across Post Backs
Page Request
Post Back #1
Post Back #2
New Page Class
New Page Class
New Page Class
Create New ObjectContext
Create NewObjectContext
Create NewObjectContext
Get Entities
Process Request
Get Entities
Build HTML using Data & ASP.NET Markup
Destroy Page and Dependents

The Server Side Spectrum with EF
Dynamic Data forEntities
ObjectDataSource
WCF &
Self-Tracking Ents
EntityDataSource
MVC
WCF
Data
Services
Dev
WCF
ASP.NET
n-Tier
Architect

EF4 Changes to the Rescue
Foreign Keys
Big help for selected list values on postback
State Methods
ApplyCurrentValues, ApplyOriginalValues
ChangeState
ChangeRelationshipState (when no FKs)
POCO Classes & T4 Generation
Self-Tracking Entities for use with WCF

What about?
Graphs
Lazy Loading
Returning IQueryables
Change
Tracking

Oh, goody….
time for code…

Disconnected Strategies Summary
EF has inherent challenges across tiers
New tools in EF4 to enable disconnected

Part 6:Writing Testable/Maintainable Apps with EF
EF NYC Firestarter
Steve Bohlen
unhandled-exceptions.com/blog
twitter @sbohlen
Julie Lerman

Agenda
Setting the stage
Refactor a demo-worthy MVC app
Explore an existing solution with more complexity

“-ilities”
Benefits:
Extensibility
Adaptability
Testability
Maintainability
Quality 
Why should You Care?
Persistence Ignorance (PI)
Future-Proofing your investment

IObjectSet Abstraction
IObjectSet
Collection-like behavior
Add, Attach, Delete, etc.
ObjectSet
Concrete class
Implements IObjectSet
Inherits ObjectQuery
public class ObjectSet:ObjectQuery,IObjectSet

EF4 Goodness Makes This Work
POCOs
+
T4 Code Gen
Disconnected Methods
IObjectSet

Classes
PI/Repositories
System.Data.Entity
Fake
ObjectSet
Fake
Context & Data A
EDM &
ObjectContext
Fake
Context & Data B
Unit of Work
Class
Repositories
Class
Repositories
Class
Repositories
Repositories
UI
Tests

Resources
LearnEntityFramework.com/resources
thedatafarm.com/blog/tags/ef4
blogs.msdn.com/adonet, efdesign, dsimmons, alexj, more...
msdn.microsoft.com/data
Gateway to whitepapers, forums, documentation
Lots of bloggers on EF now! Google! 
-Bing!

Entity Framework NYC Firestarter

by Julie Lerman on Oct 04, 2010

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