deck from our talk at DevTeach

1. Real-world Entity Framework
Llewellyn Falco – A Developer’s Developer
Lynn Langit – A DBA and more

2. Agenda
Query
Save
Patterns

3. What is Entity Framework 4?
Object Relational Mapper (ORM)
•Included in .NET 4.0
•Developers write .NET code
• using LINQ
• generate database access
code

4. Generating a Model
DEMO - startING with EF

5. What did we just do?
• Created a new project in Visual Studio
• Added a new ADO.NET Entity Model
• Generated a model from a database
• Reviewed the generated model
diagram
• Created an ObjectContext

6. Programmatically access data by…
ADO.NET Entity Framework
• Custom DAO • Complete DAO
• T-SQL • LINQ

7. Agenda
Query

8. Real-World Problem #1 - Report
• Report for customer ‘Lynn’
• Sent orders
 # 54, #63, #57
• Partially sent orders
 #82: awaiting shoes, pants
 #92: awaiting gloves
• Unshipped orders
 #93 6 items
 #97 5 items

9. The Report T-SQL

10. Current Practices- Life without Entity Framework
Code Demo

11. Report with Entity Framework
Code Demo

12. Using EF – Writing a Query using LINQ

13. Compare Extracting Data

14. Mapping Relationships
Id Name Id Number Total Customerid
ADO
.Ne
t
Customer
Customer Id Invoice
Id Invoice Name Id
Name Id Number
Number EF Total
Total CustomerId
CustomerId

15. Report with Entity Framework
Code Demo - Continued

16. Smart Objects
Customer
GetShipped
GetUnshipped
GetPartiallyShiped
Invoice
IsShipped
IsUnshipped
IsPartiallyShiped

17. Looking at the T-SQL Generated by EF
• Use SQL Profiler
• Create a trace
• Filter for
Application:
• EntityFramework

18. The N+1 Problem
1 + 1 + 5 =7
Customer Customers Invoices Trips to
Invoices Items Database

19. More about Loading – Why Lazy Loading
• Lazy is Good and Easy, but
 Lazy isn’t always efficient
 Lazy is always correct
 Sometimes better to use selective eager loading
• Syntax – use .Include("invoices.invoiceItems”)
• More about – lazy loading - here

20. Constrained Eager Loading
Code Demo

21. Agenda
Save

22. Real-world Problem #2 – CRUD operations
Warehouse Process Load / Create
Report Shipment Customer
Load / Create Load / Create
Action
Invoice Item Invoice
Shipped
Cancelled
Remove Set Item
Item Shipped

23. Warehouse
Processing
Code Demo

24. Using EF – Adding Data using LINQ

25. With Entity Framework…
• Simplified/ Reduced data access code
 Save Encapsulates
 Delete
 Insert
 Update
 Key relationship
 Order of operations
 Transactions
• Prevents Most SQL Injection
 Sanitizes database inputs

26. SQL Injection and Entity Framework
“Little Bobby Tables”

27. Agenda
Patterns

28. Data Usage Patterns Load Model
Manipulate Model
Save Model
Common
Preferred

29. Modularity
Code Demo

30. Making Entity Framework Testable
Old Way New Way - Testable
DoSomething() DoSomething()
2)Get Data 2)Load Data
3)Manipulate Data 3)DoSomething(Data)
4)Render Data
Load()
2)Get Data
DoSomething(Data)
2)Manipulate Data
3)Render Data

31. Testing Loaders
Code Demo

32. Common Usage Pattern
MyProject.Views Load Model
MyProject.Controller
Manipulate Model
Save Model
MyProject.Business
MyProject.Rules
MyProject.Processes

33. Common Usage Pattern
MyProject.Views Load Model
MyProject.Controller
Manipulate Model
Save Model
MyProject.Business
MyProject.Rules
MyProject.Processes MyProject.Loaders

34. Stored Procedures
• Security
• Reduced Access
• Performance
• Modularity
• Containment
• Maintainability

35. Mapping Stored Procedures to EF Models

36. ORM to DB should be 1-1
• Complex mappings obscure the database
?
=

37. Existing Database Problems are
Amplified
• Primary Keys
• Wide Tables
• Bad Names
• Dead Columns

38. “Next Steps” for Attendees
• Use Entity Framework
 Write less CRUD code
 Protect against SQL Injection
 Master LINQ
• Use patterns / best practices with EF
 i.e. Loader pattern
 Modularity for testability (mocking)
• Map EF as closely as possible to the database
 Map 1-to-1
 Fix design issues at the database level first

39. More about learning LINQ – using Koans
• 28 progressive examples to help you learn LINQ
• LinqKoans.codeplex.com

40. Resources for Attendees
• EF team blog – here
• Julie Lehrman book - here
• Testing EF – video coming soon
 On ApprovalTests YouTube playlist - here
 www.ApprovalTests.com

41. Related Session(s)
http://www.devteach.com/Schedule.aspx
•SQL361 - Query Tuning Tips for SQL Server

42. TeachingKidsProgramming.org
Do a Recipe  Teach a Kid (Ages 10 ++)
SmallBasic or Java  Free Courseware (recipes)

43. Contact Information
@LlewellynFalco
www.ApprovalTests.com
@LynnLangit
www.LynnLangit.com