geeks track 2 - ado.net and entity framework best practices - andri yadi

8/9/2019 Geeks Track 2 - ADO.net and Entity Framework Best Practices - Andri Yadi

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ENTITY FRAMEWORK V2BEST PRACTICES

, ,Microsoft Innovation Day 2010 May 11 2010

ndri Yadi .| a@dycode com, ,CEO DyCode | MVP VSTO


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:// . / /http itunes com apps movreak


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Entity FrameworkEntity Framework

SQL Server 2008

WCF Data Services WCF Data Services/HTTP REST

JSONSON

-Real world Scenario


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. .Dr EF Codd


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DELETEDELETE

SELECTSELECT

COUNTCOUNT

LEFTLEFTUNIONUNION /MIN MAX/MIN MAX

JOINJOIN

HAVINGHAVINGORDER BYORDER BY

RIGHTRIGHT

INSERTINSERT

WHEREWHERE

UPDATEUPDATE

Then we code in SQL

Then we code in SQL


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;SqlCommand oCmd;SqlDataReader oDR

= .string connString ConfigurationManager

[" "].ConnectionStrings OracleConnString;ConnectionString

=SqlConnection conn new( );SqlConnection connString

;string selectQuery

= ;int _returnValue 0

= ( ) selectQuery SELECT COUNT OrderID from Orders+ = ;where EmployeeID @EmpID

. ();conn Open= ( , );oCmd new SqlCommand selectQuery conn. . ( , . );oCmd Parameters Add @EmpID SqlDbType Int. [ ]. = ;oCmd Parameters @EmpID Value employeeID= . ();oDR oCmd ExecuteReader

( . ())if oDR Read= . ( );_returnValue oDR GetInt32 0

. ();oDR Close. ();conn Close

.ADO NET code


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The Dilemma


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.ADO NETADO( )1996

DAO( )1992

RDO


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! !Enough We need ORM


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O

bjectR elationalMapping

Technique for working withrelational tables as if

they were objects in memory Hide away the complexity of

the underlying tables andgive a uniform way of

working with data


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Why ORM? Development productivity Database independence Database portability


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Many attempts

Typed Datasets Objectspaces v1 Objectspaces v2 Microsoft BusinessFramework WinFS

Linq to SQL NHibernate Will RIP Not Microsoft s


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.ADO NET EntityFramework

Microsoft s strategictechnology

Used in other Microsoft(technologies reporting

)services . .V2 released with NET 4 0


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Entity DataModel

,Invented in the 1970s by.Dr Peter Chen

ERM

Conceptual Layer Mapping Layer

Storage Layer

: .Now EDM in ADO NETEntity Framework


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Entity Framework vs LinqToSQL


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ET S GO DEEPER ON EF2


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EDM


Conceptual ModelConceptual Model


< >IEnumerable T

EntityDataReader

LINQ to EntitiesEntity SQL Query

Command TreeEntity SQL Query


EntityDataReaderCommand TreeStorage ModelStorage Model

Mapping


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DEMO-Model first


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Eager Loading

Structure the initial queryin such a way that all ofthe required objects are

returned in the initialquery

from c in.nw Customers. (" ")nclude Orders

;select c


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Explicit Loading

Explicitly request to load

the related objects . . ();customer Orders Load


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Lazy Loading

Related objects are loadedautomatically for you whenyou access them


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POCO Support

Plain Old CLR Object User your own POCO objects

with no EF attributes Code your POCO classes Code Entity Framework

Context

Or use T4 POCO entitygenerator by VS2010


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Questions onPOCO

Do I still need an EDM? Yes How is metadata mapped to

POCO entities?onvention basedmapping , ,Entity Type Property and

Complex Types names mustmatch those defined by in

EDM

/Is deferred lazy loadingsupported? Yes


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Lazy Loading onPOCO

-Declare lazy loaded propertyas virtual

Make sure to enable.ContextOptions LazyLoadingEnabled

What s under the hood?


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POCO Changetracking

-Snapshot based -Proxy based


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DEMOPOCO


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DEMO Generate EDM from database


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&Performancesecurity?

Connections to database

.vs amount of data You can work with stored

procedures You can work with views You can define how the

.ADO NET Entity Frameworkloads your data to

Eager Lazy ( )Explicit


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F V2 IN DISTRIBUTED SYSTEM


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SQL Server 2008

A WCF ServiceA WCF Service

Distributed system WCF service

Pr

oxy

Pr

oxy

Da

ta

Bi

ndi

ng

Da

ta

Bi

ndi

ng

ObjectContextavailable

ObjectContext notavailable


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SQL Server 2008

WCF Data Service WCF Data Service/HTTP REST

Distributed system WCF Dataservice

/HTTP REST

Da

ta

Se

rv

ice

Co

nt

ext

Da

ta

Se

rv

ice

Co

nt

ex

t

Da

ta

Bi

ndi

ng

Da

ta

Bi

ndi

ng

ObjectContextavailable

ObjectContext notavailable

/SON/SONXMLML


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, O WHAT S NEW IN EF2?


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Entityenhancements

-Foreign keys supported inthe conceptual model

Testability enhancements < >IObjectSet T and

< >ObjectSet T Easier to mock data

context and dataentities for tests

Lazy loading for relatedobjects Options now for explicit

or implicit loading


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Support forpersistence

ignorant objects

Persistence ignorant objects POCO objects with no EF

, .attributes etc Mapped to conceptual modelvia convention

Change tracking possiblewith generated proxies or

snapshot

-Managing types in n tierapplications /Easier to add attach objects

to a context More control over object

state

Issues you should consider You still need the Entity( )Data Model edmx To use objects with WCF

useProxyDataContractResolver


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Designerenhancements

Support for complex types &Singularization

pluralization

Model first development Creates DDL for database

based on your model

Designer extensibility Influence the EDMX

generation

Add visuals Influence DDL creation


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Code generationcustomization

Based on T4 templates Included as of VS 2008 ,Runtime support but not

much design support

T4 and Entity Framework T4 used to generate code

from model Create new T4 templates

to use instead

Add validation logic Create POCO objects


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References

. ADO NET team blog keep up withnew features in Entity

framework

:// . . /http blogs msdn com adonet

. #ADO NET C POCO Entity Generator . #DO NET C Web Site POCO Entity WCF Data Services team blog

:// . . /http blogs msdn com astoriateam
http://visualstudiogallery.msdn.microsoft.com/en-us/23df0450-5677-4926-96cc-173d02752313http://visualstudiogallery.msdn.microsoft.com/en-us/23df0450-5677-4926-96cc-173d02752313http://visualstudiogallery.msdn.microsoft.com/en-us/fe568da5-aa1a-4178-a2a5-48813c707a7fhttp://visualstudiogallery.msdn.microsoft.com/en-us/fe568da5-aa1a-4178-a2a5-48813c707a7fhttp://visualstudiogallery.msdn.microsoft.com/en-us/fe568da5-aa1a-4178-a2a5-48813c707a7fhttp://visualstudiogallery.msdn.microsoft.com/en-us/23df0450-5677-4926-96cc-173d02752313


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DyCode. . .www dycode com | office@dycode comDynamic IT Solutions for Optimal Business

Value

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