entity framework 4
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EF4 through POCO
11.02.2010
Marjan Nikolovski
Agenda
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• Introduction• Installation• Getting started• Loading entity properties• Tracking changes• Working with proxy enabled data• Serialization of proxy objects for WCF usage• Technology performance• Pros and Cons
Introduction
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• Yet Another ORM tool ?• Custom classes as data proxy• POCO acronym• Before and Now
Yet Another ORM tool ?
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• How it is different from the previous known• POCO vs. nHybernate, nHydrate, LINQ-SQL
Date: 11.02.2010Author: Marjan Nikolovski
POCO nHybernate
nHydrate LINK-SQL
portable
easy extensible
visual mapper
mature
Support LINQ
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POCO acronym
• Plain Old CLR Object• Acronym for non-persistant data (persistant ignorant)
Date: 11.02.2010Author: Marjan Nikolovski
Before
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• Unreadable code• Bad programming style• Almost no extensible designs• Lot of bugs• Knotted logic
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• Forgotten CRUD principles• Security issues
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Before
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• Unclear DDL/BLL logic
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Before
EF4 POCO now offers you:
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• Efficiency
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• Easy DB switching
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EF4 POCO now offers you:
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• Less time getting nervous with debugging queries.
Date: 11.02.2010Author: Marjan Nikolovski
EF4 POCO now offers you:
Installation
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• Visual Studio 2010 beta 2• ADO.NET Entity Framework Feature Community
Technology Preview 2
Date: 11.02.2010Author: Marjan Nikolovski
Getting started
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• Mapping requirements• DB mapping and POCO class generation• POCO code generator• Classes handcrafting
• Data model to physical model
Date: 11.02.2010Author: Marjan Nikolovski
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Mapping requirementsGetting started
• Custom data class must not be non inheritable, abstract or private • Custom data class must have a public parameter less constructor • For lazy loading custom data class navigational properties must be
defined as overrideable (virtual).• Classes must not have any mapping attributes and must not
implement IEntityWithChangeTracker or IEntityWithRelationships interfaces.
• ProxyCreationEnabled in the ObjectContext’s ContextOptions must be set to true (default is true) for ObjectContext tracking.
Date: 11.02.2010Author: Marjan Nikolovski
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Mapping requirementsDB mapping and POCO class generation• Add Entity Model• Mapping DB to Model
Date: 11.02.2010Author: Marjan Nikolovski
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Mapping requirementsDB mapping and POCO class generationRemove custom tool
Date: 11.02.2010Author: Marjan Nikolovski
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Mapping requirementsDB mapping and POCO class generationClasses handcrafting
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Mapping requirementsDB mapping and POCO class generationClasses handcraftingCreate DB Context
Date: 11.02.2010Author: Marjan Nikolovski
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Mapping requirementsDB mapping and POCO class generationClasses handcraftingIn practice
Date: 11.02.2010Author: Marjan Nikolovski
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Mapping requirementsData model to physical model• Same protocol used descripted above only bottom
up strategy used• Create sql script
Date: 11.02.2010Author: Marjan Nikolovski
Loading entity navigational properties
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• Navigational properties• Explicit loading• Lazy loading• Eager loading
Date: 11.02.2010Author: Marjan Nikolovski
Loading entity navigational propertiesExplicit loading
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Date: 11.02.2010Author: Marjan Nikolovski
Lazy loading property in Object Context class must be set to false
Loading entity navigational propertiesLazy loading
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Date: 11.02.2010Author: Marjan Nikolovski
Lazy loading property in Object Context class must be set to truein order set auto navigation data loading
Loading entity navigational propertiesEager loading
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Date: 11.02.2010Author: Marjan Nikolovski
Eager loading is done by calling include method in LINQ query
Tracking changes
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• Proxy enabled mapping• Sharpshooting (self organized tracking)
Date: 11.02.2010Author: Marjan Nikolovski
Tracking changesProxy enabled mapping
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• Automatic tracking of changes in the Context
Date: 11.02.2010Author: Marjan Nikolovski
Tracking changesSharpshooting (self organized tracking)
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• Manual tracking of changes in the Context
Date: 11.02.2010Author: Marjan Nikolovski
Working with proxy enabled data
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• Enabling proxy enabled mapping and data manipulation
Date: 11.02.2010Author: Marjan Nikolovski
Working with proxy enabled dataEnabling proxy enabled mapping and data creation
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• ProxyCreationEnable property must be set to true• Creation of entity as proxy types
Date: 11.02.2010Author: Marjan Nikolovski
Serialization of proxy objects for WCF usage
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• What has to be done ?• One side implementation
Date: 11.02.2010Author: Marjan Nikolovski
Serialization of proxy objects for WCF usageWhat has to be done ?
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• Proxy object are objects of not known type• Defining service behavior where DataContractSerializer must be set
in order proxy data to be resolved to known type
Date: 11.02.2010Author: Marjan Nikolovski
Serialization of proxy objects for WCF usageOne side implementation
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Date: 11.02.2010Author: Marjan Nikolovski
Technology performance
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Date: 11.02.2010Author: Marjan Nikolovski
Pros and Cons
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• Object simplicity and great extensibility• Speeding up DAL design and implementation• Manual context synchronization can be tricky when comes to
business logic• Class construction overhead and memory overflow may occur when
no proper handling is used
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Q&A
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References
• http://thedatafarm.com/blog/data-access/agile-entity-framework-4-repository-part-1-model-and-poco-classes/
• http://www.code-magazine.com/Article.aspx?quickid=0909081• http://byatool.com/tag/entity-framework/• http://msdn.microsoft.com/en-us/magazine/ee236639.aspx• http://blogs.msdn.com/adonet/pages/feature-ctp-walkthrough-self-tracking-entities-for-the-entity-
framework.aspx• http://blogs.msdn.com/adonet/pages/feature-ctp-walkthrough-poco-templates-for-the-entity-
framework.aspx• http://blogs.msdn.com/adonet/archive/2009/05/21/poco-in-the-entity-framework-part-1-the-
experience.aspx• http://blogs.msdn.com/adonet/archive/2009/06/10/poco-in-the-entity-framework-part-3-change-
tracking-with-poco.aspx• http://blogs.msdn.com/adonet/archive/2009/05/19/sneak-peek-using-code-generation-templates-
with-the-entity--framework-4-0.aspx• http://blogger.forgottenskies.com/?p=518• http://msdn.microsoft.com/en-us/magazine/ee335715.aspx• http://blogs.msdn.com/efdesign/
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