book

Programming Entity Framework: DbContext

by Julia Lerman, Rowan Miller

February 2012

Intermediate to advanced

258 pages

6h 51m

English

O'Reilly Media, Inc.

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Programming Entity Framework: DbContext
Preface
AudienceContents of This BookConventions Used in This BookUsing Code ExamplesSafari® Books OnlineHow to Contact UsAcknowledgments
1. Introducing the DbContext API
Getting the DbContext API into Your ProjectLooking at Some Highlights of the DbContext APIReducing and Simplifying Ways to Work with a SetRetrieving an Entity Using ID with DbSet.FindAvoiding Trolling Around the Guts of Entity FrameworkWorking with the BreakAway ModelGetting the Sample SolutionGetting DbContext from an EDMX ModelEnsuring DbContext Instances Get Disposed
2. Querying with DbContext
Writing Queries with LINQ to EntitiesQuerying All the Data from a SetUsing LINQ for Sorting, Filtering, and MoreFinding a Single ObjectQuerying Local DataUsing the Load Method to Bring Data into MemoryRunning LINQ Queries Against LocalWorking with the ObservableCollection Returned by LocalLoading Related DataLazy LoadingUnderstanding the downsides of lazy loadingEager LoadingUnderstanding the downsides of eager loadingUsing Include in LINQ queriesExplicit LoadingChecking If a Navigation Property Has Been LoadedQuerying Contents of a Collection Navigation PropertyExplicit Loading a Subset of the Contents of a Navigation Property
3. Adding, Changing, and Deleting Entities
Working with Single EntitiesAdding New EntitiesChanging Existing EntitiesDeleting Existing EntitiesDeleting without loading from the databaseDeleting an object with related dataMultiple Changes at OnceThe “Find or Add” PatternWorking with RelationshipsAdding a Relationship Between ObjectsChanging a Relationship Between ObjectsRemoving a Relationship Between ObjectsWorking with Change TrackingUsing Snapshot Change TrackingUnderstanding When Automatic Change Detection OccursControlling When DetectChanges Is CalledUsing DetectChanges to Trigger Relationship Fix-upEnabling and Working with Change Tracking ProxiesEnsuring the New Instances Get ProxiesCreating Proxy Instances for Derived TypesFetching Entities Without Change Tracking
4. Working with Disconnected Entities Including N-Tier Applications
A Simple Operation on a Disconnected GraphExploring the Challenges of N-TierUsing Existing N-Tier Frameworks That Support Graph ModificationUsing Explicit Operations on the Server SideReplaying Changes on the ServerUnderstanding How DbContext Responds to Setting the State of a Single EntityMarking a New Entity as AddedMarking an Existing Entity as UnchangedMarking an Existing Entity as ModifiedRegistering an Existing Entity for DeletionUsing a stub entity to mark for deletionWorking with Relationships with and Without Foreign KeysBenefiting from foreign key propertiesUsing navigation properties to define relationshipsSetting the State for Multiple Entities in an Entity GraphGetting the Graph into the ContextSetting the State of Entities in a GraphBuilding a Generic Approach to Track State LocallyCreating a Generic Method That Can Apply State Through Any GraphConcurrency ImplicationsTracking Individually Modified PropertiesRecording Modified Property NamesConcurrency implicationsRecording Original ValuesConcurrency implicationsQuerying and Applying ChangesConcurrency implications
5. Change Tracker API
Change Tracking Information and Operations for a Single EntityWorking with the State PropertyWorking with Current, Original, and Database ValuesWorking with DbPropertyValues for Complex TypesCopying the Values from DbPropertyValues into an EntityChanging Values in a DbPropertyValuesUsing the SetValues methodWorking with Individual PropertiesWorking with Scalar PropertiesWorking with Complex PropertiesWorking with Navigation PropertiesModifying the value of a navigation propertyModifying navigation properties with the change trackerWorking with collection navigation propertiesRefreshing an Entity from the DatabaseChange Tracking Information and Operations for Multiple EntitiesUsing the Change Tracker API in Application ScenariosResolving Concurrency ConflictsLogging During Save Changes
6. Validating with the Validation API
Defining and Triggering Validation: An OverviewValidating a Single Object on Demand with GetValidationResultSpecifying Property Rules with ValidationAttribute Data AnnotationsValidating Facets Configured with the Fluent APIValidating Unmapped or “Transient” PropertiesValidating Complex TypesUsing Data Annotations with an EDMX ModelInspecting Validation Result DetailsInspecting Individual Validation ErrorsExploring More ValidationAttributesUsing CustomValidationAttributesValidating Individual Properties on DemandSpecifying Type-Level Validation RulesUsing IValidatableObject for Type ValidationValidating Multiple Rules in IValidatableObjectUsing CustomValidationAttributes for Type ValidationUnderstanding How EF Combines ValidationsValidating Multiple ObjectsValidating When Saving ChangesReviewing ObjectContext. SaveChanges WorkflowUnderstanding DbContext.SaveChanges WorkflowDisabling Validate Before Save
7. Customizing Validations
Overriding ValidateEntity in the DbContextConsidering Different Ways to Leverage ValidateEntityUpdating Data During SaveChangesOverriding SaveChanges When Validation OccursComparing ValidateEntity to SaveChanges for Custom LogicUsing the IDictionary Parameter of ValidateEntityControlling Which Entities Are Validated in ValidateEntity
8. Using DbContext in Advanced Scenarios
Moving Between ObjectContext and DbContextAccessing ObjectContext Features from a DbContextAdding DbContext into Existing .NET 4 ApplicationsLeveraging SQL Server Operators Exposed in SqlFunctionsQuerying Derived Types with DbSetUnderstanding the Interface Property LimitationConsidering Automated Testing with DbContextTesting with DbSetExploring a Scenario That Unnecessarily Queries the DatabaseReducing Database Hits in Testing with IDbSetCreating an IDbSet ImplementationAbstracting BreakAwayContext for TestsReviewing the ImplementationSupplying Data to a FakeDbSetAccessing the Database Directly from DbContextExecuting Queries with Database.SqlQuery and DbSet.SqlQueryTracking Results of SqlQueryExecuting Commands from the Database ClassProviding Multiple Targeted Contexts in Your ApplicationReusing Classes, Configurations, and Validation Across Multiple ContextsEnsuring That All DbContexts Use a Single DatabaseValidating Relationship Constraints and Other Validations with Multiple ContextsGetting Code First to Create Full BreakAwayContext Database

9. What’s Coming Next for Entity Framework
Understanding Entity Framework’s Version NumbersEntity Framework 5.0EnumsSpatial DataPerformance ImprovementsMultiple Result Sets from Stored ProceduresTable Value Functions
About the Authors
Copyright

Content preview from Programming Entity Framework: DbContext

Programming Entity Framework: DbContext

Julia Lerman

Rowan Miller

Beijing • Cambridge • Farnham • Köln • Sebastopol • Tokyo

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Programming Entity Framework: DbContext

by Julia Lerman, Rowan Miller