Book Image

Entity Framework Tutorial (Update) - Second Edition

By : Joydip Kanjilal
Book Image

Entity Framework Tutorial (Update) - Second Edition

By: Joydip Kanjilal

Overview of this book

The ADO.NET Entity Framework from Microsoft is a new ADO.NET development framework that provides a level of abstraction for data access strategies and solves the impedance mismatch issues that exist between different data models This book explores Microsoft’s Entity Framework and explains how it can used to build enterprise level applications. It will also teach you how you can work with RESTful Services and Google’s Protocol Buffers with Entity Framework and WCF. You will explore how to use Entity Framework with ASP.NET Web API and also how to consume the data exposed by Entity Framework from client applications of varying types, i.e., ASP.NET MVC, WPF and Silverlight. You will familiarize yourself with the new features and improvements introduced in Entity Framework including enhanced POCO support, template-based code generation, tooling consolidation and connection resiliency. By the end of the book, you will be able to successfully extend the new functionalities of Entity framework into your project.

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Entity Framework Tutorial (Update) - Second Edition
Joydip Kanjilal
Aug, 2015 | 274 pages
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Table of Contents (16 chapters)
Entity Framework Tutorial Second Edition
Entity Framework Tutorial Second Edition
Credits
Credits
About the Author
About the Author
About the Reviewers
About the Reviewers
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
Introducing the ADO.NET Entity Framework
Introducing the ADO.NET Entity Framework
What you should know
Looking back
What is the ADO.NET Entity Framework?
A comparative analysis of Entity Framework and other ORM tools
Entity Framework architectural components
System requirements
Performance improvements in Entity Framework 6
New features in Entity Framework 7
Summary
2
Getting Started
Getting Started
Designing the UserAuthentication database
Creating the EDM
The DataSource controls
Implementing our first application using the Entity Framework
Summary
3
Entities, Relationships, and the Entity Data Model
Entities, Relationships, and the Entity Data Model
Entities, entity types, and relationships in the EDM
Exploring the Security EDM
Summary
4
Working with Stored Procedures in the Entity Data Model
Working with Stored Procedures in the Entity Data Model
Creating a database using model-first development
Creating stored procedures
Mapping stored procedures to functions in the EDM
Executing stored procedures using the EDM
Mapping stored procedures that return custom entity types
Summary
5
Working with Entity Client and Entity SQL
Working with Entity Client and Entity SQL
An overview of the E-SQL language
From T-SQL to E-SQL
Why E-SQL when I already have LINQ to Entities?
Data paging using E-SQL
Working with the ADO.NET Entity Client
Other operations with E-SQL
Deferred, eager, and lazy loading
Summary
6
Working with LINQ to Entities
Working with LINQ to Entities
Introducing LINQ
Understanding the LINQ architecture
Parallel LINQ
Operators in LINQ
Querying data using LINQ
Summary
7
Working with the Object Services Layer
Working with the Object Services Layer
What are Object Services?
Performing CRUD operations on objects
Attaching and detaching objects to and from ObjectContext
Serializing and deserializing entity instances
Change tracking and identity resolution using ObjectContext
Understanding the code-first, model-first, and database-first approaches to domain design
Inheritance in Entity Framework
Implementing complex types in the EDM
State management, identity management, and relationship management
Reading objects from the Security database
Inserting objects from the Security database
Editing objects from the Security database
Deleting objects from the Security database
Summary
8
Working with WCF Data Services
Working with WCF Data Services
Introducing WCF Data Services
Exposing data as a service using WCF Data Services
Why do we need REST?
What is the OData Protocol?
Working with WCF Data Services and Entity Framework
Working with OData Services using WCF and ASP.NET MVC Framework
Working with Protobuf WCF Services
Summary
Advanced Concepts
Advanced Concepts
REST and REST-based service frameworks
HTTP methods, request, and response codes
Abbreviations
New features in Entity Framework 7
Suggested reading
Index
Index

Attaching and detaching objects to and from ObjectContext

You can use the Attach or Detach methods of the ObjectContext class to attach or detach objects. It should be noted that Attach will attach the entire object graph. The method cannot determine which objects are new and which already exist in ObjectContext. Note that when you execute a query on ObjectContext, the objects that are returned as a result of the query are attached in ObjectContext.

You can attach an object to ObjectContext by calling any of the following methods on ObjectContext:

  • Attach

  • AddObject

  • AttachTo

  • ApplyPropertyChanges

But what does Attach and Detach mean here? You use Attach to attach an object to the context. You should use Attach when the entity already exists in the database and you want the context to know about it without performing a query to locate the entity. When you attach an entity to ObjectContext using the Attach method, it sets EntityState of the object being attached to the Unchanged state. In...

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