Pro LINQ: Language Integrated Query in C# 2010

818 Pages·2010·14.311 MB·

by  Adam Freeman, Joseph C. Rattz Jr. (auth.)

Pro LINQ
Language Integrated Query in C#
2010

■ ■ ■

Adam Freeman and Joseph C. Rattz, Jr.
■ CONTENTS

Pro LINQ: Language Integrated Query in C# 2010
Copyright © 2010 by Adam Freeman and Joseph C. Rattz, Jr.
All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means,
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Dedicated to my wife, Jacqui Griffyth
—Adam Freeman

For my parents, Joe and Josie Rattz, that believed I could do anything and encouraged me to
believe the same. Thank you.
—Joseph C. Rattz, Jr.
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Contents at a Glance
Contents at a Glance ..........................................................................iv
Contents ...........................................................................................vi
About the Author............................................................................... xx
About the Technical Reviewer ........................................................... xxi
Acknowledgments........................................................................... xxii
Part 1: Pro LINQ: Language Integrated Query in C# 2010.........................1
■Chapter 1: Hello LINQ .......................................................................3
■Chapter 2: C# Language Enhancements for LINQ ...............................21
Part 2: LINQ to Objects ......................................................................55
■Chapter 3: LINQ to Objects Introduction............................................57
■Chapter 4: Deferred Operators.........................................................69
■Chapter 5: Nondeferred Operators.................................................. 151
Part 3: LINQ to XML......................................................................... 211
■Chapter 6: LINQ to XML Introduction .............................................. 213
■Chapter 7: The LINQ to XML API ..................................................... 219
■Chapter 8: LINQ to XML Operators.................................................. 313
■Chapter 9: Additional XML Capabilities........................................... 345
Part 4: LINQ to DataSet.................................................................... 387
■Chapter 10: LINQ to DataSet Operators........................................... 389
■Chapter 11: Additional DataSet Capabilities.................................... 427
Part 5: LINQ to SQL ...........................................................................55
■Chapter 12: LINQ to SQL Introduction ............................................. 437
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■Chapter 13: LINQ to SQL Tips and Tools.......................................... 449
■Chapter 14: LINQ to SQL Database Operations................................. 475
■Chapter 15: LINQ to SQL Entity Classes .......................................... 521
■Chapter 16: The LINQ to SQL DataContext ....................................... 569
■Chapter 17: LINQ to SQL Concurrency Conflicts............................... 635
■Chapter 18: Additional LINQ to SQL Capabilities .............................. 653
Part 6: LINQ to Entities.................................................................... 665
■Chapter 19: LINQ to Entities Introduction........................................ 667
■Chapter 20: LINQ to Entities Operations.......................................... 679
■Chapter 21: LINQ to Entities Classes .............................................. 723
Part 7: Parallel LINQ..........................................................................55
■Chapter 22: Parallel LINQ Introduction ........................................... 751
■Chapter 23: Using Parallel LINQ..................................................... 757
■Chapter 24: Parallel LINQ Operators............................................... 773
Index ............................................................................................. 795
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Contents
Contents at a Glance ..........................................................................iv
Contents ...........................................................................................vi
About the Author............................................................................... xx
About the Technical Reviewer ........................................................... xxi
Acknowledgments........................................................................... xxii
Part 1: Pro LINQ: Language Integrated Query in C# 2010.........................1
■Chapter 1: Hello LINQ .......................................................................3
A Paradigm Shift.............................................................................................................3
Query XML.............................................................................................................................................4
Query a SQL Server Database................................................................................................................5
Introduction.....................................................................................................................7
LINQ Is About Data Queries....................................................................................................................7
How to Obtain LINQ................................................................................................................................8
LINQ Is Not Just for Queries............................................................................................8
Tips to Get You Started.................................................................................................12
Use the var Keyword When Confused..................................................................................................12
Use the Cast or OfType Operators for Legacy Collections.....................................................................................14
The OfType Operator versus the Cast Operator...................................................................................15
Don’t Assume a Query Is Bug-Free......................................................................................................15
Take Advantage of Deferred Queries...................................................................................................16
Use the DataContext Log.....................................................................................................................17
Use the LINQ Forum.............................................................................................................................18
Summary......................................................................................................................18
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■Chapter 2: C# Language Enhancements for LINQ ...............................21
C# Language Additions.................................................................................................21
Lambda Expressions..............................................................................................................................................22
Expression Trees...................................................................................................................................................27
Keyword var, Object Initialization, and Anonymous Types....................................................................................28
Extension Methods................................................................................................................................................33
Partial Methods.....................................................................................................................................................39
Query Expressions.................................................................................................................................................41
Summary......................................................................................................................52
Part 2: LINQ to Objects ......................................................................55
■Chapter 3: LINQ to Objects Introduction............................................57
LINQ to Objects Overview.............................................................................................57
IEnumerable<T>, Sequences, and the Standard Query Operators...............................58
Returning IEnumerable<T>, Yielding, and Deferred Queries.......................................59
Func Delegates.............................................................................................................62
The Standard Query Operators Alphabetical Cross-Reference.....................................64
A Tale of Two Syntaxes.................................................................................................66
Summary......................................................................................................................66
■Chapter 4: Deferred Operators.........................................................69
Referenced Namespaces..............................................................................................69
Referenced Assemblies................................................................................................69
Common Classes..........................................................................................................69
The Deferred Operators by Purpose.............................................................................71
Restriction...........................................................................................................................................71
Projection.............................................................................................................................................74
Partitioning..........................................................................................................................................85
Concatenation........................................................................................................................................................93
Ordering.................................................................................................................................................................96
Join......................................................................................................................................................................116
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Grouping..............................................................................................................................................................120
Set.......................................................................................................................................................................126
Conversion.........................................................................................................................................133
Element..............................................................................................................................................140
Generation.........................................................................................................................................145
Summary....................................................................................................................148
■Chapter 5: Nondeferred Operators.................................................. 151
Referenced Namespaces............................................................................................151
Common Classes........................................................................................................151
The Nondeferred Operators by Purpose.....................................................................154
Conversion...........................................................................................................................................................155
Equality................................................................................................................................................................168
Element................................................................................................................................................................172
Quantifiers...........................................................................................................................................................187
Aggregate............................................................................................................................................................193
Summary....................................................................................................................209
Part 3: LINQ to XML......................................................................... 211
■Chapter 6: LINQ to XML Introduction .............................................. 213
Introduction.................................................................................................................215
Cheating the W3C DOM XML API.................................................................................216
Summary....................................................................................................................217
■Chapter 7: The LINQ to XML API ..................................................... 219
Referenced Namespaces............................................................................................219
Significant API Design Enhancements........................................................................219
XML Tree Construction Simplified with Functional Construction......................................................220
Document Centricity Eliminated in Favor of Element Centricity........................................................222
Names, Namespaces, and Prefixes...................................................................................................224
Node Value Extraction.......................................................................................................................227
The LINQ to XML Object Model...................................................................................230
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Deferred Query Execution, Node Removal, and the Halloween Problem....................231
XML Creation..............................................................................................................234
Creating Elements with XElement.....................................................................................................234
Creating Attributes with XAttribute....................................................................................................237
Creating Comments with XComment.................................................................................................238
Creating Containers with XContainer.................................................................................................238
Creating Declarations with XDeclaration...........................................................................................239
Creating Document Types with XDocumentType...............................................................................240
Creating Documents with XDocument.................................................................................................................241
Creating Names with XName.............................................................................................................242
Creating Namespaces with XNamespace..........................................................................................243
Creating Nodes with XNode.................................................................................................................................243
Creating Processing Instructions with XProcessingInstruction.........................................................243
Creating Streaming Elements with XStreamingElement...................................................................246
Creating Text with XText....................................................................................................................247
Creating CData with XCData................................................................................................................................248
XML Output.................................................................................................................248
Saving with XDocument.Save()..........................................................................................................248
Saving with XElement.Save()...............................................................................................................................250
XML Input....................................................................................................................251
Loading with XDocument.Load()........................................................................................................251
Loading with XElement.Load()...........................................................................................................253
Parsing with XDocument.Parse() or XElement.Parse()......................................................................254
XML Traversal.............................................................................................................254
Traversal Properties..........................................................................................................................255
Traversal Methods.............................................................................................................................260
XML Modification........................................................................................................276
Adding Nodes......................................................................................................................................................276
Deleting Nodes..................................................................................................................................281
Updating Nodes.................................................................................................................................284
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XElement.SetElementValue() on Child XElement Objects..................................................................289
XML Attributes............................................................................................................290
Attribute Creation................................................................................................................................................291
Attribute Traversal.............................................................................................................................291
Attribute Modification........................................................................................................................295
XML Annotations.........................................................................................................300
Adding Annotations with XObject.AddAnnotation()............................................................................300
Accessing Annotations with XObject.Annotation() or XObject.Annotations().......................................................300
Removing Annotations with XObject.RemoveAnnotations()................................................................................301
Annotations Example...........................................................................................................................................301
XML Events.................................................................................................................304
XObject.Changing..............................................................................................................................305
XObject.Changed...............................................................................................................................305
A Couple of Event Examples..............................................................................................................306
Trick or Treat, or Undefined?.............................................................................................................310
Summary....................................................................................................................310
■Chapter 8: LINQ to XML Operators.................................................. 313
Introduction to LINQ to XML Operators.......................................................................313
Ancestors....................................................................................................................314
Prototypes............................................................................................................................................................314
Examples...........................................................................................................................................314
AncestorsAndSelf.......................................................................................................319
Prototypes............................................................................................................................................................319
Examples...........................................................................................................................................319
Attributes....................................................................................................................322
Prototypes............................................................................................................................................................322
Examples...........................................................................................................................................322
DescendantNodes.......................................................................................................324
Prototypes............................................................................................................................................................324
Examples...........................................................................................................................................325
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