List of Listings

Chapter 1: LINQ Introduction

Listing 1-1: Type declarations with simple relationships

Listing 1-2: Type declarations with two-way relationships

Listing 1-3: Class declaration mapped on a database table

Listing 1-4: Database update calling the SubmitChanges method

Listing 1-5: A fragment of an XML file of orders

Listing 1-6: Reading the XML file of orders using an XmlReader

Listing 1-7: Reading the XML file using LINQ to XML

Listing 1-8: Reading the XML file using LINQ to XML and Visual Basic 9.0 syntax

Listing 1-9: Creating the XML of orders using Visual Basic 9.0 XML literals

Listing 1-10: C# code equivalent to a LINQ query over Reflection

Listing 1-11: LINQ query that gets temporary files greater than 10,000 bytes, ordered by size

Chapter 2: C# Language Features

Listing 2-1: Delegate declaration

Listing 2-2: Delegate instantiation (C# 1.x)

Listing 2-3: Delegate instantiation (C# 2.0)

Listing 2-4: Common use for a delegate

Listing 2-5: Using an anonymous method

Listing 2-6: Parameters for an anonymous method

Listing 2-7: IEnumerator and IEnumerable declarations

Listing 2-8: Enumerable class

Listing 2-9: Sample enumeration code

Listing 2-10: Enumeration using a foreach statement

Listing 2-11: Enumeration using a yield statement

Listing 2-12: Multiple yield statements

Listing 2-13: Enumeration using yield (typed)

Listing 2-14: Explicitly typed parameter list

Listing 2-15: Implicitly typed parameter list

Listing 2-16: Expression body

Listing 2-17: Lambda expression examples

Listing 2-18: Lambda expression as a predicate

Listing 2-19: Use of an expression tree

Listing 2-20: Extension methods declaration

Listing 2-21: Extension methods for native value types

Listing 2-22: Extension methods call order

Listing 2-23: Extension methods overload

Listing 2-24: Instance method over extension methods

Listing 2-25: Extension methods resolution

Listing 2-26: Lambda expression as predicate

Listing 2-27: Standard syntax for object initialization

Listing 2-28: Object initializer

Listing 2-29: Explicit constructor call in object initializer

Listing 2-30: Nested object initializers

Listing 2-31: Initializers for owned objects

Listing 2-32: Collection initializers

Listing 2-33: Anonymous types definition

Listing 2-34: Implicitly typed arrays

Chapter 3: Visual Basic 9.0 Language Features

Listing 3-1: Nullable type declarations

Listing 3-2: Nullable type conversions

Listing 3-3: Local type inference

Listing 3-4: Changed behavior from Visual Basic 8.0 to Visual Basic 9.0

Listing 3-5: Standard method declaration and use

Listing 3-6: Extension method declaration

Listing 3-7: Extension method use

Listing 3-8: Sample class for object initializers

Listing 3-9: Initialization using With statement

Listing 3-10: Object initializer syntax

Listing 3-11: Object initializer syntax on multiple lines

Listing 3-12: Object initializer syntax and local type inference

Listing 3-13: Object initializers using expressions

Listing 3-14: Nested object initializers

Listing 3-15: Anonymous type definition

Listing 3-16: Array of anonymous types

Listing 3-17: Simple LINQ query

Listing 3-18: Order By in C# 3.0

Listing 3-19: Order By in Visual Basic 9.0

Listing 3-20: Lambda expressions in Visual Basic 9.0

Listing 3-21: Use of lambda expressions in query expressions

Listing 3-22: Closures with query expressions

Listing 3-23: XML literal used as a constant

Listing 3-24: Invalid XML literals

Listing 3-25: XML literal in a dynamic expression

Listing 3-26: Dynamic XML tags in an XML literal

Listing 3-27: Dynamic XML tags in explicit method calls

Listing 3-28: Closing tag for dynamic XML tags

Listing 3-29: Nested list of XML literals

Listing 3-30: Query embedded into an XML literal

Listing 3-31: Child axis

Listing 3-32: Attribute axis

Listing 3-33: Descendants axis

Listing 3-34: Relaxed delegates

Listing 3-35: Relaxed delegates with signature inference

Chapter 4: LINQ Syntax Fundamentals

Listing 4-1: A simple LINQ query

Listing 4-2: The first LINQ query translated into basic elements

Listing 4-3: A query with a restriction

Listing 4-4: A query with a restriction and an index-based filter

Listing 4-5: A query with a paging restriction

Listing 4-6: The list of orders made by Italian customers

Listing 4-7: The flattened list of orders made by Italian customers

Listing 4-8: The flattened list of orders made by Italian customers, written with a query expression

Listing 4-9: The list of Quantity and IdProduct of orders made by Italian customers

Listing 4-10: The list of Quantity and IdProduct of orders made by Italian customers, written with a query expression

Listing 4-11: A query expression with a descending orderby clause

Listing 4-12: A query expression with orderby and thenby

Listing 4-13: A custom comparer used with an OrderBy operator

Listing 4-14: The Reverse operator applied

Listing 4-15: The Reverse operator applied to a query expression with orderby and thenby

Listing 4-16: The GroupBy operator used to group customers by Country

Listing 4-17: A query expression with a group by syntax

Listing 4-18: The GroupBy operator used to group customer names by Country

Listing 4-19: The Join operator used to map orders with products

Listing 4-20: The Join operator query expression syntax

Listing 4-21: The GroupJoin operator used to map products with orders, if present

Listing 4-22: A query expression with a join into clause

Listing 4-23: The query expression of Listing 4-22 in its compact version

Listing 4-24: The Distinct operator applied to the list of products used in orders

Listing 4-25: The Distinct operator applied to a query expression

Listing 4-26: The Union operator applied to the second and third customer orders

Listing 4-27: The Intersect and Except operators applied to the second and third customer orders

Listing 4-28: Set operators applied to query expressions

Listing 4-29: The Count operator applied to customer orders

Listing 4-30: The Sum operator applied to customer orders

Listing 4-31: The Sum operator applied to customer orders, with a nested query

Listing 4-32: The Min operator applied to order quantities

Listing 4-33: The Min operator applied to wrong types (thereby throwing an ArgumentException)

Listing 4-34: The Max operator applied to custom types, with a value selector

Listing 4-35: Both Average operator signatures applied to product prices

Listing 4-36: Customers and their average order amounts

Listing 4-37: Customers and their most expensive orders

Listing 4-38: Products and their ordered amounts

Listing 4-39: Customers and their most expensive orders paired with the month of execution

Listing 4-40: A set of years generated by the Range operator, used to filter orders

Listing 4-41: A factorial of a number using the Range operator

Listing 4-42: The Repeat operator, used to repeat the same query many times

Listing 4-43: The Empty operator used to initialize an empty set of customers

Listing 4-44: The Any operator applied to all customer orders to check orders of IdProduct == 1

Listing 4-45: The All operator applied to all customer orders to check the quantity

Listing 4-46: The Contains operator applied to the first customer’s orders

Listing 4-47: The Take operator, applied to extract the two top customers ordered by order amount

Listing 4-48: The TakeWhile operator, applied to extract the top customers that form 80 percent of all orders

Listing 4-49: The First operator, used to select the first American customer

Listing 4-50: Examples of the FirstOrDefault operator syntax

Listing 4-51: Examples of the Single operator syntax

Listing 4-52: Examples of the ElementAt and ElementAtOrDefault operator syntax

Listing 4-53: Example of the DefaultIfEmpty operator syntax, both with default(T) and a custom default value

Listing 4-54: The Concat operator, used to concatenate Italian customers with customers from the United States

Listing 4-55: Example that shows when expression trees are evaluated

Listing 4-56: A query expression over a custom list of type Customers

Listing 4-57: A query expression over a list of Customers converted with the AsEnumerable operator

Listing 4-58: A query expression over an immutable list of Customers obtained by the ToList operator

Listing 4-59: A query expression that uses ToList to copy the result of a query over products

Listing 4-60: An example of the ToDictionary operator, applied to customers

Listing 4-61: An example of the ToLookup operator, used to group orders by product

Chapter 5: LINQ to ADO.NET

Listing 5-1: Entity definition for LINQ to SQL

Listing 5-2: Simple LINQ to SQL query

Listing 5-3: Hierarchy of classes based on contacts

Listing 5-4: Queries using a hierarchy of entity classes

Listing 5-5: Object identity

Listing 5-6: Association EntityRef

Listing 5-7: Association EntitySet (visible)

Listing 5-8: Association EntitySet (hidden)

Listing 5-9: Use of DataShape and LoadWith<T>

Listing 5-10: Use of DataShape and AssociateWith<T>

Listing 5-11: Query manipulation

Listing 5-12: Stored procedure declaration

Listing 5-13: Stored procedure with multiple results

Listing 5-14: Scalar-valued user-defined function

Listing 5-15: Table-valued user-defined function

Listing 5-16: Compiled query in a local scope

Listing 5-17: Compiled query assigned to a static member

Listing 5-18: Query with Join

Listing 5-19: Query using Association

Listing 5-20: Access through Entity

Listing 5-21: Access through Entity with a single statement

Listing 5-22: Direct query

Listing 5-23: Submit changes to the database

Listing 5-24: Retry loop for a concurrency conflict

Listing 5-25: Transaction controlled by TransactionScope

Listing 5-26: Stored procedure to override an update

Listing 5-27: Loading DataSet using a DataAdapter

Listing 5-28: Querying a DataTable with LINQ

Listing 5-29: Joining two DataTable objects with LINQ

Listing 5-30: Leveraging DataSet relationships in LINQ queries

Listing 5-31: Querying a typed DataSet with LINQ

Listing 5-32: Querying an untyped DataSet with LINQ

Listing 5-33: A handmade Customer entity

Listing 5-34: An ADO.NET Entity Framework auto-generated Customer entity

Listing 5-35: A query to select all the Italian customers

Listing 5-36: A LINQ query over a sequence of Customers entities

Chapter 6: LINQ to XML

Listing 6-1: A sample of XML functional construction

Listing 6-2: A sample of Visual Basic 9.0 XML literals

Listing 6-3: A sample XElement constructed using the LINQ to XML API

Listing 6-4: Definition of an XML element using DOM

Listing 6-5: Definition of an XML element using Visual Basic 9.0 XML literals

Listing 6-6: Sample of explicit type casting using XElement content

Listing 6-7: Sample of explicit escaping of XML text

Listing 6-8: Sample usage of the AddAfterSelf method of XNode

Listing 6-9: A LINQ to XML sentence merged with LINQ queries

Listing 6-10: A LINQ to XML sentence merged with LINQ queries, using Visual Basic 9.0 XML literals

Listing 6-11: XML namespace handling using classic DOM syntax

Listing 6-12: LINQ to XML namespace declaration

Listing 6-13: Visual Basic 9.0 XML literals used to declare XML content with a default XML namespace

Listing 6-14: Multiple XML namespaces within a single XElement declaration

Listing 6-15: LINQ to XML declaration of an XML namespace with a custom prefix

Listing 6-16: Visual Basic 9.0 XML literals used to declare an XML namespace with a custom prefix

Listing 6-17: Visual Basic 9.0 XML literals and global XML namespaces

Listing 6-18: C# 3.0 syntax used to define a default namespace and a custom prefix for one

Listing 6-19: Annotations applied to an XElement instance

Listing 6-20: Example of tag replacement using the XElement ReplaceWith method

Listing 6-21: Example of attribute and child element management using XElement methods

Listing 6-22: A sample LINQ to XML query based on the Element extension method

Listing 6-23: Another sample LINQ to XML query based on the Elements extension method

Listing 6-24: Source XML with a list of customers

Listing 6-25: Destination XML with a list of customers transformed

Listing 6-26: XSLT to transform XML from Listing 6-24 to Listing 6-25

Listing 6-27: A functional construction used to transform XML from Listing 6-24 to Listing 6-25

Listing 6-28: A Visual Basic 9.0 XML literal used to transform XML from Listing 6-24 to Listing 6-25

Listing 6-29: An XML instance to search with LINQ to XML

Listing 6-30: A LINQ to XML query to extract all city nodes from a customers list

Listing 6-31: A LINQ to XML query to extract all city nodes from a customers list after adding some customers

Listing 6-32: Using LINQ to XML and LINQ queries to query XML content

Listing 6-33: A LINQ query that merges LINQ to XML and LINQ to Objects

Listing 6-34: A LINQ query that merges LINQ to XML and LINQ to Objects, simplified by using the let clause

Listing 6-35: A LINQ query over XML, based on an XSD typed approach

Listing 6-36: An XML Schema Definition for our sample list of customers

Listing 6-37: An XML document with the schema of Listing 6-36, built using the LINQ to XML API

Listing 6-38: XML validation using the Validate extension method

Listing 6-39: XSLT transformation using XslCompiledTransform and the CreateNavigator extension method

Listing 6-40: Sample usage of the XPathEvaluate extension method

Listing 6-41: Sample LINQ query over the result of the XPathSelectElements extension method

Appendix A: ADO.NET Entity Framework

Listing A-1: A classic ADO.NET 2.0 query using a SqlDataReader

Listing A-2: A classic ADO.NET 2.0 query using DbProviderFactories

Listing A-3: A sample object-oriented definition of our conceptual entities

Listing A-4: The Customer and Order EntityType definition within Northwind.CSDL

Listing A-5: The physical data layer Customer and Order definition within Northwind.SSDL

Listing A-6: CSDL and SSDL mapping described by Northwind.MSL

Listing A-7: A sample query against a set of entities, using EntityCommand and EntityConnection

Listing A-8: An excerpt of the Customer type auto-generated from the CSDL file

Listing A-9: An excerpt of the NothwindEntities type auto-generated from the CSDL file

Listing A-10: An ADO.NET Entities query to extract all the customers

Listing A-11: An ADO.NET Entities query to extract all the typed customers

Listing A-12: An ADO.NET Entities query to extract all the customers located in Italy

Listing A-13: An ADO.NET Entities query to extract all the customers of a particular country

Listing A-14: An ADO.NET Entities query to extract all the orders of customers of a specific country

Listing A-15: An ADO.NET Entities query to extract all the customers who placed orders in the last two years

Listing A-16: A LINQ to Entities query to extract all the customers who placed orders in the last two years

Listing A-17: Entity modification and data persistence

Listing A-18: Entity status and concurrency

Listing A-19: Entity modification using TransactionScope