Simplifying XML Processing using LINQ to XMLBy: Paul D. SheriffPSheriff@pdsa.comwww.pdsa.com or www.PaulSheriffInnerCircle.com

SESSION CODE: DEV320

Paul.AboutPaul D. Sheriff (psheriff@pdsa.com)

President of PDSA, Inc.Custom Software Development, Developer Tools

www.pdsa.comeBooks (www.pdsa.com/eBooks)

Several .NET, SQL Server and SharePoint TopicsDeveloper Tools

.NET Productivity FrameworkPaul Sheriff's Inner Circle

www.PaulSheriffInnerCircle.com

AgendaUsing the System.Xml.Linq NamespaceWhat is LINQLINQ TO XML BasicsLINQ Query SyntaxDemonstrationsA Prototyping System

Goals of this SessionShow you how to use LINQ to XMLUse anonymous typesLoad a class from XMLAdd/Edit/Delete XML files

System.Xml.Linq NamespaceNew classes for dealing with XMLXDocument

Represents a complete, valid XML documentXElement

Represents an XML element or elementsBoth provide XPath query capabilities

XPathSelectElementXPathSelectElements

Build XML in CodeNew syntax=easy creation of XMLImplicit type declarationVB.NETDim menu = _ New XDocument( _ New XDeclaration("1.0", "utf-8", "yes"), _ New XComment("Prototype Menus"), _ New XElement("Menus"))C#var menu = new XDocument( new XDeclaration("1.0", "utf-8", "yes"), new XComment("Prototype Menus"), new XElement("Menus"));

Build XML in Code (2)Create full document

VB.NETDim menu = _ New XDocument( _ New XDeclaration("1.0", "utf-8", "yes"), _ New XComment("Prototype Menus"), _ New XElement("Menus", _ New XElement("Menu", _ New XElement("MenuID", "10"), _ New XElement("DisplayOrder", "10"), _ New XElement("MenuText", "Home") _ )))

VB.NET XML LiteralsOnly available in VB.NETVB.NET Dim menu = _ <Menus> <Menu> <MenuID>10</MenuID> <DisplayOrder>10</DisplayOrder> <MenuText>Home</MenuText> <Action>NextPage.aspx</Action> <ParentMenuID></ParentMenuID> </Menu> </Menus>

Loading a DocumentXDocument.Load("Menus.xml")

Loads a complete valid XML DocumentXElement.Load("Menus.xml")

Loads a set of XML Elements

Build XML / Load Document

DEMO

LINQ to XMLSpecial LINQ syntax for dealing with XMLSimpler than using DOMComparable to using XPath and XQuery

Although syntax is much differentIntelliSense

In VB.NET onlyWhen using XSD

LINQ Query SyntaxStandard “SQL-like” query syntaxVB.NETFrom <element> in <collection> _Where <condition> _Order By <Expression> [Ascending | Descending]Select [<alias> = ] <column>, [<alias> = ] <column>… C#from <element> in <collection> where <condition> orderby <Expression> [ascending | descending]select <column>, <column>…

LINQ Query SyntaxHere is a sample

VB.NETDim menus = From mnu In xElem.<Menu> _ Where mnu.<ParentMenuID>.Value = "" _ Select mnu C#var menus = from mnu in xdoc.Descendants("Menu") where mnu.Element("ParentMenuID").Value == "" select mnu;

Select a Single NodeMethod 1

Load XML using XElement classXElement.Load()

Use the XPathSelectElement methodReturns an XElement object

This is a LINQ Extension methodimport/using System.Xml.XPath namespace

Method 2Use LINQ to XML Syntax

Select Single Node

DEMO

Select Multiple NodesMethod 1

Use the XPathSelectElements methodLINQ Extension method

import/using System.Xml.XPath namespaceCan iterate using For Each / foreach

Method 2Use LINQ Query Syntax

Select Multiple Nodes

DEMO

VB XML ScriptVB Allows you to script in XML LiteralsDim db As New NorthwindDataContext

Dim products = <Products> <%= From prod In db.Products _ Select <Product> <ProductName><%= prod.ProductName%> </ProductName> <UnitPrice><%= prod.UnitPrice %> </UnitPrice> </Product> %> </Products>

VB XML Script

DEMO

Anonymous TypesCreate your own custom typeDefine new field namesCompiler creates new type

Sort of like an on-the-fly classEach field is assigned a data type based on return value

You get IntelliSense on these new names

Anonymous Types

DEMO

Aggregating DataLINQ allows you to aggregate data

Sum, Min, Max, Avg, etc.Instead of you having to loop through all the data, LINQ does it for you

Aggregating Data

DEMO

Adding using LINQMethod 1: VB.NET Only

Use XML LiteralMethod 2

Create XElement object, Populate DataSave XML using XElement.Save method

Method 3Select an XElement using LINQClone ElementSave XML using XElement.Save method

Updating using LINQMethod 1

Select element to updateXPathSelectElement

Update elementSave XML using XElement.Save method

Method 2Select using LINQUpdate elementsSave XML using XElement.Save method

Deleting using LINQMethod 1

Select element to deleteXPathSelectElement

Use the Remove method on the XElementSave XML using XElement.Save method

Method 2Select using LINQRemove the ElementSave XML using XElement.Save method

Add/Edit/Delete using LINQ

DEMO

A Prototype ApplicationProblem:

Want to quickly prototype applicationDon’t want to setup a databaseWould be nice to use XML for menu system

SolutionCreate a standard prototype applicationUse LINQ to XML for all menuing

Can be used on Compact FrameworkLINQ to XML works (LINQ to SQL does not)

A Prototype Application

DEMO

A Wrapper ClassIf you want, you could wrap all these callsCreate class to do all LINQ to XMLJust use the class from the UILater change the class to go to database

A Wrapper Class

DEMO

SummaryLINQ to XML makes processing XML easyFull add/edit/deleteNice Select syntaxShould simplify a lot of XML processing

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Track ResourcesVisual Studio – http://www.microsoft.com/visualstudio/en-us/Soma’s Blog – http://blogs.msdn.com/b/somasegar/ MSDN Data Developer Center – http://msdn.com/data ADO.NET Team Blog – http://blogs.msdn.com/adonet WCF Data Services Team Blog – http://blogs.msdn.com/astoriateam EF Design Blog – http://blogs.msdn.com/efdesign

Resources

www.microsoft.com/techedSessions On-Demand & Community Microsoft Certification & Training Resources

Resources for IT Professionals Resources for Developers

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http://microsoft.com/technet http://microsoft.com/msdn

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JUNE 7-10, 2010 | NEW ORLEANS, LA