Re Descubriendo A Linq

Re-descubriendo LINQ Jose Fco Bonnin Payvision Blog: http://www.josefcobonnin.com

Agenda

Historia

LINQ Basics

LINQ to XML

LINQ to SQL

LINQ Overview C# 3.0 VB 9.0 Otros… LINQ to SQL LINQ to XML LINQ to DataSets .NET Language Integrated Query LINQ to Objects LINQ to Entities LINQ to Whatever Objetos Datos relacionales <book> <title/> <author/> <year/> <price/> </book> XML

Demo

LINQ

Historia

OR/M

Finales 2000 - Cheops

2001 PDC – Presentación ObjectSpaces

Evolución Lenguaje

2001 BillG Thinkweek – XML Types for C#

2002 XML Conference - X#

2002 Microsoft Research – Polyphonic C#

2003 XML Conference - Xen

2004 Microsoft Research – C ω

2005 PDC - Presentación oficial de LINQ

My First Query

int[] numbers = { 5, 10, 8, 3, 6, 12 };

IEnumerable<int> myFirstQuery = Enumerable.Where(numbers, num => num > 6);

myFirstQuery =

Enumerable.OrderBy(myFirstQuery, n => n);

foreach (int i in myFirstQuery)

{

Console.WriteLine(i);

}

Standard Query Operators I Agrupados por tipo de Operación

Sorting

OrderBy

ThenBy

OrderByDescending

…

Aggregation

Aggregate

Average

Count

LongCount

…

Grouping

GroupBy

ToLookUp

Projection

Select

SelectMany

…

Standard Query Operators II Agrupados por tipo de Ejecución

Immediate

Aggregate

Any

Average

First

…

Deferred - Streaming

Cast

Distinct

Select

Where

…

Deferred – Non Streaming

GroupBy

Join

OrderBy

…

Demo

Immediate and Deferred Execution

Query Expressions Syntax I

from-clause:

from [Type] identifier in expression [join clauses]

i.e from num in new int[] {1, 2, 3, 4}

join clause:

join [Type] identifier in expression on expression equals expression

Query Expressions Syntax II

Query Expression

var a = from p in people

where p.Age > 15

orderby p.Name, p.Age descending

select new { p.Name, p.Surname};

Implicitly Typed Variables Extension Methods Lambda Expression Object Initializer Anonymous Type var a = people.Where(p => p.Age > 15) .OrderBy (p => p.Name) .ThenByDescending(p => p.Age) .Select(p => new p.Name, p.Surname);

Demo

Query Expressions

“ PRE” LINQ to XML – W3C DOM XML

XmlDocument xmlDoc = new XmlDocument();

XmlElement freaks = xmlDoc.CreateElement("Freaks");

xmlDoc.AppendChild(freaks);

XmlElement freak = xmlDoc.CreateElement("Freak");

XmlAttribute freakType = xmlDoc.CreateAttribute("Speciality");

freakType.InnerText = “TFS";

freak.Attributes.Append(freakType);

XmlElement name = xmlDoc.CreateElement("Name");

name.InnerText = "Luis";

freak.AppendChild(name);

XmlElement surname = xmlDoc.CreateElement("Surname");

surname.InnerText = "Fraile";

freak.AppendChild(surname);

<Freaks> <Freak Specialty="TFS"> <Name>Luis</Name> <Surname>Fraile</Surname> </Freak> </Freaks>

“ PRE” LINQ to XML – XML “Lite”

string xml =

“ <Freaks>

<Freak Specialty="{0}"><Name>{1}</Name><Surname>{2}</Surname></Freak>

</Freaks>”;

string formattedXml = string.Format(xml, "TFS", "Luis", "Fraile");

LINQ to XML

Demo

LINQ to XML

Expression Trees

Expression<Func<int,int,int>> exp = (a,b) => a + b

ParameterExpression left = Expression.Parameter(typeof(int), "a");

ParameterExpression right= Expression.Parameter(typeof(int), "b");

BinaryExpression body = Expression.Add(left, right);

Expression expression = Expression.Lambda(body, left, right);

Add a b Left Right Body

Demo

LINQ to SQL != Transact/SQL

LINQ to SQL

¿Sólo para RAD?

Service Oriented Architecture, ¿Se puede o no?

LINQ to SQL o Entity Framework

Demo

LINQ to SQL

Fin

this.Dispose();

Referencias

C# 3.o Specification

http://msdn.microsoft.com/en-us/library/ms364047(VS.80).aspx

The LINQ Project:

http://msdn.microsoft.com/en-us/netframework/aa904594.aspx

Standard Query Operators

http://download.microsoft.com/download/5/8/6/5868081c-68aa-40de-9a45-a3803d8134b8/Standard_Query_Operators.doc

101 Linq Samples

http://msdn.microsoft.com/en-us/vcsharp/aa336746.aspx

Jose Blog:

http://www.josefcobonnin.com

Re Descubriendo A Linq

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