Agenda

• C# 3.0 New Features– Local Variable Type Inference– Object / Collection Initializers– Anonymous Types– Extension Methods– Lambda Expressions– Query Expressions

• LINQ– LINQ to SQL– LINQ to XML– LINQ to Entities– LINQ to DataSet

C# 3.0Part 1

Enums

Expression Trees

Type Safety

GenericsGenerics

IteratorsIterators

Nullable Types

Nullable Types

Anonymous Methods

Anonymous Methods

Managed

Object Oriented

Accessors

Reflection

delegatesObject Initializers

Anonymous Classes

Lambda Expressions

Extension Methods

Local Var’s Type

InferenceLINQ

Partial ClassesPartial

Classes

C# 1.0 , 2.0, 3.0

Why C# 3.0Why C# 3.0

New Features

• Local Variable Type Inference

• Object / Collection Initializers

• Anonymous Types

• Extension Methods

• Lambda Expressions

• Query Expressions

Local Variable Type Inference

int i = 5;string s = "Hello";double d = 1.0;int[] numbers = new int[] {1, 2, 3};Dictionary<int,Order> orders = new Dictionary<int,Order>();

int i = 5;string s = "Hello";double d = 1.0;int[] numbers = new int[] {1, 2, 3};Dictionary<int,Order> orders = new Dictionary<int,Order>();

var i = 5;var s = "Hello";var d = 1.0;var numbers = new int[] {1, 2, 3};var orders = new Dictionary<int,Order>();

var i = 5;var s = "Hello";var d = 1.0;var numbers = new int[] {1, 2, 3};var orders = new Dictionary<int,Order>();

“var” means same type as initializer“var” means same type as initializer

Object / Collection Initializers

public class Point{ public int x, y;}

public class Point{ public int x, y;}

Point a = new Point { x = 0, y = 1};Point a = new Point { x = 0, y = 1};

Point a = new Point();a.x = 0;a.y = 1;

Point a = new Point();a.x = 0;a.y = 1;

Field or property assignments

Object / Collection initializers

List<int> powers = new List<int> { 1, 10, 100, 1000, 10000 };List<int> powers = new List<int> { 1, 10, 100, 1000, 10000 };

Must implement ICollection<T>Must implement ICollection<T>

List<int> powers = new List<int>();powers.Add(1);powers.Add(10);powers.Add(100);powers.Add(1000);powers.Add(10000);

List<int> powers = new List<int>();powers.Add(1);powers.Add(10);powers.Add(100);powers.Add(1000);powers.Add(10000);

Anonymous Types

var x = new { a = 3, b = 5, c = “some text” };var x = new { a = 3, b = 5, c = “some text” };

class __Anonymous1{

private int _a = 3;private int _b = 5;private string _c = “some text”;

public int a { get { return v1; } set { _a = value; } }public int b { get { return v2; } set { _b = value; } }public int c { get { return v3; } set { _c = value; } }

}

class __Anonymous1{

private int _a = 3;private int _b = 5;private string _c = “some text”;

public int a { get { return v1; } set { _a = value; } }public int b { get { return v2; } set { _b = value; } }public int c { get { return v3; } set { _c = value; } }

}

Fits with complex temporarily variables

Extension Methods

public static class Extensions{ public static int ToInt32(this string s) { return Int32.Parse(s); }}

public static class Extensions{ public static int ToInt32(this string s) { return Int32.Parse(s); }}

string s="1234";int i = s.ToInt32(); // Same as Extensions.ToInt32(s)string s="1234";int i = s.ToInt32(); // Same as Extensions.ToInt32(s)

• The ability to extend existing types.– Add new functions to existing classes.

– No need for editing the existing codes.

• Simpler than inheritance.– Inheritance will not work with sealed or primitive types.

– Inheritance is limited by class accessibility.

Lamda Expressions

• Old Programming Concept (λ-calculus).

• Exists in most dynamic languages .– Python, Lisp, Ruby

• Evolution of anonymous functions.

Func<int, int> increment = i => i+1;Increment(10); // result is 11

<Delegate Type> identifier = (<param list>) => <Expression>

Lamda Expressions

delegate string SomeDelegate(string s);delegate string SomeDelegate(string s);

static string TestMethod1(string s){ return s.ToUpper();}…

SomeDelegate d1 = new SomeDelegate(TestMethod1);string a = d1(“abcde");

static string TestMethod1(string s){ return s.ToUpper();}…

SomeDelegate d1 = new SomeDelegate(TestMethod1);string a = d1(“abcde");

SomeDelegate d2 = delegate(string s){

return s.ToUpper();};string a = d2("abcde");

SomeDelegate d2 = delegate(string s){

return s.ToUpper();};string a = d2("abcde");

SomeDelegate d3 = s => s.ToUpper();string a = d3("abcde");SomeDelegate d3 = s => s.ToUpper();string a = d3("abcde");

Implicitly typedImplicitly typed

C# 1.0

C# 2.0

C# 3.0

Query Expressions

var contacts = from c in customers where c.City == “London" select new { c.CustomerID, c.City };

var contacts = customers .Where(c => c.City == “London") .Select(c => new { c.CustomerID, c.City });

Extension methodsExtension methods

Lambda expressionsLambda expressions

Query expressionsQuery expressions

Object initializersObject initializers

Anonymous typesAnonymous types

Implicitly typed Local variableImplicitly typed Local variable

Language INtegrated Query(LINQ)Part 2

Problems

OOP, Inheritance, Polymorphism, Loops,

Conditions …etc(Imperative)

OOP, Inheritance, Polymorphism, Loops,

Conditions …etc(Imperative)

Projection, Join, Grouping, Queries

(Declarative)

Projection, Join, Grouping, Queries

(Declarative)

LINQ Project Goals

• Unified programming model for any data type– Database Relational Data

– XML Files

– Collections & Arrays

• Introduce more declarative syntax– Helps the system find the best execution strategy

• Parallel LINQ (PLINQ)

The LINQ Project

C# 3.0 VB 9.0 Others

.NET Language Integrated Query

LINQ to

DataSets

LINQ to

DataSets

LINQ to

Entities

LINQ to

Entities

LINQ to

Objects

LINQ to

Objects

Objects

LINQ to

XML

LINQ to

XML

<book> <title/> <author/> <year/> <price/></book>

XML

Relational

LINQ to

SQL

LINQ to

SQL

LINQ to SQL

SqlConnection c = new SqlConnection(…);c.Open();SqlCommand cmd = new SqlCommand( @"SELECT c.Name, c.Phone FROM Customers c WHERE c.City = @p0");cmd.Parameters.AddWithValue("@p0", "London“);DataReader dr = c.Execute(cmd);while (dr.Read()) { string name = dr.GetString(0); string phone = dr.GetString(1); DateTime date = dr.GetDateTime(2);}dr.Close();

SqlConnection c = new SqlConnection(…);c.Open();SqlCommand cmd = new SqlCommand( @"SELECT c.Name, c.Phone FROM Customers c WHERE c.City = @p0");cmd.Parameters.AddWithValue("@p0", "London“);DataReader dr = c.Execute(cmd);while (dr.Read()) { string name = dr.GetString(0); string phone = dr.GetString(1); DateTime date = dr.GetDateTime(2);}dr.Close();

Accessing data todayQueries in quotesQueries in quotes

Loosely bound argumentsLoosely bound arguments

Loosely typed result setsLoosely typed result sets

No compile time checksNo compile time checks

public class Customer { … }

public class Northwind: DataContext{ public Table<Customer> Customers; …}

public class Customer { … }

public class Northwind: DataContext{ public Table<Customer> Customers; …}

Northwind db = new Northwind(…);var contacts = from c in db.Customers where c.City == "London" select new { c.Name, c.Phone };

Northwind db = new Northwind(…);var contacts = from c in db.Customers where c.City == "London" select new { c.Name, c.Phone };

LINQ to SQL

Accessing data with LINQ to SQLClasses describe dataClasses describe data

Strongly typed connectionStrongly typed connection

Integrated query syntaxIntegrated query syntax

Strongly typed resultsStrongly typed results

Tables are like collectionsTables are like collections

LINQ to SQL Architecture

from c in db.Customerswhere c.City == "London"select c.CompanyName

Enumerate

SELECT CompanyNameFROM CustomerWHERE City = 'London'

SQL Queryor SProc

Rows

Objects

db.Customers.Add(c1);c2.City = “Seattle";db.Customers.Remove(c3);

SubmitChanges()

INSERT INTO Customer …UPDATE Customer …DELETE FROM Customer …

DML or SProcs

Standard Query Operators

Restriction Where

Projection Select, SelectMany

Ordering OrderBy, ThenBy

Grouping GroupBy

Quantifiers Any, All

Partitioning Take, Skip, TakeWhile, SkipWhile

Sets Distinct, Union, Intersect, Except

Elements First, FirstOrDefault, ElementAt

Aggregation Count, Sum, Min, Max, Average

Conversion ToArray, ToList, ToDictionary

Casting OfType<T>

LINQ to XML

XmlDocument doc = new XmlDocument();XmlElement contacts = doc.CreateElement("contacts");foreach (Customer c in customers) if (c.Country == "USA") { XmlElement e = doc.CreateElement("contact"); XmlElement name = doc.CreateElement("name"); name.InnerText = c.CompanyName; e.AppendChild(name); XmlElement phone = doc.CreateElement("phone"); phone.InnerText = c.Phone; e.AppendChild(phone); contacts.AppendChild(e); }doc.AppendChild(contacts);

XmlDocument doc = new XmlDocument();XmlElement contacts = doc.CreateElement("contacts");foreach (Customer c in customers) if (c.Country == "USA") { XmlElement e = doc.CreateElement("contact"); XmlElement name = doc.CreateElement("name"); name.InnerText = c.CompanyName; e.AppendChild(name); XmlElement phone = doc.CreateElement("phone"); phone.InnerText = c.Phone; e.AppendChild(phone); contacts.AppendChild(e); }doc.AppendChild(contacts);

Programming XML today

<contacts> <contact> <name>Great Lakes Food</name> <phone>(503) 555-7123</phone> </contact> …</contacts>

<contacts> <contact> <name>Great Lakes Food</name> <phone>(503) 555-7123</phone> </contact> …</contacts>

Imperative modelImperative model

Document centricDocument centric

No integrated queriesNo integrated queries

Memory intensiveMemory intensive

LINQ to XML

XElement contacts = new XElement("contacts", from c in customers where c.Country == "USA" select new XElement("contact", new XElement("name", c.CompanyName), new XElement("phone", c.Phone) ));

XElement contacts = new XElement("contacts", from c in customers where c.Country == "USA" select new XElement("contact", new XElement("name", c.CompanyName), new XElement("phone", c.Phone) ));

Programming XML with XLinqDeclarative modelDeclarative model

ElementcentricElementcentric

Integrated queriesIntegrated queries

Smaller and fasterSmaller and faster

Guidance for LINQ to Relational Data

• LINQ to SQL – Strongly Typed Database– Emphasis on rapid application development– Direct mapping to Microsoft SQL Server family of databases– Release in Microsoft Visual Studio 2008 RTM

• LINQ to Entities – Flexible mapping to existing Schema– Focus on enterprise-grade data scenarios– Flexible Mapping to Microsoft SQL Server and third-party databases– Release in Microsoft Visual Studio 2008 update

• CTPs on top of Microsoft Visual Studio 2008 Betas/RTM

• LINQ to DataSet – In-Memory Cache w/Change Tracking– All the scenarios where DataSet is useful today

• Offline, Disconnected, Aggregation• Change Tracking

..Plus support for Query Operations– Strongly typed or Untyped DataSet Support– Release in Microsoft Visual Studio 2008 RTM

LINQ to SQLStrongly typed SQL Database

• Design Points– Rapid Development against SQL Database

• Direct Mapping to SQL Server Schema• Mappings expressed in Attributes or XML file

– "Just Work" for common scenarios• Execute when needed• Naming Conventions

– Business Logic– Custom Insert/Update/Delete operations

– Minimally Intrusive object model– Provide Customization, Optimizations where required

• Targets: Microsoft SQL Server• RTM: Microsoft Visual Studio 2008 RTM

LINQ to SQLDirect Mapping

• Direct Mapping• Each class maps to a single SQL Schema Object

• Table, View

• Stored Procedure, Table Valued Function

• Simple renaming of Tables, Columns

• Foreign Keys can be expressed as Relationships• Properties to navigate in query, results

• Inheritance• Multiple Classes in a Hierarchy can map to a single

Table/View/Stored Proc/TVF with a discriminator column

LINQ to SQLFeatures

• Customization– Business Logic

• Partial classes for generated Objects– Add Methods, non-persistent members, etc.

– Business Logic through Partial methods based on naming conventions

– Update Logic• Implement partial methods in derived Class

– Call Stored Procedures or invoke custom logic

• Optimizations– Loading Options

• ObjectTrackingEnabled

• DeferredLoadingEnabled

– Compiled Query

• Save overhead of SQL generation from Language Expression

LINQ to EntitiesFlexible Mapping to Relational Data

• Design Points• Flexible Mapping to Existing Relational Schema

• Well defined Conceptual model• Share common model across products (Reporting, Analysis, etc…)

• Declarative Mapping between Application and Store• Allows Storage Schema and Application to evolve independently

• Explicit Operations• Server interactions should be explicit

• Build implicit logic on top of explicit operations

• Common Textual "EntitySQL" Language for Ad-Hoc queries

• Targets: Microsoft SQL Server and third-party databases• RTM: Microsoft Visual Studio 2008 Update H1CY08

LINQ to EntitiesFlexible Mapping to Relational Data

• Flexible Mapping• Mapping a single class to multiple tables/views• Mapping to different types of inheritance

• Single Table per Class Hierarchy• Separate Table for each Class in a Hierarchy• Shared Table for Base Class members in a Hierarchy

• Complex (composite) types• i.e., Street, City, Region, and Zip as "Address"

• Directly mapping Many:Many relationships• Mapping to an arbitrary Query

• Store Query• Expose arbitrary store query as a storage Table

• Entity Query• Express mapping as EntitySQL against storage schema

LINQ to EntitiesFeatures

• Customization• Business Logic

• Partial Classes, Events, Partial Methods

• Update Logic• Generated Update Views• Declarative stored procedures

• Optimizations• NoTracking

• Extensibility• Partitioning of Metadata• Flexible Runtime Mapping• Metadata Pluggability

LINQ to DataSetLINQ over Disconnected Cache with Change Tracking

• Disconnected Cache– Offline/Remote

– Data Aggregation

– Application Data

All with Change Tracking

• Queryable– Filter, Projection

– Joins

• Across Tables

• Other in-Memory sources

– Local expressions

All through Common LINQ syntax

• RTM: Microsoft Visual Studio 2008 RTM

LINQ to DataSetTyped and UnTyped

• Untyped DataSet– Call AsEnumerable() on DataTable

– Reference Fields by Name

• Use Field<T>(columnName)– Project out fields for strongly typed result

• Typed DataSet– Use strongly typed accessors

var query = from row in myDataSet.Tables["Customers"].AsEnumerable() where row .Field<string>("City") == "London" select new { row.Field <string> ("CustomerID"),

row.Field <string> ("ContactName") } ;

var query = from customer in northwind.Customers where customer.City == "London" select customer;