Chapter 7 - Beyond LINQ

Bnei Brak 51202 IsraelParallel LINQ Notes... Bnei Brak 51202 IsraelDesigner Support – Can work objects-first or schema-first... Bnei Brak 51202 IsraelUsing LINQ to Entities using SalesEn

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LINQ via C# 3.0

Chapter 7 – Beyond LINQ

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Parallel LINQ Notes

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ADO.NET Entity Framework

– Business entities – Conceptual model – Relational data

– Single class  multiple tables – Many-to-many relationships – Arbitrary queries (Entity-SQL) – Will support providers other than SQL Server®

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Designer Support

– Can work objects-first or schema-first

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[DataContract(IsReference = true), Serializable]

public partial class SaleInfo : EntityObject {

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Using LINQ to Entities

using (SalesEntities context = new

SalesEntities()) {

var everyone =

context.CreateQuery<SalesPerson>(

"SELECT VALUE sp FROM SalesPeople AS sp" );

foreach (var p in everyone)

Amount = g.Sum(s => s.Amount) };

foreach (var info in

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Entity Framework vs LINQ to SQL

– It’s not just a RAD drag-and-drop tool – Moderate learning curve

– Steep learning curve

– Discussion: http://tinyurl.com/5wa5qk,

http://tinyurl.com/573jo8, http://tinyurl.com/6dxeej

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ADO.NET Data Services

ATOM or JSON, REST

– http://example.com/Orders/Order(15) – http://example.com/Orders/BiggestOrders?n=5 – http://example.com/Orders/Order(15)/Products

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Data Services

– T can be LINQ to SQL data context

– T can be Entity Framework model

DataServiceHostFactory

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Out Of The Box

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Out Of The Box

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Out Of The Box

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Service Operations

[WebGet]

public IQueryable<SaleInfo> TopSales(int n) {

return (from sale in

information)

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Service Operations

[WebGet]

public IQueryable<SaleInfo> TopSales(int n) {

return (from sale in

this CurrentDataSource.Sales

orderby sale.Amount descending

select sale).Take(n);

}

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Client Code

System.Data.Services.Client.dll

– And the companion DataSvcUtil.exe tool

– (Works with a conceptual model directly as well!)

– Can work with shared data contracts – Can generate only the contracts we need – WCF SP1 features support for POCO (don’t need

[DataContract] or [DataMember] on anything)

– Can work with DataSvcUtil-generated classes

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Client Code – Manual

class SaleInfo { //POCO

public int Id { get; set; } //Plain Old CLR Object

public int Amount { get; set; }

}

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Client Code – Generated

public partial class SalesEntities :

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Client Code – Generated

SalesEntities context2 = new SalesEntities(

• The query is effectively “serialized”

• A small subset of query operators is supported

• Most work has to be done on the client

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Data Services Over LINQ to SQL

• Any DataContext-assignable class can

• Table<T> does not implement

IUpdatable

– This means that insert, delete and update operations

over the client context will fail

– http://tinyurl.com/5ranan

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Data Services – Quirks with LINQ to SQL

foreign keys) don’t work by default

– A primary key is required

– Resolve with [DataServiceKey(“FK1”, “FK2”)]

on the generated class (partial)

don’t work by default

– The [DataServiceKey] attribute is required

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Custom LINQ Providers

IEnumerable or the query pattern

– Parsing the query expression tree – Translating it to SQL (e.g LINQ to Oracle), web service calls (e.g LINQ to Amazon), other system APIs (e.g LINQ to WMI)

– List of providers: http://tinyurl.com/yt8ala

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Some Custom LINQ Providers

• LINQ to… Your Own!

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Chapter Summary

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Tiêu đề	Beyond linq
Trường học	SELA Software & Education Labs Ltd.
Chuyên ngành	Computer Science
Thể loại	bài viết
Thành phố	Bnei Brak

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