NHibernate 4.x Cookbook - Second Edition

NHibernate 4.x Cookbook - Second Edition

By : Gunnar Liljas, Alexander Zaytsev, Jason Dentler

Buy this Book

NHibernate 4.x Cookbook - Second Edition

By: Gunnar Liljas, Alexander Zaytsev, Jason Dentler

Buy this Book

Overview of this book

NHibernate is a mature, flexible, scalable, and feature-complete open source project for data access. Although it sounds like an easy task to build and maintain database applications, it can be challenging to get beyond the basics and develop applications that meet your needs perfectly. NHibernate allows you to use plain SQL and stored procedures less and keep focus on your application logic instead. Learning the best practices for a NHibernate-based application will help you avoid problems and ensure that your project is a success. The book will take you from the absolute basics of NHibernate through to its most advanced features, showing you how to take full advantage of each concept to quickly create amazing database applications. You will learn several techniques for each of the four core NHibernate tasks—configuration, mapping, session and transaction management, and querying—and which techniques fit best with various types of applications. In short, you will be able to build an application using NHibernate by the end of the book. You will also learn how to best implement enterprise application architecture patterns using NHibernate, leading to clean, easy-to-understand code and increased productivity. In addition to new features, you will learn creative ways to extend the NHibernate core, as well as gaining techniques to work with the NHibernate search, shards, spatial, envers, and validation projects.

NHibernate 4.x Cookbook Second Edition

Credits

About the Authors

About the Reviewer

www.PacktPub.com

Customer Feedback

Preface

Free Chapter

The Configuration and Schema

Introduction

Installing NHibernate

Configuring NHibernate with hibernate.cfg.xml

Configuring NHibernate with App.config or Web.config

Configuring NHibernate with code

Configuring NHibernate with Fluent NHibernate

Configuring NHibernate logging

Generating the database

Scripting the database

Updating the database

Using NHibernate schema tool

Models and Mappings

Mapping a class with XML

Creating class hierarchy mappings

Creating class components

Mapping a one-to-many relationship

Mapping a many-to-many relationship

Mapping collections of elements and components

Setting up a base entity class

Handling versioning and concurrency

Mapping by code

Mapping by convention

Creating mappings fluently

Bidirectional one-to-many class relationships

Mapping enumerations

Immutable entities

Mapping relations to non-primary keys

Using lazy properties

Mapping joins

Using calculated properties

Using serializable values

Dynamic components

Mapping <subselect>

Sessions and Transactions

Introduction

Setting up session-per-web request

Setting up session-per-presenter

Creating a session ASP.NET MVC action filter

Creating a transaction ASP.NET MVC action filter

Save entities to the database

Using session.Merge

Using session.Refresh

Handle concurrency using session.Lock

There's more…

Using dictionaries as entities

Using NHibernate with transaction scope

Queries

Introduction

Query entities by ID

Using LINQ to NHibernate

Using CriteriaQueries

Using QueryOver

Using QueryOver projections and aggregates

Using the Hibernate Query Language

Using native SQL

Eager loading with LINQ

Eager loading with Criteria

Eager loading with QueryOver

Eager loading with HQL

Eager loading with SQL

Using named queries

Using detached queries

Using HQL for bulk data changes

Filtering collections

Using result transformers

Extra lazy collections

Improving Performance

Reducing application startup time

Using MultiCriteria

Using MultiQuery

Using Futures

Eager loading child collections

Using stateless sessions

Using read-only entities

Use the second-level cache

Configuring the second-level cache with code

Sharding databases for performance

Testing

Introduction

Using NHibernate Profiler

Profiling NHibernate with Glimpse

Fast testing with the SQLite in-memory database

Preloading data with SQLite

Using Fluent NHibernate persistence testing

Using the Ghostbusters test

Data Access Layer

Introduction

Transaction auto-wrapping for the data access layer

Setting up an NHibernate repository

Using named queries in the data access layer

Using ICriteria in the data access layer

Using paged queries in the data access layer

Using LINQ specifications in the data access layer

Extending NHibernate

Introduction

Creating an encrypted string type

Creating a money type

Using well-known instance types

Using dependency injection with entities

Creating an audit-event listener

Creation and change stamping of entities

Generating trigger-based auditing

Implementing a soft-delete pattern

Setting Microsoft SQL's Context_Info

Using dynamic connection strings

Using custom dialect functions

Using custom functions in LINQ

Extending the LINQ provider

NHibernate Contribution Projects

Introduction

Property validation with attributes

Creating validator classes

Setting up full-text searches

Auditing data with Envers

Using NHibernate Spatial

Index

Customer Reviews

5 star

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2 star

1 star

Filtering collections

In our model with Movies and ActorRoles, we may eventually have movies with hundreds of actors. If we want to display a movie and show all the roles played by Harrison Ford, we certainly can:

 foreach (var actorRole in movie.Actors
                 .Where(x=>x.Actor=="Harrison Ford"))
 {
     Console.WriteLine("Harrison Ford played {0} in {1}", 
         actorRole.Role, 
         movie.Name);
 }

While that would work fine in small data sets, there's a risk that we will load a lot more data than necessary, just to show a couple of roles. What happens is that as soon as we're using the Actors property on each Movie instance, we trigger the lazy loading mechanism and a query will be executed to fetch all ActorRoles of that movie. The Where expression specified doesn't affect this behavior, since it's effectively executed in memory.

For scenarios like this, NHibernate offers a function where an uninitialized (not yet loaded from database) collection can be filtered and...

NHibernate 4.x Cookbook - Second Edition

By : Gunnar Liljas, Alexander Zaytsev, Jason Dentler

NHibernate 4.x Cookbook - Second Edition

By: Gunnar Liljas, Alexander Zaytsev, Jason Dentler

Overview of this book

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NHibernate 4.x Cookbook - Second Edition

Filtering collections