8. Using NHibernate in a Real-world Application | Learning NHibernate 4

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Learning NHibernate 4

By : Suhas H Chatekar

3.6 (9)

Learning NHibernate 4

3.6 (9)

By: Suhas H Chatekar

Overview of this book

This book targets .NET developers who have never used an ORM before, developers who have used an ORM before but are new to NHibernate, or have used NHibernate sparingly and want to learn more about NHibernate.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Introduction to NHibernate

1. Introduction to NHibernate

What is ORM?

What is NHibernate?

What is new in NHibernate 4.0?

NHibernate for users of Entity Framework

Is using ORM a bad idea?

Building blocks of NHibernate

Summary

2. Let's Build a Simple Application

2. Let's Build a Simple Application

Explaining the approach used in learning NHibernate

The problem statement

The development setup

The domain model

Adding some code

Summary

3. Let's Tell NHibernate About Our Database

3. Let's Tell NHibernate About Our Database

Important NHibernate terminology

Mapping the prerequisites

Different mechanisms to write the mappings

XML mappings for the Employee class

Identifier generation

Mapping associations

Mapping inheritance

Mapping components

Mapping by code

Fluent mapping a.k.a. Fluent NHibernate

Choosing the right mapping method

Summary

4. NHibernate Warm-up

4. NHibernate Warm-up

Warming up NHibernate succinctly

The NHibernate session architecture

XML configuration

Programmatic configuration

Loquacious configuration

Fluent configuration

Configuration options

Generating the database scripts from mappings

Summary

5. Let's Store Some Data into the Database

5. Let's Store Some Data into the Database

Entity states

Transactions and unit of work

Saving entities

Transitive persistence using cascade styles

Transitive persistence/cascading in action

Bidirectional associations and ownership

Order of operations

Entity equality

The architecture diagram

Summary

6. Let's Retrieve Some Data from the Database

6. Let's Retrieve Some Data from the Database

Querying the workflow

Different querying methods

Joins

Lazy loading

Eager fetching

Pagination and ordering of results

Retrieving entities by identifiers

Polymorphic queries

Summary

7. Optimizing the Data Access Layer

7. Optimizing the Data Access Layer

Baseline and optimize

Organization of the chapter

Batching

Fetching strategies

Avoiding the select N+1 problem

Avoiding eager fetching

Using extra-lazy for lazy collections

Summary

8. Using NHibernate in a Real-world Application

8. Using NHibernate in a Real-world Application

What kind of application are we building?

Architectural principles we will follow

Feature 1 – onboarding an employee

Unit of work

Feature 2 – updating the details of an employee

Feature 3 – searching employees

Summary

9. Advanced Data Access Patterns

9. Advanced Data Access Patterns

Problems with the repository pattern

Specification pattern

Query object pattern

Summary

10. Working with Legacy Database

10. Working with Legacy Database

Composite IDs

Components

Join-mapping to load data from multiple tables

Working with database views

Using subselect instead of views

Working with stored procedures

Using custom DTOs

Summary

11. A Whirlwind Tour of Other NHibernate Features

11. A Whirlwind Tour of Other NHibernate Features

Concurrency control

Event system

Caching

Stateless sessions

User-defined types

Summary

Index

Index

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Feature 1 – onboarding an employee

In our problem statement, we did not clearly define what happens when a new employee joins. We would detail that out now so that we have something meaningful to work with. Let's say, the following needs to happen when a new employee joins:

Employee is awarded 21 sick leaves and 24 paid leaves
A skill enhancement allowance of £1,000 is allocated
Employee record is saved in database

First two items are clearly a part of business logic. We can say that this logic can live within the Employee class. Third item is not a domain concern but more of an infrastructure concern. So we would want to push it out to one of the outer layers of onion architecture. It is difficult to say which layer this items belongs to exactly. So instead of trying to answer that question now, let's work with what we have got and see where that takes us.

First of all, we would need a controller and an action defined on the controller that accepts a POST request for onboarding a new employee...

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