AgendaSOLID Principles

Dependency Inversion, IoC, Dependency InjectionPros and cons of Dependency InjectionApply DI frameworks into MVC project

AutoMapper – What, Why and How

SOLID Principles• Single Responsibility• Open/Closed• Liskov Substitution• Interface Segregation• Dependency Inversion

Database

Data Access LayerWhich Depends On

Business Logic Layer

Which Depends On

User InterfaceDepends on

DependenciesLower application layers

External servicesOther components

Example Code

Dependencies Inversion (Principle)

Inversion of Control (Pattern)

Service Locator Event Delegate Dependency

Injection

Example Code

Why Dependency Injection

• Loose coupling code• Testability• Clear dependency• Separate of concern• Easy to change

Why NOT Dependency Injection

• Hard to learn• Hard to debug• Object created before needed• More layer => More complexity

Simple DI Container

IoC in ActionUnity

NinjectStructure Map

WhatAn “object to object”

mapper

WhyRemove the boring

mapping code

WhenEntity to DTO

Entity to Data ContactEntity to View Model

Before and after

Mapper in Action