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Principles of MVC For rails Developers
View Ruby On Rails Course at: www.edureka.co/ruby-on-rails
For more details please ...
Slide 2 www.edureka.co/ruby-on-rails
Objectives
At the end of this module, you will be able to understand:
 Challenges Fa...
Slide 3 www.edureka.co/ruby-on-rails
Challenges Faced when Designing an Application without a Framework
 Complexity in di...
Slide 4 www.edureka.co/ruby-on-rails
 Leads to disorganization  Change one thing, break another
Challenges Faced when De...
Slide 5 www.edureka.co/ruby-on-rails
The Solution is to use Design Patterns
Design Patterns is the way to organize a progr...
Slide 6 www.edureka.co/ruby-on-rails
Introduction – What is MVC
MVC Introduction
MVC is acronym for Model-View-Controller
...
Slide 7 www.edureka.co/ruby-on-rails
 Originally described in terms of a design pattern for use with Smalltalk by Trygve ...
Slide 8 www.edureka.co/ruby-on-rails
MVC - Illustration
Web
Browser/Client
HTTP Request
HTTP Response
CONTROLLER MODEL
VIE...
Slide 9 www.edureka.co/ruby-on-rails
Model
Data access routines and some business logic can be defined in the model.
Model...
Slide 10 www.edureka.co/ruby-on-rails
View
Views define exactly what is presented to the user.
It collects data from the u...
Slide 11 www.edureka.co/ruby-on-rails
Controller
Controllers bind the whole pattern together.
Controller is intermediary b...
Slide 12 www.edureka.co/ruby-on-rails
DRY
 DRY just means "Don't Repeat Yourself". Make sure that when you write code, yo...
Slide 13 www.edureka.co/ruby-on-rails
Convention Over Configuration
 Convention over configuration (also known as coding ...
Slide 14 www.edureka.co/ruby-on-rails
MVC Benefits
Slide 15 www.edureka.co/ruby-on-rails
 Rails application can be created using the following command
>rails new app_name
...
Slide 16 www.edureka.co/ruby-on-rails
Directory Layout
File /Folder Purpose
app/
Contains the controllers, models, views, ...
Slide 17 www.edureka.co/ruby-on-rails
Directory Layout (Contd.)
File /Folder Purpose
public/ The only folder seen by the w...
Slide 18 www.edureka.co/ruby-on-rails
 Rails application can be booted using the
following command
>rails server
 This c...
Slide 19 www.edureka.co/ruby-on-rails
To see your application in action, open a browser window and navigate to http://loca...
Slide 20 www.edureka.co/ruby-on-rails
Demo on
MVC in Rails
Questions
Slide 21 www.edureka.co/ruby-on-railsTwitter @edurekaIN, Facebook /edurekaIN, use #AskEdureka for Questions
Principles of MVC for Rails Developers
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Principles of MVC for Rails Developers

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Ruby on Rails training certifies you with in demand Web Application Technologies to help you grab the top paying IT job title with Web Application skills and expertise in Full Stack. Rails is written in Ruby, which is a language explicitly designed with the goal of increasing programmer happiness. This unbiased and universal view makes Ruby on Rails unique in today's Job market as a leader in the Web Application platform.

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Principles of MVC for Rails Developers

  1. 1. Principles of MVC For rails Developers View Ruby On Rails Course at: www.edureka.co/ruby-on-rails For more details please contact us: US : 1800 275 9730 (toll free) INDIA : +91 88808 62004 Email Us : webinars@edureka.co For Queries: Post on Twitter @edurekaIN: #askEdureka Post on Facebook /edurekaIN
  2. 2. Slide 2 www.edureka.co/ruby-on-rails Objectives At the end of this module, you will be able to understand:  Challenges Faced when Designing an Application Without Framework  MCV Design Patterns  Logic Behind MVC  DRY and Convention Over Configuration  MVC Benefits  Demo on MVC in RAILS
  3. 3. Slide 3 www.edureka.co/ruby-on-rails Challenges Faced when Designing an Application without a Framework  Complexity in direct coding  Everything must be tested, which is difficult  Difficult to re-use code  Hard code everything from scratch  Teamwork challenges - parallel programming cannot be done efficiently
  4. 4. Slide 4 www.edureka.co/ruby-on-rails  Leads to disorganization  Change one thing, break another Challenges Faced when Designing an Application without a Framework
  5. 5. Slide 5 www.edureka.co/ruby-on-rails The Solution is to use Design Patterns Design Patterns is the way to organize a program in a proper manner One such design pattern is MVC
  6. 6. Slide 6 www.edureka.co/ruby-on-rails Introduction – What is MVC MVC Introduction MVC is acronym for Model-View-Controller A software design pattern for developing web and desktop applications In simple words, a better way of separating the logic of your application from the display.
  7. 7. Slide 7 www.edureka.co/ruby-on-rails  Originally described in terms of a design pattern for use with Smalltalk by Trygve Reenskaug in 1979.  His paper was published under the title "Applications Programming in Smalltalk-80: How to use Model-View- Controller", and paved the groundwork for most future MVC implementations.  MVC design pattern is used to separate an application’s data, business logic, and presentation; doing so facilitates the creation of more maintainable, reusable, and testable code. • Model - Data Layer • View - User Interface Layer • Controller - Interacts with the Model MVC Introduction
  8. 8. Slide 8 www.edureka.co/ruby-on-rails MVC - Illustration Web Browser/Client HTTP Request HTTP Response CONTROLLER MODEL VIEW Data object Request Data Objects Response Render dataEvents (GET/POST) Handled by Framework (Hidden from user) Database Database Request Raw Data Response MVC Container Website User http://www.mywebsite.com
  9. 9. Slide 9 www.edureka.co/ruby-on-rails Model Data access routines and some business logic can be defined in the model. Model is responsible for providing the data from the database and saving the data into the data store. Models are active representations of database tables: they can connect to your database, query it (if instructed to do so by a controller) and save data to the database. No interaction between models and views: all the logic is handled by controllers. MVC - Data Layer
  10. 10. Slide 10 www.edureka.co/ruby-on-rails View Views define exactly what is presented to the user. It collects data from the user and gives it to controller and controller invokes the required model. Controllers pass data to each view to render in some format. Views can be described as template files that present their content to the user: variables, arrays and objects that are used in views are registered through a controller. Views should not contain complex business logic; only the elementary control structures necessary to perform particular operations, such as the iteration of collected data through a foreach construct, should be contained within a view. MVC - User Interface Layer
  11. 11. Slide 11 www.edureka.co/ruby-on-rails Controller Controllers bind the whole pattern together. Controller is intermediary between View and Model. Controllers contain the logic of your application. Each controller can offer different functionality; controllers retrieve and modify data by accessing database tables through models; and they register variables and objects, which can be used in views. Once request is received from client it executes the appropriate business logic from the model, decide which view to display based on the user's request and other factors, pass along the data that each view will need, or hand off control to another controller entirely. MVC - Interacting With Model
  12. 12. Slide 12 www.edureka.co/ruby-on-rails DRY  DRY just means "Don't Repeat Yourself". Make sure that when you write code, you only write it one time.  The DRY principle is stated as "Every piece of knowledge must have a single, unambiguous, authoritative representation within a system." Reference: https://maurits.wordpress.com
  13. 13. Slide 13 www.edureka.co/ruby-on-rails Convention Over Configuration  Convention over configuration (also known as coding by convention) is a software design paradigm which seeks to :  For example, if there is a class Sale in the model, the corresponding table in the database is called "sales" by default. It is only if one deviates from this convention, such as calling the table "product sales", that one needs to write code regarding these names. Not losing flexibility Decrease number of decisions on developers Gain Simplicity
  14. 14. Slide 14 www.edureka.co/ruby-on-rails MVC Benefits
  15. 15. Slide 15 www.edureka.co/ruby-on-rails  Rails application can be created using the following command >rails new app_name  When you create an application using the rails helper script, you can see that a new directly structure is created for your application. The directory structure will have to following directories that will be explained in the next slide. Creating a Rails Application
  16. 16. Slide 16 www.edureka.co/ruby-on-rails Directory Layout File /Folder Purpose app/ Contains the controllers, models, views, helpers, mailers and assets for your application. bin/ Contains the rails script that starts your app and can contain other scripts you use to deploy or run your application. config/ Configure your application's routes, database, and more condig.ru Rack configuration for Rack based servers used to start the application. db/ Contains your current database schema, as well as the database migrations Gemfile Gemfile.lock These files allow you to specify what gem dependencies are needed for your Rails application. These files are used by the Bundler gem. Lib/ Extended modules for you application Log/ Application log files
  17. 17. Slide 17 www.edureka.co/ruby-on-rails Directory Layout (Contd.) File /Folder Purpose public/ The only folder seen by the world as-is. Contains static files and compiled assets. Rakefile This file locates and loads tasks that can be run from the command line. Rather than changing Rakefile, you should add your own tasks by adding files to the lib/tasks directory of your application README.rdoc This is a brief instruction manual for your application. You should edit this file to tell others what your application does, how to set it up, and so on. test/ Unit tests, fixtures, and other test apparatus. tmp/ Temporary files (like cache, pid, and session files). Vendor/ A place for all third-party code. In a typical Rails application this includes vendor’s gems.
  18. 18. Slide 18 www.edureka.co/ruby-on-rails  Rails application can be booted using the following command >rails server  This command will fire up WEBrick, a web server distributed with Ruby. » Default environment is development » Default port is 3000 » http://127.0.0.1:3000 Running Rails Application
  19. 19. Slide 19 www.edureka.co/ruby-on-rails To see your application in action, open a browser window and navigate to http://localhost:3000 Running Rails Application (Contd.)
  20. 20. Slide 20 www.edureka.co/ruby-on-rails Demo on MVC in Rails
  21. 21. Questions Slide 21 www.edureka.co/ruby-on-railsTwitter @edurekaIN, Facebook /edurekaIN, use #AskEdureka for Questions

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