Ruby On Rails Classroom
Neha Jaggi /
Professional /
Web Technology
- Foreword to the First Edition
- Acknowledgments
- About the Author
- From Zero to Deploy
- Development Environments
- Ruby RubyGems Rails and Git
- The First Application
- rails server
- Model-view-controller MVC
- Version Control with Git
- What Good Does Git Do You
- GitHub
- Branch Edit Commit Merge
- Deploying
- Heroku Setup
- Conclusion
- A Demo App
- Planning the Application
- Modeling Demo Users
- Modeling Demo Microposts
- The Users Resource
- A User Tour
- MVC in Action
- Weaknesses of this Users Resource
- The Microposts Resource
- A Micropost Microtour
- Putting the micro in Microposts
- A User has many Microposts
- Inheritance Hierarchies
- Deploying the Demo App
- Conclusion
- Static Page
- Mostly Static Pages
- Truly Static Pages
- Static Pages with Rails
- Our First Tests
- Test-driven Development
- Adding a Page
- Testing a Title Change
- Passing Title Tests
- Embedded Ruby
- Eliminating Duplication with Layouts
- Conclusion
- Advanced Setup
- Eliminating bundle exec
- Automated Tests with Guard
- Speeding up Tests with Spork
- Tests inside Sublime Text
- Rails-Flavored Ruby
- Strings and Methods
- Objects and Message Passing
- Method Definitions
- Other Data Structures
- Blocks
- Hashes and Symbols
- CSS revisited
- Ruby Classes-Constructors
- Class Inheritance
- Modifying Built-in Classes -A Controller Class
- A User Class
- Conclusion-Exercises
- Adding Some Structure
- Site Navigation
- Bootstrap and Custom CSS
- Partials
- Sass and the Asset Pipeline
- Syntactically Awesome Stylesheets
- Layout Links
- Route Tests
- Rails Routes
- Named Routes
- Pretty RSpec
- User Signup A First Step
- Signup URI
- Conclusion-Exercises
- Modeling Users
- User Model
- Database Migrations
- The Model File
- Creating User Objects
- Finding User Objects
- Updating User Objects
- User Validations
- Validating Presence
- Length Validation-Format Validation
- Uniqueness Validation
- Adding a Secure Password
- An Encrypted Password
- Password and Confirmation
- User Authentication
- User Has Secure Password
- Creating a User
- Conclusion-Exercises
- Showing Users
- Debug and Rails Environments
- A Users Resource
- Testing the User Show Page with Factories
- A Gravatar Image and a Sidebar
- Signup Form
- Tests for User Signup
- Using form for
- The Form HTML
- Signup Failure
- Signup Error Messages
- The Finished Signup Form
- The Flash
- Deploying to Production with SSL
- Conclusion-Exercises
- Sessions and Signin Failure
- Sessions Controller
- Signin Tests
- Signin Form
- Reviewing Form Submission
- Rendering with a Flash Message
- Signin Success
- Remember Me
- A Working sign in Method
- Current User
- Changing the Layout Links
- Signin upon Signup
- Signing Out
- Introduction to Cucumber Optional
- Installation and Setup
- Features and Steps
- Counterpoint RSpec Custom Matchers
- Conclusion-Exercises
- Updating Users
- Edit Form
- Unsuccessful Edits
- Successful Edits
- Authorization
- Requiring Signed-in Users
- Requiring the Right User
- Friendly Forwarding
- Showing All Users
- User Index
- Sample Users
- Pagination
- Partial Refactoring
- Deleting Users-Administrative Users
- The destroy Action
- Conclusion-Exercises
- A Micropost Model
- The Basic Model
- Accessible Attributes and the First Validation
- User Micropost Associations
- Micropost Refinements
- Content Validations
- Showing Microposts
- Augmenting the User Show Page
- Sample Microposts
- Manipulating Microposts
- Access Control
- Creating Microposts
- A Proto-feed
- Destroying Microposts
- Conclusion-Exercises
- Following Users
- The Relationship Model
- A Problem with the Data Model and a Solution
- User Relationship Associations
- Validations
- Followed users
- Followers
- Sample Following Data
- Stats and a Follow Form
- Following and Followers Pages
- A Working Follow Button the Standard Way
- A Working Follow Button with Ajax
- Making the output of find readable in shell
- CRUD Operation-Create
- The Status Feed
- Motivation and Strategy
- A First Feed Implementation
- Subselects
- The New Status Feed
- Conclusion
- Exercises
Ruby On Rails Lesson
Of course, user_with_same_email.valid? is true, because the uniqueness vali- dation is currently case-sensitive, but we want it to be false. Fortunately, :uniqueness accepts an option, :case_sensitive, for just this purpose (Listing 6.21).
Note that we have simply replaced true with case_sensitive: false; Rails infers in this case that :uniqueness should be true. At this point, our application—with an important caveat—enforces email uniqueness, and our test suite should pass.
The Uniqueness Caveat
There’s just one small problem, the caveat alluded to above:
Using validates :uniqueness does not guarantee uniqueness.
D’oh! But what can go wrong? Here’s what:
1. Alice signs up for the sample app, with address alice@wonderland.com.
2. Alice accidentally clicks on ‘‘Submit’’ twice, sending two requests in quick succession.
3 . The following sequence occurs: request 1 creates a user in memory that passes validation, request 2 does the same, request 1’s user gets saved, request 2’s user gets saved.
4. Result: two user records with the exact same email address, despite the uniqueness validation.
If the above sequence seems implausible, believe me, it isn’t: It can happen on any Rails website with significant traffic. Luckily, the solution is straightforward to implement; we just need to enforce uniqueness at the database level as well. Our method is to create a database index on the email column, and then require that the index be unique.
The email index represents an update to our data modeling requirements, which (as discussed in Section 6.1.1) is handled in Rails using migrations. Wesaw in Section 6.1.1 that generating the User model automatically created a new migration (Listing 6.2); in the present case, we are adding structure to an existing model, so we need to create a migration directly using the migration generator:
Unlike the migration for users, the email uniqueness migration is not pre-defined, so we need to fill in its contents with Listing 6.22.14
This uses a Rails method called add_index to add an index on the email column of the users table. The index by itself doesn’t enforce uniqueness, but the option unique: true does.
The final step is to migrate the database:
(If this fails, try exiting any running sandbox console sessions, which can lock the database and prevent migrations.) If you’re interested in seeing the practical effect
Neha Jaggi
Skills Ruby On Rails
Qualifications :- High School - , College/University - Graphic Era Hill University, Dehradun, College/University - ,Location :-Dehradun,Dehradun,UTTARAKHAND,India
Description:-
Experienced Software Developer with a demonstrated history of working in the Information Technology and services industry. Skilled in Web Technologies (Ruby on Rails, PostgreSQL, php, Laravel and AJAX).
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