Review Questions Weeks 1-3

Review Questions Weeks 1-3.md

Review Questions Weeks 1-3

MVC & Rails

Diagram and explain the MVC model

• controller: Coordinates the response to an HTTP request and parses user requests, data submissions, cookies, sessions.
• models: Contains all business logic and contains data for the application.
• view: Templates for pages that we will display to our user. data placeholders.
• DMed diagram via slack.

What is the role of the model?

• Interacts with and reflects a table in a database. It also sets validations, methods and other attributes.

When would you want to use a class method rather than an instance method?

• You use class methods when the functionality you are writing does not belong to an instance of that class.
• You use instance methods when manipulate or use a particular instance of the class.

What is the role of a view? What language(s) would you use in a view?

• Template for the http response to render the information for the user ,languages used are html and erb(embedded ruby).

What is the role of the controller?

• Passes data between the model and the view, and sends the output back to the user. What are the 7 RESTful CRUD actions?
• index, edit, update, show, new, create, destroy

Create a chart for Users with columns for path_helpers, HTTP Verb, URI, ActiveRecord, Redirect/Render, View.

path_helpers          | HTTP | Verb    | URI             | ActiveRecord                  | Redirect/Render | View
users_path            |      | get     |/users           |users = User.all               | render          |index
user_path(user)       |      | get     |/users/:id       |user = User.find(user_params)  | render          |show
new_user_path         |      | get     |/users/new       |user = User.new                | render          |new
edit_user_path(user   |      | get     |/users/:id/edit  |user = User.find(user_params)  | render          |edit
user_path(user)       |      |put/patch|/users/:id/update|user = User.find(user_params)  | redirect        |show
                                                         user.update                                            
users_path            |      | post    |/users           |user = User.create(user_params)| redirect        |show/index
                                                         |user.save                                               
user_path(user)       |      | delete  |/users/:id       |user = User.find(user_params)  | redirect        |index
                                                         |user.delete                                             

HTTP

What are the 5 HTTP Verbs?

• get, post, put, patch, delete.

Diagram and explain the HTTP request/response cycle.

• DMed diagram via slack.

HTML/CSS

What HTML tags would you use for the following? section header:

...

• general content: <p>..</p>
• bullet points: <ul>..</ul>
• numbered list: <li>..</li>
• image: <img>..</img>
• link: <a href..</a>

form & its pieces How do you target the following in CSS? a class: .class an id: #id an element: *

Testing

How would you set up a test to check that a User has an email address and that only one user can have that email address? in the model I validate that the email is unique.

  class Fu < ActiveRecord::Base
   validates_uniqueness_of :email
  end

# spec
  describe Fu do
    it "should have a unique email" do
      Fu.create!(:email=>"Fu@bar.com")
      fu = Fu.new(:email=>"Fu@bar.com")
      fu.should_not be_valid
      fu.errors[:email].should include("has already been taken")
    end
  end

How would you set up a test to check that a specific User is listed on a page?

• expect(page).to have_content("#{user.name}")

Databases

What is the SQL to pull the record for every User?

• SELECT * FROM users;

What is the SQL to pull the record for how many Users are in the database?

• SELECT COUNT(id) FROM users;

Diagram the tables of a database where a User has_many Assignments, an Assignment belongs_to a User, a Course has_many Assignments, and an Assignment belongs_to a Course.

• DMed diagram via slack.

ActiveRecord

When would I use a find, vs a find_by, vs a where?

• find only finds by the id and find_by finds the first object by any column/att. where finds all records that match the specified attribute.

What ActiveRecord methods would I use in each of the 7 CRUD actions?

• index: all
• new: new
• create: new, save or create
• edit: find
• update: find, update
• destroy: find, delete
• show: find

How do I make it so I can call user.assignments? What about assignment.users?

• in the user model has_many :assignments and in the assignments model has_many :users.