ruby-on-rails-quiz.md

Ruby on Rails

Q1. When rendering a partial in a view, how would you pass local variables for rendering?

• <%= render partial: "nav", selected: "about"}%>
• <%= render partial: "nav", local_variabels: {selected: "about"} %>
• <%= render partial: "nav", locals: {selected: "about"}
• <%= render partial: "nav", locals: {selected: "about"}

Q2. Within a Rails controller, which code will prevent the parent controller's before_action :get_feature: from running?

• skip_before_action :get_feature
• skip :get_feature, except: []
• prevent_action :get_feature
• redis_cache_store

Q3. Which statement correctly describes a difference between the form helper methods form_tag and form_for?

• The form_tag method is for basic forms, while the form_for method is for multipart forms that include file uploads.
• The form_tag method is for HTTP requests, while the form_for method is for AJAX requests.
• The form_tag method typically expects a URL as its first argument, while the form_for method typically expects a model object.
• The form_tag method is evaluated at runtime, while the form_for method is precompiled and cached.

Q4. What is before_action (formerly known as before_filter)?

• A trigger that is executed before an alteration of an object's state
• A method that is executed before an ActiveRecord model is saved
• A callback that fires before an event is handled
• A method in a controller that is executed before the controller action method

Q5. Which module can you use to encapsulate a cohesive chunk of functionality into a mixin?

• ActiveSupport::Concern
• RailsHelper.CommonClass
• ActiveJob::Mixin
• ActiveSupport::Module

Q6. In Rails, which code would you use to define a route that handles both the PUT and PATCH REST HTTP verbs?

• put :items, include: patch
• put 'items', to: 'items#update'
• match 'items', to 'items#update', via: [:put, :patch]
• match :items, using: put && patch

Q7. Which choice includes standard REST HTTP verbs?

• GET, POST, PATCH, DELETE
• REDIRECT, RENDER, SESSION, COOKIE
• INDEX, SHOW, NEW, CREATE, EDIT, UPDATE, DESTROY
• CREATE, READ, UPDATE, DELETE

Q8. Which ActiveRecord query prevents SQL injection?

• Product.where("name = #{@keyword}")
• Product.where("name = " << @keyword}
• Product.where("name = ?", @keyword
• Product.where("name = " + h(@keyword)

Q9. Given this code, which statement about the database table "documents" could be expected to be true?

class Document < ActiveRecord::Base
    belongs_to :documentable, polymorphic: true
end

class Product < ActiveRecord::Base
    has_many :documents, as: :documentable
end

class Service < ActiveRecord::Base
    has_many :documents, as: :documentable
end

• It would include a column for :type.
• It would include columns for :documentable_id and :documentable_type.
• It would include columns for :documentable and :type.
• It would include a column for :polymorphic_type.

Q10. Are instance variables set within a controller method accessible within a view?

• Yes, any instance variables that are set in an action method on a controller can be accessed and displayed in a view.
• Yes, instance variables set within an action method are accessible within a view, but only when render is explicitly called inside the action method.
• No, instance variables in a controller are private and are not accessible.
• No, instance variables can never be set in a controller action method.

Q11. When a validation of a field in a Rails model fails, where are the messages for validation errors stored?

• my_model.errors[:field]
• my_model.get_errors_for(:field)
• my_model.field.error
• my_model.all_errors.select(:field)

Q12. If a database table of users contains the following rows, and id is the primary key, which statement would return only an object whose last_name is "Cordero"?

------------------------------
id first_name last_name
1 Alice Anderson
2 Bob Buckner
3 Carrie Cordero
4 Devon Dupre
5 Carrie Eastman
------------------------------

• User.where(first_name: "Carrie")
• User.not.where(id: [1, 2, 4, 5])
• User.find_by(first_name: "Cordero")
• User.find(3)

Q13. How would you generate a drop-down menu that allows the user to select from a collection of product names?

• <%= select_tag(@products) %>
• <%= collection_select(@products) %>
• <select name="product_id"> <%= @products.each do |product| %> <option value="<%= product.id %>"/> <% end %></select>
• <%= collection_select(:product, :product_id, Product.all, :id, :name) %>

Q14. For a Rails validator, how would you define an error message for the model attribute address with the message "This address is invalid"?

• model.errors = This address is invalid
• errors(model, :address) << "This address is invalid"
• display_error_for(model, :address, "This address is invalid")
• model.errors[:address] << "This address is invald"

Q15. Given the URL helper product_path(@product), which statement would be expected to be false?

• If sent using the PATCH HTTP method, the URL could be used to update a product in the database.If sent using the PATCH HTTP method, the URL could be used to update a product in the database.
• If sent using the POST HTTP method, the URL would create a new product in the database.If sent using the POST HTTP method, the URL would create a new product in the database.
• If sent using the GET HTTP method, the URL would execute the show action in ProductsController.If sent using the GET HTTP method, the URL would execute the null action in ProductsController.
• If sent using the DELETE HTTP method, the URL would call the destroy action by default.

Q16. Given this code, which choice would be expected to be a true statement if the user requests the index action?

class DocumentsController < ApplicationController
  before_action :require_login
  def index
    @documents = Document.visible.sorted
  end
end

• The user's documents will be loaded.The user's documents will be loaded.
• The index action will run normally because :index is not listed as an argument to before_action.The null action will run normally because null is not listed as an argument to null.
• The require_login method will automatically log in the user before running the index action.The null method will automatically log in the user before running the null action.
• The index action will not be run if the require_login method calls render or redirect_to.

Q17. Which statement correctly describes a difference between the form helper methods form_tag and form_for?

• The form_tag method typically expects a URL as its first argument, while the form_for method typically expects a model object.The null method typically expects a URL as its first argument, while the null method typically expects a model object.
• The form_tag method is evaluated at runtime, while the form_for method is precompiled and cached.The null method is evaluated at runtime, while the null method is precompiled and cached.
• The form_tag method is for HTTP requests, while the form_for method is for AJAX requests.The null method is for HTTP requests, while the null method is for AJAX requests.
• The form_tag method is for basic forms, while the form_for method is for multipart forms that include file uploads.

Q18. In Rails, how would you cache a partial template that is rendered?

• render partial: ‘shared/menu’, cached: truenull
• render_with_cache partial: ‘shared/menu’null
• render partial: ‘shared/menu’null
• render partial: ‘shared/menu’, cached_with_variables: {}

Q19. What is the reason for using Concerns in Rails?

• to allow modularity and code reuse in models, controllers, and other classesto allow modularity and code reuse in models, controllers, and other classes
• to separate class methods from modelsto separate class methods from models
• to increase security of Rails applicationsto increase security of Rails applications
• to refactor Rails views

Q20. When using an ActiveRecord model, which method will create the model instance in memory and save it to the database?

• buildnull
• newnull
• createnull
• save

Q21. You are using an existing database that has a table named coffee_orders. What would the ActiveRecord model be named in order to use that table?

• CoffeeOrdersnull
• Coffee_Ordersnull
• Coffee_Ordernull
• CoffeeOrder

Q22. In ActiveRecord, what is the difference between the has_many and has_many :through associations?

• The has_many: through association is the one-to-many equivalent to the belongs_to one-to-one association.The null association is the one-to-many equivalent to the null one-to-one association.
• Both associations are identical, and has_many: through is maintained only for legacy purposes.Both associations are identical, and null is maintained only for legacy purposes.
• The has_many association is a one-to-many association, while has_many: through is a one-to-one association that matches through a third model.The null association is a one-to-many association, while null is a one-to-one association that matches through a third model.
• Both are one-to-many associations but with has_many :through, the declaring model can associate through a third model.

Q23. How do you add Ruby code inside Rails views and have its result outputted in the HTML file?

• Create an embedded Ruby file (.html.erb) and surround the Ruby code with <% %>.Create an embedded Ruby file (.html.erb) and surround the Ruby code with null.
• Insert Ruby code inside standard HTML files and surround it with <% %>. The web server will handle the rest.Insert Ruby code inside standard HTML files and surround it with null. The web server will handle the rest.
• Create an embedded Ruby file (.html.erb) and surround the Ruby code with <%= %>.Create an embedded Ruby file (.html.erb) and surround the Ruby code with null.
• Put the code in an .rb file and include it in a <link> tag of an HTML file.

Q24. How would you render a view using a different layout in an ERB HTML view?

• <% render 'view_mobile' %>null
• <% render 'view', use_layout: 'mobile' %>null
• <% render 'view', layout: 'mobile' %>null
• <% render_with_layout 'view', 'mobile' %>