Ruby on Rails

Question 1

Gem Specification:

gem ‘rails’, ‘4.0.0’

Answer 1

is “absolute”, only version 4.0.0 will be used

Question 2

Gem Specification:

gem ‘rails’, ‘>= 4.0.0’

Answer 2

is “optimistic”, any version newer than 4.0.0 will be used

Question 3

Gem Specification:

gem ‘rails’, ‘~> 4.0.0’

Answer 3

“pessimistic”;

~> 4.0.0 means use
any version greater than 4.0.0 and less than 4.1 (any patch version can be used). ~> 4.0
means use any version greater than 4.0 and less than 5.0 (any minor version can be used).

Question 4

Changes in routes file

Answer 4

When you change the config/routes.rb file, you must restart your application server to see
the new behavior.

Question 5

Can a controller use data from more than one model?

Answer 5

. In Rails, though a controller can use data from more than one model,
there is often a model with the same name as a controller

Question 6

How do you pass variables to the view file from the controller?

Answer 6

Any instance variables (variables named with the @

character) will be available in the corresponding view file.

Question 7

understanding params (add more)

Answer 7

params = {controller: ‘contacts’,
action: ‘process_form’,
contact: {name: ‘Daniel’ , email: ‘daniel@danielkehoe.com@’, content: ‘hi!’}
}

Question 8

skinny controller, fat model

Answer 8

Controllers should
contain only enough code to instantiate a model and handle rendering. If you think about it,
adding a subscriber to the MailChimp database is a data operation, and all data
manipulation should be handled by a model.

Question 9

How do you run bundle without installing production gems?

Answer 9

bundle install –without production

Question 10

Why do you need to precompile assets?

Answer 10

If you don’t precompile assets for production, all web pages will look strange. They won’t
have CSS styling.

Question 11

How do instance variables help performances?

Answer 11

Setting an instance variable (in controller) caches the data so it doesn’t make a new database call each find the instance is searched for.

Question 12

What does t.timestamps create?

Answer 12

It will create two columns inside our table titled created_at and updated_at

Question 13

What are the 7 core actions of rails’ REST implementation?

Answer 13

index
new
create
show
update
edit
destroy

Question 14

What is form_for and how do you use it?

Answer 14

form_for is a Rails helper method which takes one parameter, in this case @article and a block with the form fields. The first line basically says “Create a form for the object named @article, refer to the form by the name f and add the following elements to the form…”

Example:

<li></li>

</ul>

<p>
<br></br>

</p>

<p>
<br></br>

</p>

<p>

</p>

Question 15

How is form data accessible?

Answer 15

The data from the form will be accessible through the params method.

Question 16

Where should flash messages be added?

Answer 16

In the layout for use across the entire application.

Question 17

What is the difference between new and create?

Answer 17

new doesn’t send the data to the database until you call save. With create you build and save to the database all in one step

Question 18

Changing a form label - in this case from Author Name to Your Name

Answer 18

<br></br>

Question 19

Note about join tables

Answer 19

Most of the time a join table isn’t the best solution, so promote the joining feature to its own model

Question 20

Rails offers four standard spots to place initialization code. Where are they?

Answer 20

config/application.rb
Environment-specific configuration files
Initializers
After-initializers

Question 21

What is bundler?

Answer 21

Bundler is a tool that manages gem dependencies for your Ruby application. The first time bundler is used is when the application is created - automatically built in.

Question 22

What gem does the application use if you don’t include a version?

Answer 22

The gem directive takes an optional second argument describing the version of the Rubygem desired. Leaving the version argument off will simply get the latest available stable version, which may not be the latest version available. To include a release candidate or a pre-release gem you’ll need to specify the version explicitly.

Question 23

Rails routing order

Answer 23

Routes are consulted, both for recognition and for generation, in the order they are defined in routes.rb. The search for a match ends when the first match is found, meaning that you have to watch out for false positives.

Question 24

Don’t use numbered IDs in URLs

Answer 24

Why shouldn’t you use numeric IDs in your URLs? First, your competitors can see just how many auctions you create. Numeric consecutive IDs also allow people to write automated spiders to steal your content. It’s a window into your database. And finally, words in URLs just look better.

Question 25

The belongs_to association supports these 9 options:

Answer 25

\:autosave
\:class_name
\:counter_cache
\:dependent
\:foreign_key
\:inverse_of
\:polymorphic
\:touch
\:validate

Question 26

:class_name option

Answer 26

If the name of the other model cannot be derived from the association name, you can use the :class_name option to supply the model name. For example, if an order belongs to a customer, but the actual name of the model containing customers is Patron, you’d set things up this way:

class Order < ActiveRecord::Base
  belongs_to :customer, class_name: "Patron"
end

Question 27

:foreign_key option for associations

Answer 27

By convention, Rails assumes that the column used to hold the foreign key on this model is the name of the association with the suffix _id added. The :foreign_key option lets you set the name of the foreign key directly:

class Order < ActiveRecord::Base
  belongs_to :customer, class_name: "Patron",
                        foreign_key: "patron_id"
end

Question 28

Does rails create foreign keys automatically?

Answer 28

In any case, Rails will not create foreign key columns for you. You need to explicitly define them as part of your migrations.