Category Archives: Rails

Debugging Rails

Install pry, pry-byebug, and pry-rails gems.
To add a breakpoint, type binding.pry wherever you want your breakpoint to happen.
In console use coninue, step, next, finish commands:

step: Step execution into the next line or method. Takes an optional numeric argument to step multiple times.

next: Step over to the next line within the same frame. Also takes an optional numeric argument to step multiple lines.

finish: Execute until current stack frame returns.

continue: Continue program execution and end the Pry session.

To add shortcuts to ^ commands, add to ~/.pryrc:
Pry.commands.alias_command ‘c’, ‘continue’ rescue nil
Pry.commands.alias_command ‘s’, ‘step’ rescue nil
Pry.commands.alias_command ‘n’, ‘next’ rescue nil
Pry.commands.alias_command ‘f’, ‘finish’ rescue nil

Deploying Rails App to Heroku

My first experience installing a Rails app on Heroku. A pretty easy way to deploy Rails apps.

If you made any changes to your gemfile, make sure to run
bundle install –without production
Even if you already have all of the gems installed. This updates Gemfile.lock, which will be used by Heroku.

If you are on Windows, make sure to remove “.exe” from bundle, rails, and rake inside of your bin folder:
#!/usr/bin/env ruby.exe

Create a free account on Heroku if you don’t have one yet. Download the Heroku Toolbelt.
From the command line:

heroku login
cd path_to_you_app
heroku create

This will create a new Heroku application and set up the remote Git repo. You can optionally specify a name for your app in “heroku create” command, or you can rename it later.

Now, lets push the code to Heroku and run all the DB commands if necessary:

git push heroku master
heroku run rake db:migrate
heroku run rake db:seed
heroku open

To update you app, just push to heroku master.

To get information about your Heroku apps:

heroku apps
heroku ps
heroku logs
heroku run console

The last command will launch a remote Rails console session.

To rename your app:
heroku rename new_name

To destroy your app:
heroku destroy app_name

Starting with RSpec in Rails

Add RSpec related gems to gemfile:

group :development, :test do 
  gem 'rspec-rails'
end

group :test do
  gem "capybara"
end

Capybara is a framework for testing web applications; allows to navigate your app programmatically.

Install your RSpec gems: bundle install

Generate RSpec templates:
generate rspec: rails g rspec:install

To view all available generators: rails g

Since RSpec uses test database, run your migrations for test environment:
rails db:migrate RAILS_ENV=test
If this is the first run, may need to set up the database by running RAILS_ENV=test rake db:reset

To run all specs: rspec
To add formatting: rspec -format doc (or use shortcut: rspec -f doc)
To always use the same formatting, add -format doc to .rspec file.

To use helper files for RSpecs
Uncomment this line in rails_helper.rb:
Dir[Rails.root.join(‘spec/support/**/*.rb’)].each { |f| require f }
And place all your helper methods inside of spec/support directory.

Sample RSpec file:

require 'rails_helper'

describe 'Navigating movies' do
  it 'allows navigation from the detail page to the listing page' do
    movie = Movie.create(movie_attributes)

    visit movie_url(movie)

    click_link 'All Movies'

    expect(current_path).to eq(root_path)
  end

Starting with Rails

Install Ruby. If you are on Windows, 2.3 seems to have issue as of September 2016, so I would go with 2.2.

Install Rails:
gem install rails –version 5.0.0 –no-ri –no-rdoc

Create a new application:
rails _5.0.0_ new application_name
use –skip-test or -T if you don’t want default test files or want to use a different test framework (Test::Unit is default)

Run the application:
rails s

If you are seeing something like this:

Could not load 'active_record/connection_adapters/sqlite3_adapter'. Make sure that the adapter in config/database.yml is valid. If you use an adapter other than 'mysql2', 'postgresql' or 'sqlite3' add the necessary adapter gem to the Gemfile.

You probably have ruby version above 2.2 and you are on Windows. Downgrade to 2.2 or try a different OS.

Create a route for your first action:

verb "url" => "name_of_controller#name_of_action"
get 'movies' => 'movies#index'

Generate/destroy a controller:

rails g controller name_of_controller
rails destroy controller name_of_controller

If you don’t want to use the default framework, add –no-test-framework when generating a controller.

Update your view with something like this:

<ul>
<% @movies.each do |movie| %>

<li> <strong><%= movie.title %></strong> (<%= movie.rating %>) <%= number_to_currency(movie.total_gross) %></li>
<% end %>
<ul>

Create a model

rails generate model NAME [field[:type][:index] field[:type]
rails g model event name:string location:string price:decimal

To generate the whole resource:

rails g resource Resource_name column_name:column_type --no-test-framework

To destroy the resource:

rails destroy resource Resource_name column_name:column_type --no-test-framework

Use any of these DB column types types for your model:

string
text
integer
decimal
float
boolean
binary
date
time
datetime
primary_key
timestamp

To declare foreign key relationship: belongs_to :parent
To reference children in parent model: has_many :children
To cascade deletes: has_many :reviews, dependent: :destroy

To attach parent to child: child.parent = parent
Or, parent.children.new(…)

Run migration:
rails db:migrate
rauks db:migrate:status

Seeds:
Use seeds.rb to create seed records for development
To run: rails db:seed

To look up commands:
rails -T
rails -T db

To Look up routes:
rails routes
In browser: {your_app_base_address}/rails/info/routes

for path/url use route_name_path/route_name_url
In rails command line (rails c):
app.route_name_url
app.route_name_path
app.route_name_path(model)
<%= link_to("Whatever text", route_name_path) %>
Shortcut: <%= link_to("Whatever text", model) %>
Use _path in view templates and _url in controllers as redirects.

Routes with parameters
get ‘route/:id’ => ‘controller#show’, as: ‘some_route_name’
<%= link_to "Whatever text", route_name_path(model) %>
Shortcut: <%= link_to "Whatever text", model %>

Root route
root ‘controller#action’

Submitting Forms
Sample form:

<%= form_for(@movie, @review) do |f| %>
  <p>
    <%= f.label :title %>
    <%= f.text_field :title %>
  </p>
  <% Review::STARS.each do |star| %>
    <%= f.radio_button :stars, star %> <%= star %>
  <% end %>
  <p>
    <%= f.submit %>
  </p>
<% end %>

Updating a model

def update
  @movie = Movie.find(params[:id])
  @movie.update(params[:movie])
end

To allow specific model fields to be updated
params[:movie].permit(:title, :description)

Or (will fail if movie is not submitted)
params.require(:movie).permit(:title)

To allow all fields to be updated:
params.require(:movie).permit!

Working with Active Record
Ordering:
Movie.order(‘released_on’)
Movie.order(‘released_on asc’)
Movie.order(released_on: :asc)

Searching:
Movie.find(2)
Movie.find_by(title: “Iron Man”)
Movie.where(rating: “PG-13”)
Movie.where.not(rating: “PG-13”)
Movie.where.not(rating: [“PG”, “PG-13”])
Movie.where(“total_gross < ?", 50000000) Movie.where("released_on > ?”, Time.now)
Movie.where(“released_on <= ?", Time.now).order("released_on desc") To view SQL use to_sql: Movie.where(rating: "PG-13").to_sql To rollback last migration: rails db:rollback
Assets
To see assets: http://base_url/assets/asset_name
http://localhost:3000/assets/application.js

Validation
Active Record methods on an instance:
e.valid?
e.errors
e.errors[:name]
e.errors.full_messages
movie.errors.full_messages.to_sentence

Validation Examples:
validates :title, :released_on, :duration, presence: true
validates :description, length: { minimum: 25 }
validates :total_gross, numericality: { greater_than_or_equal_to: 0 }

validates :image_file_name, allow_blank: true, format: {
with: /\w+\.(gif|jpg|png)\z/i,
message: “must reference a GIF, JPG, or PNG image”
}
RATINGS = %w(G PG PG-13 R NC-17)
validates :rating, inclusion: { in: RATINGS }
movie.errors.full_messages.to_sentence

Controllers
To run something before each action:
before_action :method_name

Flashes
One time messages.
To set:
flash[:notice] = “Message!”
If in redirect, can do:
redirect_to some_url, alert: “Alert!”
To read in view:
<%= flash[:notice] %>

Custom Flashes with redirects:
Rails only supports :notice and :alert by default for redirects. To add a custom one, add this to your ApplicationController: add_flash_types(:danger)

Gemfile
To set gems for specific environment:
group :development, :test do
gem ‘sqlite3’
end
To install gems excluding a group:
bundle install –without production

Nested resources
resources :parents do
resources :children
end