9 Best Practices to Follow While

摘自 https://dzone.com/articles/9-best-practices-to-follow-while-coding-in-rails-1

1. Caching With Instance Variable

# Bad Practice
class Project < ActiveRecord::Base
  belongs_to :creator, :class_name => “User”
  def company
    creator.company
  end
end

# Good Practice
class Project < ActiveRecord::Base
  belongs_to :creator, :class_name => “User”
  def company
    @company ||= creator.company
  end
end

2. Use Local Variables in Place of Instance Variables in Partials

# Bad Practice
<%= render :partial => 'header' %>

# Good Practice
<%= render :partial =>  'header', :locals => {:project => @project}%>

3. Prevent SQL Injection

# Bad Practice
User .where(“name = #{params[:name]}“)

# Good Practice
User.where(“name = ?”, params[:name])
User.where(:name => params[:name]

4. Avoid the n+1 Problem

# Bad Practice
@users = User.limit(50)

# Good Practice
@users = User.includes(:house).limit(50)

5. Follow The Law of Demeter

# Bad Practice
class Project < ActiveRecord::Base
  belongs_to :creator
end

<%= @project.creator.name %>
<%= @project.creator.company %>

# Good Practice
class Project > ActiveRecord::Base
  belongs_to :creator
  delegate :name, :company, :to => :creator, :prefix => true
end

<%= @project.creator_name %>
<%= @project.creator_company %>

6. Declare Instance Variables Inside the Action

# Bad Practice
before_filter :get_project

def show
  @tasks = @project.tasks
end

private

def get_project
  @project = Project.find(params[:id])
end

# Good Practice（有疑惑，我们都是用上面的 XD）
def show
  @project = get_project
  @tasks = @project.tasks
end

private

def get_project
  Project.find(params[:id])
end

7. Use Lambda in Scopes

# Bad Practice
scope :recent, where('starting_date > ?', 1.day.ago)
=>

where('starting_date > ?', '02-10-2013 20:00')
where('starting_date > ?', '02-10-2013 20:00')

# Good Practice
scope :recent, lambda{ where('starting_date > ?', 1.day.ago)}
=>


where('starting_date > ?', '02-10-2013 20:00')
where('starting_date > ?', '03-10-2013 21:23')

8. Use ? At the End of Method Name If It Is Returning Boolean Value

# Bad Practice
def exist 
end

# Good Practice
def exist?
end

9. Make Helper Methods for Views

# Bad Practice
<%= f.select( :category, ['Australia', 'Belgium', 'Canada', 'China', 'India', 'Malaysia', 'Switzerland'].collect{|country| [country, country]}) %>

# Good Practice
<%= f.select( :category, country_names.collect{|country|  [country, country]}) %>

def  country_names
    ['Australia', 'Belgium', 'Canada', 'China', 'India', 'Malaysia', 'Switzerland']
end

# Bad Practice
<% case @filter %>
<% when 'inbox' %>
  <%= render 'inbox'%>
<% when 'sent' %>
  <%= render 'sent' %>
<% when 'draft' %>
  <%= render 'draft' %>
<% when 'trash'%>
  <%= render 'trash' %>
<% end %>

# Good Practice
<%= render filter_templates(@filter) %>

def filter_templates(filter)
  case filter
  when 'inbox'
    render 'inbox'
  when 'sent'
    render 'sent'
  when 'draft'
    render 'draft'
  when 'trash'
    render  'trash'
  end
end