Skip unnecessary files while running Rails Generate

coderhs — Wed, 27 Jul 2016 04:27:04 +0000

rails generate controller Home Index new create, would create the following set of files: As one knows from experience, the helper; javascript and stylesheet files are not always used. In fact, most of the time, we would have a single stye.scss, and main.coffee that would take care of 95% of the total behaviour of our application. So, if we do not delete those files after generation, we would just end up with a lot of files in our system which would have no code throughout the life cycle of the program. Fortunately, rails gives us the ability to customize its own generators so that we can disable these files from being generated. Once we place the below code in the application.rb, it will stop the generation of these extra files.

config.generators do |g|
  g.helper false
  g.stylesheets false
  g.javascripts false
  g.view_specs false
end

Now, when you run rails generate controller Home Index new create, you will get less files. ]]>

Counter Cache: How to get started

coderhs — Tue, 26 Jul 2016 10:40:48 +0000

number of tasks under a project or the number of comments in a post or the number of users in an organization or anything similar is a common requirement in most rails applications. The code for doing it is also simple- @project.tasks.count; but the problem with this code is that every time you run it, you are counting the number of tasks of that project one by one. So, the speed of execution decreases with more number of rows. This code will slow down your page load, if you are displaying the details of more than one project in your page as shown below. To speed this up, rails gives you an in-build mechanism called “Counter Cache“. As the name suggests, it literally means to cache the number of referenced rows it has (number of tasks a project has). Example code definition

class Projects < ActiveRecord::Base
  has_many :tasks
end
class Task < ActiveRecord::Base
  belongs_to :project
end

To implement counter_cache, you need to pass in the counter_cache: true option along with the belongs_to relationship. You also need to add a migration to add an extra column called tasks_count to store the count. This needs to be added to the other model, which has the has_many reference.

class Task < ActiveRecord::Base
  belongs_to :project, counter_cache: true
end

Migration

class AddTasksCounterCacheToProjects < ActiveRecord::Migration[5.0]
  def change
    add_column :projects, :tasks_count, :integer
  end
end

If you are adding counter cache to an existing system, you need to update your tasks_count with the existing counts. To do that, one can use the code given below. Either place the code along with the migration or run it in console in both production/development environments.

Project.find_each { |project| Project.reset_counters(project.id, :tasks) }

Also note that the tasks_count is just the default column name; if you wish to change it with another name, just pass that name along with the :counter_cache option as below.

class Task < ActiveRecord::Base
  belongs_to :project, counter_cache: :not_the_default_column_name
end

Now, to use the counter cache in your calculations, you should use the method “size” instead of “count”. The method “size” will use the counter_cache if its present, where as using “.count” itself would do the actual sql count.

<% Project.all.each do |project| %>
  <%= project.name %> (<%= project.tasks.size %>)
<% end %>

Points to Remember

:counter_cache is the optional attribute of a belongs_to relationship
It requires the creation of an extra column (tasks_count) in the table which has the has_many relationship
One can use another column name by passing the name along with :counter_cache option
To use the counter_cache, one must use the “.size” method

Speed Improvements ]]>

tips – redpanthers.co

Skip unnecessary files while running Rails Generate

Counter Cache: How to get started