Category Archives: RailsTips

Asset Pipeline Development RailsTips

How to figure out Runtime Dependencies when using Bower via Rails Assets

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Recently, for one of our client projects we decided to make use of Bower via Rails Assets to better manage Javascript dependencies with respect to the application. This project is on Rails 4.0.13 . For reasons as to why we choose this approach one can refer to the below two blogs –

1. Better Asset Management in Rails Using Rails Assets

2. Bower through Rails Assets

In our application, we were basically replacing the existing dependencies(few of which were placed in vendor/assets/javascripts and others were gems like the jquery-ui-rails) with gems provided to us via the Rails Assets site.

One such third party plugin that we had to replace was the jquery validate plugin. After including the appropriate gem(rails-assets-jquery-validate) from rails-assets site in the gemfile and running bundle to install that gem you might observe from the Gemfile.lock that this gem depends on the rails-assets-jquery-gem.

The BIG question now is, how does the rails-assets-jquery-validate gem(I had installed the gem with version 1.13.1) know which version of the rails-assets-jquery gem it should pick up, given that unlike the current rails-assets site(based on the screenshot below) doesn’t currently list the runtime dependencies required for a gem(which in our case is that we can’t directly find the runtime dependencies for rails-assets-jquery-validate gem).

The workaround

One can find out the exact dependencies required wrt a specific gem by checking out the bower.json file with respect to appropriate code repository corresponding to the gem(in the context of our e.g., this would be for checking out the bower.json file of the rails-assets-jquery-validate gem related code repository) listed on the rails assets site.



Creating Your First Gem is Easy…

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Many of us used of so many gems in ruby, so lets try to create a basic gem.
Simple, We just have to generate two files to create your own gem.

Step1: Create a gemspec.
Create a gemspec file inside root directory, file-name should be same as your gem name (Eg: In our case its greeting_gem.gemspec)

– Specify your gem specifications

Step2: Add some code.
Create a greeting_gem.rb file in lib folder

Step 3: Generate gem file.

This command will build the gem, which can be used in another ruby program.

Step 4: Test the gem.
gem install greeting_gem, to install the gem locally to test it out.
open irb
>> require ‘greeting_gem’
=> true
>> GreetingGem.greeting(‘sravani’)
Hello sravani

Isn’t it simple!
Add as many methods you want in the same way and move on to bigger things.

ProgrammingTips RailsTips

RailsTip: Setting boolean values in ActiveRecord callbacks

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I realized the importance of reading documentation clearly and with care, when I spent hours debugging this stupid problem.

This is an Active Record callback in action. We are setting a boolean field ‘approved’ to false in the before_create ActiveRecord callback.

This code is simple, straightforward and looks flawless, until you see a ActiveRecord::RecordNotSaved exception when you try to create a Topic. Our only savior, the errors object also doesn’t give us any information on what went wrong.

Two important things we always forget and aren’t quite obvious are

1. Implicit return values in Ruby. This feature always returns the value of the last executed statement in a method or block.

2. If an ActiveRecord callback returns false, all the later callbacks and the associated action are cancelled.

In our example, the statement ‘self.approved = false’ returns false and since that is the last statement executed in the callback, the callback returns false which cancels the create operation.

So, the best way to set boolean values in an ActiveRecord callback is