Category Archives: Ruby On Rails

Rails – jQuery generating extra HTML headers after AJAX call

May 24, 2017 12:54 pm /

If you get the following extra HTML headers after using the jQuery AJAX method on a page and immediately clicking on another link:

0
HTTP/1.1 200 OK
Cache-Control: no-cache, no-store, must-revalidate
Pragma: no-cache
Expires: 0
Content-Type: text/html; charset=utf-8
X-UA-Compatible: IE=Edge
Transfer-Encoding: chunked

Tracing back to my webapp, it looks like the error was due to jQuery expecting a callback from my Rails AJAX method. It times out automatically after a few seconds, but if you click on another link immediately after it will generate additional HTML headers. To fix this, I added a new response to the script as a JSON.

In my Rails app, I added the following line to the corresponding method in the controller:
render json: nil, status: :ok

Ruby 3+

I didn’t have to make any additional changes on the jQuery script. The following worked for me without any issue:
$.ajax({
url : "/myapp/myajaxscript",
type: "POST",
data : formData,
success: function(data,status)
{
console.log(status);
}
});

Posted in: AJAX, jQuery, Ruby on Rails

Permit nested attributes in Rails 4

November 2, 2015 6:33 pm /

In order to use nested attributes in Rails 4, one must use the params.require method inside controller with the _attributes keyword and the list of fields inside the nested model. This is a good option if the keys of the nested models are known.

Here’s a simplified version of what it would look like. The question_params method inside the controller will have the nested model answer setup with answer_attributes: [:id, :response].

/controllers/question_controller.rb

class QuestionController > ApplicationController
  def new
    if params[:question].present?
      @question = Question.new(question_params)
    else
      @question = Question.new
    end
  end

private
  def question_params
    params.require(:question).permit(:id, :name, answer_attributes: [:id, :response])
  end
end

 

/models/question.rb

class Question > ActiveRecord::Base
has_many :answers
  accepts_nested_attributes_for :answers
end

/models/answer.rb

class Answer > ActiveRecord::Base
  belongs_to :question
end

Note: If you want to whitelist all nested parameters, you can use the code at: https://github.com/rails/rails/issues/9454#issuecomment-14167664. This would eliminate the need to list each of the nested models individually.

Posted in: Ruby on Rails / Tagged: ,

Custom OmniAuth Callback URL

August 18, 2015 6:42 pm /

If you have Ruby on Rails App and want to use a custom OmniAuth Callback URL (Something other than /auth), there is a configuration value that you can set.

/config/initializers/omniauth.rb

Rails.application.config.middleware.use OmniAuth::Builder do
provider :twitter, {
 :callback_path => "/myauth/shibboleth/callback"
}
end

Replace “myauth” with the path that you prefer to use. This will allow for a different callback URL when users aren’t logged in. Tested with Rails 4.2 and Ruby 2.2.

Posted in: Ruby on Rails / Tagged:

Fix: LoadError: no such file to load — mysql2/mysql2 with jRuby and Warbler

August 7, 2013 12:03 pm /

I recently transitioned a Ruby on Rails Passenger server to jRuby with Tomcat and encountered an error caused by the Gemfile.

“no such file to load — mysql2/mysql2
LoadError: no such file to load — mysql2/mysql2”

The fix? JRuby needs a MySQL adapter named “activerecord-jdbcmysql-adapter” in order to it to work properly.

# Original MySQL Adapter --
# gem 'mysql2', '~>0.3.13'
#
# New Adapter for jRuby
gem 'activerecord-jdbcmysql-adapter'

Adding the ‘activerecord-jdbcmysql-adapter’ gem and commenting out the original “mysql2” gem fixed the issue. I recommend using the “warble executable war” to troubleshoot these errors since you can quickly run a “java -jar myapp.war” to test it out.

Tested with jRuby 1.7.4, Rails 3.2.12

Posted in: Ruby on Rails / Tagged: , ,

Installing Phusion Passenger 4.0 with SELINUX and Apache on RHEL 6.3

April 3, 2013 12:54 pm /

Installing Phusion Passenger 4 with SELINUX enabled is quite a challenge, especially with the lack of documentation out there with the latest version of Passenger.

Installation Notes:

Follow the following guide: http://www.seifeet.com/2012/09/ruby-apache-on-centos-63.html. This will get you 90% of the way there.

There are a few changes that I needed to make to get it working properly with my app.

Set the passenger temp folder to /var/run/rubygem-passenger instead of /tmp/ in the Apache config.  (/etc/httpd/conf.d/passenger.conf)

PassengerTempDir /var/run/rubygem-passenger

The reason behind this is due to the SELINUX permissions on the parent /tmp folder will not work properly. If you don’t have the PassengerTempDir set in Apache, you will get an error of a temp folder not being set when running “grep httpd /var/log/audit/audit.log | audit2allow -M passenger“

Here’s the permissions I have for the rubygem-passenger folder:

rvm rvm system_u:object_r:httpd_var_run_t:s0 rubygem-passenger

Set the permissions of the /myrailsapp/tmp folder

If you are using compiled CSS libraries such as Compass, you will need to set the proper SELINUX permissions for the compiled assets folder. Otherwise, any changes to the compiled css files will cause a fatal error in your application (read failure in the tmp folder). 

chcon -R -t httpd_sys_rw_content_t tmp

Sample Passenger configuration file for Apache (/etc/httpd/conf.d/passenger.conf)

LoadModule passenger_module /usr/local/rvm/gems/ruby-2.0.0-p0/gems/passenger-4.0.0.rc4/libout/apache2/mod_passenger.so

PassengerRoot /usr/local/rvm/gems/ruby-2.0.0-p0/gems/passenger-4.0.0.rc4
PassengerRuby /usr/local/rvm/wrappers/ruby-2.0.0-p0/ruby

PassengerDefaultUser rvm
PassengerDefaultGroup rvm

PassengerLogLevel 2
PassengerDebugLogFile /var/log/httpd/passenger.log

PassengerPreStart [YOUR SITE URL]
PassengerMaxPoolSize 2
PassengerPoolIdleTime 300
PassengerTempDir /var/run/rubygem-passenger

Still having issues with the install? Here’s some fixes:

Error:  Cannot stat ‘/var/run/rubygem-passenger/passenger.1.0.19162’: Permission denied
Fix: This is due to SELINUX blocking access to the folder. Run the “grep httpd /var/log/audit/audit.log | audit2allow -M passenger” after changing setenforce to 0, restarting httpd, and adding the policy via semanage -i passenger.pp.

Error: Cannot change the directory ‘/tmp/passenger.1.0.—/generation-0/buffered_uploads’ its UID to 48 and GID to 48
Fix: This is a regular user permission issue (User/Group needs to have write permissions) and is also related to not using /var/run/rubygem-passenger

Error: Errno::EACCES Permission Denied
Fix:  Your /[myrailsapp]/tmp folder permissions is incorrect. Compiled CSS libraries use the /[myrailsapp]/tmp folder to save all the data  This could be either the user/group permissions or the SELINUX. The fastest way to check to see if its a SELINUX issue is setting setenforce to 0 and restarting httpd. If the app works, then you will need to set the /[myrailsapp]/tmp folder permissions. If not, check to see that the folder has global read/write permissions.

 

Posted in: Ruby on Rails / Tagged: , ,

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