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Introducing Has Face for Rails

Posted in Code, Ruby on Rails, Tips and Tricks

Have you ever created an application where users are trusted to upload their own avatars? Wouldn’t it be great if there was an easy way to ensure the avatar contains a person’s face?

Has Face is a neat little gem that uses the API to ensure that an image contains a persons face. It’s very simple to use and can be easily integrated into an existing rails application.

To get started add the has_face gem to your Gemfile and run a bundle install

Can’t see this Gist? View it on Github!

Run the generator to copy over an initializer:

Can’t see this Gist? View it on Github!

The initializer should look something like this:

Can’t see this Gist? View it on Github!

Now we’ll need to make a developer account. You can signup for a free account over at Once you have signed up, place your API key and API secret in the initializer config.

The last option in the initializer (skip_validation_on_error) will change the behavior of has_face when an error occurs. If set to true, when an error occurs a warning will be logged to the logfile with detailed information about the failure and face validation will be skipped. This can be useful if you want your application to function if the API service is not reachable. If the value is false then an exception will be raised when an API call fails, this will allow you to manually handle the exception yourself, please check the documentation for details on the errors raised.

Once the initializer settings are setup then we can add face validation to a model. In the example below I’m using carrierwave to attach the image to the model but other image attachment gems should also work fine (anything that correctly responds to `path` should be OK).

Can’t see this Gist? View it on Github!

That’s it, that’s all we need to have a functioning face validator. There are a few other options that I haven’t covered here in this short guide, please consult the readme for more detailed information.

RSpec 2.6.0 and RCov

Posted in Code, Ruby on Rails, Tips and Tricks

Just upgraded to the newest RSpec (2.6.0) and found that RCov has stopped working completely? That’s what happened to me after running a bundle update. RCov refused to run, no error messages, just blank output.

After looking around for a little while I found this:

In short: the new RSpec has been broken up into modules a tad more, the one that we require for rspec to run correctly ‘autorun’ is not included by default, so to solve this simply add require ‘rspec/autorun’ to the top of your spec_helper.

Can’t see this Gist? View it on Github!

Sending Apple Push notifications in rails with Redis and apn_sender

Posted in Code, Inside TFG, Ruby on Rails, Tips and Tricks

Sending iOS push notifications from a Rails application is very easy to do these days, thankfully there are many great Ruby gems that can be used to handle most of the magic for you. Recently I ran into the apn_sender gem which handles sending push notifications in a really neat way.

Sending push notifications directly from a Rails application can be slow and we probably don’t want to have the user waiting until the notification is sent, instead apn_sender can be setup to run a worker which is constantly connected to the apple push notification service. When there are new notifications to send, the notifications are queued up and sent through the always open connection that is maintained by the worker.

apn_sender uses redis as a message queue to keep track of the notifications waiting to be sent, you’ll need to install it before using the gem.

To add apn_sender in your Rails 3 application, just add the gem to your Gemfile. We’re going to need the daemons gem too so we’ll include that as well.

Can’t see this Gist? View it on Github!

Now we can create our daemon which we will be using for sending push notifications, this can be placed anywhere, I’ve put mine in script/apn_sender. Make sure to add execute permission to the file after creating so we can run it.

Can’t see this Gist? View it on Github!

Before the daemon can start running we’ll need to put our iOS push certificate into the application. Instructions for generating the certificates are available at the Apple Developer site. The certificates need to be placed inside of /config/certs and should be named apn_development.pem or apn_production.pem for production.

Once the certificates are in their correct locations, we can start up the daemon. The daemon does not know about the Rails environment so we need to specify this when starting it up. The daemon supports start, stop and restart commands. There is a verbose flag available to output more information (which can be helpful when debugging).

Can’t see this Gist? View it on Github!

Our application is now set up to send push notifications, this can now easily be performed by adding a new notification to the queue. The notify method on the APN class will take a push notification token and then our parameters, we can specify the alert message to show the user, whether or not we want sound as well as the number to display on the badge icon. Anything else we pass to notify will be sent as metadata in the push notification. Here’s an example of creating a notification.

Can’t see this Gist? View it on Github!

The worker should pick up the notification within a few seconds and send it off. The apn_sender has many other features that I haven’t covered, you can view the full documentation over at

Adding additional processing support to CarrierWave

Posted in Code, Inside TFG, Ruby on Rails, Tips and Tricks, Websites or Tools

CarrierWave is a great gem for adding image uploading and basic processing abilities to your Rails applications. By default there is no way to set the quality of the resized images, which could be a very useful feature.

One of the applications that we’re currently building has a requirement to resize and compress images to produce smaller file sizes, as well as stripping out any personal information that may be stored in the uploaded images.

Out of the box CarrierWave provides a consistent interface to process images using RMagick, MiniMagick or ImageScience. Resizing and cropping is supported for all three image processing engines but setting the quality or removing personal data is not supported. Thankfully, CarrierWave provides an easy way to extend the default functionality so we can do more.

For the examples I’ll be adding extra functionality to RMagick processing. If you’re using MiniMagick or ImageScience the methods will need to be altered to work correctly. We’ll start by adding a new initializer into our application.


You may be wondering about the fix_exif_rotation method. Well, some modern cameras always take photos upright, in portrait. When you take a photo in landscape mode the photo is actually saved as a portrait, but the photo will contain some extra orientation metadata. When we remove the embedded data in the photo this value gets removed, so as a result we need to manually rotate the photo, which is what this method does.

The application server will need to be restarted before the new initializer can be used. Once restarted the new filters can be used in an uploader like so:


That’s it! That’s all that’s needed to add extra quality and processing functionality to carrierwave.

Highlighting the selected navigation item in Serve

Posted in Inside TFG

We’re using Serve at work for a static public facing website and needed to highlight the currently displayed navigation item.

After some experimenting we got this:

  - page = request.path.split('/').last || 'index-page'

You grab everything in the path after the last slash. If there’s no path set (so for the index page) it will use whatever we set, above i’ve just used ‘index-page’ as an example.

You can now attach that variable anywhere you’d like, I usually attach it to the body like so

%body{:class => page}

Then make sure the navigation has matching classes. So for example if my pages hare URL’s of /about and /home/contact, the navigation list would like like:

    <li class="about"><a href="/about"></li>
    <li class="contact"><a href="/home/contact"></li>

We can use those two classes to set styles when they match up:

body.about li.about a, a {
    // set style here!

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