Sample App: CarrierWave Multiple File Upload

This app demonstrates an example of how to use the CarrierWave gem to facilitate multiple file uploads. This is a Rails 3.2.3 application that uses Ruby 1.9.3 and was developed on Mac Lion OS X.

CarrierWave is easy to set up and by default allows just one file to be uploaded at a time. To upload more than one file at a time, I’ve made use of the Jquery-File-Upload plugin. This plugin expects a json response and uses AJAX to update the page with the upload results. To facilitate the creation of a json response, I use the Jbuilder gem.

The example here has two models, Gallery and Photos. Gallery has many Photos. Photo belongs to Gallery. Since these two models are nested, I took the nested resources approach.

Since we’re uploading image files, we’ll want to use a gem called MiniMagick which is a Ruby wrapper for ImageMagick. Use HomeBrew to install ImageMagick: brew install imagemagick.

One side note regarding Carrierwave: when photos are deleted, the corresponding file folders become empty, but are not removed. This is a Carrierwave “feature”, and work-arounds can be found online. Paperclip, another popular upload gem cleans up its folders nicely and is easy to use as well.