Image Upload Using Rails API and Paperclip

September 27, 2014

I am working on a mini-project with my friends and part of it requires us to make a RESTful API. We opted to use Ruby on Rails for the backend since we have a tight schedule and using this stack would simplify the development. For my first task, I need to create an endpoint which will allow me to upload an image together with the object’s properties.

I used Paperclip to help manage the image file. I was stumped on how to accomplish this task for a while because this was the first time I’d be writing an endpoint that allowed me to upload an image. After researching for a while, I saw this blog which showed me how to upload a file.

The main idea is to encode the file to Base64, and set the correct attributes (content-type, filename) so we can parse it in the server-side correctly.

A sample request would look something like this:


Request Payload:

      filename: "original_filename.jpg",
      content: "<Base64Encoded data>",
      content_type: "<image content type>" # e.g. image/jpeg

Your controller should be able to process this.

class API::V1::ItemsController < ApplicationController

  def create
    result = { status: "failed" }

      params[:image] = parse_image_data(params[:image]) if params[:image]
      item = Item.new
      item.image = params[:image]

      if item.save
        result[:status] = "success"
    rescue Exception => e
      Rails.logger.error "#{e.message}"

    render json: result.to_json

  # This part is actually taken from http://blag.7tonlnu.pl/blog/2014/01/22/uploading-images-to-a-rails-app-via-json-api. I tweaked it a bit by manually setting the tempfile's content type because somehow putting it in a hash during initialization didn't work for me.
  def parse_image_data(image_data)
    @tempfile = Tempfile.new('item_image')
    @tempfile.write Base64.decode64(image_data[:content])

    uploaded_file = ActionDispatch::Http::UploadedFile.new(
      tempfile: @tempfile,
      filename: image_data[:filename]

   uploaded_file.content_type = image_data[:content_type]

  def clean_tempfile
    if @tempfile

So there you have it, a controller that handles image upload.

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