Rails 4.2 - Send Image Data as Email Attachment Without Saving Image

Question

My client app is an iOS app written in Swift. In that iOS app, I convert an image to a Base64 encoded String and then send this String to my Rails server in the body of an HTTP request. This is my code for doing so:

// Create a new URL request with the URL
let request: NSMutableURLRequest = NSMutableURLRequest(URL: url)

// Set the HTTP method to POST
request.HTTPMethod = "POST"

// Set the content type of the request to XML
request.setValue("application/xml", forHTTPHeaderField: "Content-Type")

// Convert the image to binary and then to a Base 64 Encoded String
let imageData:String = UIImagePNGRepresentation(image).base64EncodedStringWithOptions(nil)

// Set the HTTP Body of the request to the image
request.HTTPBody = NSData(base64EncodedString: imageData, options: nil)

In my Rails controller handling the request, I would like to retrieve the image and send it as an email attachment. I do NOT want to save the image anywhere; I just want to decode the image in memory and then somehow use that as the email attachment.

How can I retrieve the image data in my Rails controller and decode it in a way that would allow me to send it back as an email attachment?

To retrieve the image data, I've tried using request.body.read , but this returns an empty String for some reason.

Thanks in advance for any help!

EDIT:

request.body.read was returning an empty String because I used a GET request. I've since learned that it's not a good idea to send an HTTP Body in a GET request, so I changed the method to POST. Now request.body.read is returning my encoded String! I've also added the Content-Type header to the request.

Still, I can't figure out how to properly decode the HTTP Body and assign it to an image object of some sort.

EDIT #2:

I've managed to send the email attachment in my mailer using the following code:

attachments["file.png"] =
{
   mime_type: 'image/png',
   content: Base64.decode64(request.body.read)
}

Unfortunately, the PNG file cannot be opened when I receive it in the email. I don't know if the encoding translates well from Swift to Ruby. I'll keep investigating.

EDIT #3:

I removed the Base64 String encoding, and it's working great! See my posted answer below.

Answer 1

I figured it out! I think the Base64 encoding/decoding isn't performed the same way on Swift and Ruby, so I decided to send the image as NSData without String encoding and then send it back, and that worked! Here is my final code:

Swift

// Create a URL
let url:NSURL = NSURL(string: urlString)!

// Create a new URL request with the URL
let request: NSMutableURLRequest = NSMutableURLRequest(URL: url)

// Set the HTTP method to POST
// GET requests usually do not have an HTTP Body, and it's considered a very bad idea to include one in a GET request
request.HTTPMethod = "POST"

// Set the content type of the request to XML
request.setValue("application/xml", forHTTPHeaderField: "Content-Type")

// Convert the image to binary data
let imageData:NSData = UIImagePNGRepresentation(image)

// Set the HTTP Body of the request to the image
request.HTTPBody = imageData

// Create a new queue
let queue:NSOperationQueue = NSOperationQueue()

// Send the async request
NSURLConnection.sendAsynchronousRequest(request, queue: queue, completionHandler:
{ (response:NSURLResponse!, data:NSData!, error:NSError!) -> Void in
    println(response)
})

You can put this code in any method.

Ruby on Rails (Ruby 2.1.1 and Rails 4.2.0)

class ImageApiController < ApplicationController
  # Skip verifying the authenticity token since a form wasn't submitted; a web request was sent
  skip_before_filter :verify_authenticity_token, :only => [ :index ]

  def index
    params[:image] = request.body.read

    # Send the email
    UserMailer.image_attachment_email(params).deliver_now

    respond_to do |format|
      format.html
      format.js  { render plain: "Test" }
      format.xml { render plain: "Test" }
    end
  end
end

Then in UserMailer:

class UserMailer < ApplicationMailer
  def image_attachment_email(params)
    attachments["image.png"] =
    {
      mime_type: 'image/png',
      content: params[:image]
    }

    # Send an email
    mail(to: "user@example.com", subject: "Image")
  end
end

So actually no Base64 String encoding was needed. This code works great!