Convert file upload contents to a binary file without saving (Rails)

Question

I have a rails 3 app where I am using the 'face' gem to reference the Face.com API. The api method takes a parameter of the form:

:file => File.new(path_to_file, 'rb')

which works.

I am trying to change the flow of the app so that the file can be uploaded via a form, do some work with RMagick and then make the API call, all without saving the file to disk.

I can generate the RMagick 'Image' with

image = Magick::Image.from_blob(upload_image_field.read)

I can then manipulate the file with RMagick and even save the results into the database with:

self.data = image.to_blob #normally 'upload_image_field.read' if not using RMagick

My problem is that I can't change the image file (or the blob) into something that the API will recognize (without saving it to disk and then referencing the file on disk).

For example using this in the API method fails:

:file => image.to_blob

How do I convert he blob into the same format as

File.new(path_to_file, 'rb')

Thanks

JP Richardson · Accepted Answer · 2011-08-17 11:24:37Z

1

OK, I could be wrong on this one... but I wanted to dig this up. Unfortunately, you just have to live with saving it as a file. The reason is because the API makes an HTTP POST. Unfortunately, this needs to be a file.

References from: [https://github.com/rociiu/face/tree/master/lib/face]:

recognition.rb:

def faces_detect(opts={})
    opts.assert_valid_keys(:urls, :file, :detector, :attributes, :callback, :callback_url)
    make_request(:faces_detect, opts)
end

utils.rb:

def make_request(api_method, opts={})
   ....
    response = JSON.parse( RestClient.post(API_METHODS[ api_method ], opts.merge(api_crendential)).body )
   ....
  end

So, why is it a problem to save to a file then?

answered Aug 17, 2011 at 11:24

JP Richardson

39.6k36 gold badges123 silver badges152 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

CHsurfer Over a year ago

I was trying to eliminate extra writes to the hard drive.

JP Richardson Over a year ago

I figured. Could you write to a ramdrive to increase performance?

CHsurfer Over a year ago

Honestly, I have no idea. It would probably be easier for me to roll my own Face.com api which does it with post data.

CHsurfer Over a year ago

OK, so finally the ramdrive idea was really easy and that's what I am using now. Thanks!

Wedge Martin Over a year ago

This blows my mind. I was wondering why there weren't any examples showing up of using blob data in memory for rmagick transforms...

Collectives™ on Stack Overflow

Convert file upload contents to a binary file without saving (Rails)

1 Answer 1

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related