How to write to tmp file or stream an image object up to s3 in ruby on rails - ruby-on-rails

Question

The code below resizes my image. But I am not sure how to write it out to a temp file or blob so I can upload it to s3.
origImage = MiniMagick::Image.open(myPhoto.tempfile.path)
origImage.resize "200x200"
thumbKey = "tiny-#{key}"
obj = bucket.objects[thumbKey].write(:file => origImage.write("tiny.jpg"))
I can upload the original file just fine to s3 with the below command:
obj = bucket.objects[key].write('data')
obj.write(:file => myPhoto.tempfile)
I think I want to create a temp file, read the image file into it and upload that:
thumbFile = Tempfile.new('temp')
thumbFile.write(origImage.read)
obj = bucket.objects[thumbKey].write(:file => thumbFile)
but the origImage class doesn't have a read command.
UPDATE: I was reading the source code and found this out about the write command
# Writes the temporary file out to either a file location (by passing in a String) or by
# passing in a Stream that you can #write(chunk) to repeatedly
#
# #param output_to [IOStream, String] Some kind of stream object that needs to be read or a file path as a String
# #return [IOStream, Boolean] If you pass in a file location [String] then you get a success boolean. If its a stream, you get it back.
# Writes the temporary image that we are using for processing to the output path
And the s3 api docs say you can stream the content using a code block like:
obj.write do |buffer, bytes|
# writing fewer than the requested number of bytes to the buffer
# will cause write to stop yielding to the block
end
How do I change my code so
origImage.write(s3stream here)
http://docs.aws.amazon.com/AWSRubySDK/latest/AWS/S3/S3Object.html
UPDATE 2
This code successfully uploads the thumbnail file to s3. But I would still love to know how to stream it up. It would be much more efficient I think.
#resize image and upload a thumbnail
smallImage = MiniMagick::Image.open(myPhoto.tempfile.path)
smallImage.resize "200x200"
thumbKey = "tiny-#{key}"
newFile = Tempfile.new("tempimage")
smallImage.write(newFile.path)
obj = bucket.objects[thumbKey].write('data')
obj.write(:file => newFile)

Answer 1

smallImage.to_blob ?
below code copy from https://github.com/probablycorey/mini_magick/blob/master/lib/mini_magick.rb
# Gives you raw image data back
# #return [String] binary string
def to_blob
f = File.new #path
f.binmode
f.read
ensure
f.close if f
end

Answer 2

Have you looked into the paperclip gem? The gem offers direct compatibility to s3 and works great.