Rails Active Storage + AWS Rekognition: How to get IO file - ruby-on-rails

Question

I'm trying to integrate AWS Rekognition into my Rails app. After the user uploads his avatar via Active Storage, Rekognition should show some info about it.
def update
respond_to do |format|
if #user.update(user_params)
if #user.images.attached?
Aws.config.update({
region: 'us-west-2',
credentials: Aws::Credentials.new('ACCESS_KEY', 'SECRET_KEY')
})
rekognition = Aws::Rekognition::Client.new(region: Aws.config[:region], credentials: Aws.config[:credentials])
img = #user.images.first. # original was: File.read(ARGV.first)
#detect faces
resp = rekognition.detect_faces({
image: { bytes: img },
attributes: ["ALL"], # What attributes to return
})
resp.face_details[0].emotions.each do |emo|
puts emo.type + " " + emo.confidence.to_i.to_s #=> Strings "HAPPY", "SAD", "ANGRY"
end
end
end
end
However, I get the error
expected params[:image][:bytes] to be a String or IO object, got value #<ActiveStorage::Attachment id: 4, name: "images", record_type: "User", record_id: 47, blob_id: 9, created_at: ""> (class: ActiveStorage::Attachment) instead.
How can I get the image file property into AWS Rekognition?

Answer 1

There is two way to pass image to Aws::Rekognition.
AWS S3 image url and name
resp = rekognition.detect_faces(
{image:
{s3_object:
{bucket: `bucket name`,
name: `pull path of file`,
},
}, attributes: ['ALL'],
}
)
Via Image object
rekognition.detect_faces({
image: { bytes: File.read(`path of file`) }
})
in your case you are passing ActiveStorage object that can't parse by AWS. that's why it throw error.