Rails 5.2 ActiveStorage save and then read Exif data - ruby-on-rails

Question

On Rails 5.2 I am trying to save an avatar via ActiveStorage but it seems as though not image oriantation data is being saved in the active storage blob.
I am saving the avatar via a file_field on a create action my
#user model
has_one_attached :avatar
private
def avatar_validation
if avatar.attached?
if avatar.blob.byte_size > 1000000
avatar.purge
errors.add(:avatar, 'file is too large')
elsif !avatar.blob.content_type.in?(%w[image/png image/jpg
image/jpeg])
avatar.purge
errors.add(:avatar, 'file type needs to be JPEG, JPG, or PNG')
end
end
end
I have been reading some documentation for minimagick https://github.com/minimagick/minimagick but have not figured out how I can associate
user.avatar.blob
with
image = MiniMagick::Image.open("input.jpg")
I have tried
image = MiniMagick::Image.open("user.avatar.blob")
but have had no luck
I need to try and figure this out because some avatars stored in active storage are being displayed rotated 90 degrees.
https://edgeguides.rubyonrails.org/active_storage_overview.html
talks of image processing but I have also had no luck with the gem rails recommends

Answer 1

I think you want to use a variant when displaying the image rather than trying to edit the stored image. To fix the orientation, you could say:
user.avatar.variant(auto_orient: true)
And if you want to do several operations at once (rather than in a pipeline), use combine_options:
user.avatar.variant(combine_options: {
auto_orient: true,
gravity: 'center',
resize: '23x42', # Using real dimensions of course.
crop: '23x42+0+0'
})
The edited image will be cached so you only do the transformation work on first access. You might want to put your variants into view helpers (or maybe even a model concern depending on your needs) so that you can isolate the noise.
You might want to refer to the API docs as well as the guide:
ActiveStorage::Variant
ActiveStorage::Variation