Photo metadata is nil until after AR callbacks have run

[kris]

Describe the bug in a sentence or two.

I'm trying to extract colors from an uploaded image, following the docs on utilizing cloudinary_transformation and an after_save on the model. Unfortunately, metadata seems to always be nil. Once the after_save callback has finished, then source.metadata is populated. This seems like a misplaced lifecycle callback or something.

Issue Type (Can be multiple)

• [ ] Build - Cannot install or import the SDK
• [ ] Performance - Performance issues
• [x] Behaviour - Functions are not working as expected (such as generate URL)
• [x] Documentation - Inconsistency between the docs and behaviour
• [ ] Other (Specify)

Steps to reproduce

class PhotoUploader < CarrierWave::Uploader::Base
  include Cloudinary::CarrierWave
  cloudinary_transformation image_metadata: true, colors: true
end

class Photo < ApplicationRecord
  mount_uploader :source, PhotoUploader

  after_save :extract_colors

  def extract_colors
    # `source.metadata` is `nil`
  end
end

Environment and Libraries (fill in the version numbers)

• Cloudinary Ruby SDK version - 1.23.0
• Ruby Version - 3.1.2
• Rails Version - 7.0.4
• Carrierwave - 2.2.2

[tommyg-cld]

@kris I just tested this and I'm unable to replicate it, I'm basically using the photo_album sample from https://github.com/cloudinary/cloudinary_gem/tree/master/samples and I just modified image_uploader to

class ImageUploader < CarrierWave::Uploader::Base
  include Sprockets::Rails::Helper

  include Cloudinary::CarrierWave
  
  process :tags => ["photo_album_sample"]
  process :convert => "jpg"
  cloudinary_transformation :image_metadata => true, :colors => true

  version :thumbnail do
    eager
    resize_to_fit(150, 150)
    cloudinary_transformation :quality => 80          
  end 

end

And photo model to

class Photo < ActiveRecord::Base
  belongs_to :album

  mount_uploader :image, ImageUploader

  validates_presence_of :title, :image

  after_save :extract_colors

  def extract_colors
    if self.image.present? && self.image.metadata.present?
      exif = self.image.metadata["image_metadata"]
      colors = self.image.metadata["colors"]
    end
  end
end

Can you try like that?

[kris]

@tommyg-cld Sorry for the late reply. It still doesn't work. Try this:

1. Add a binding.pry in #extract_colors
2. Check image.metadata -- for me it's nil
3. Exit pry
4. Now check object.image.metadata and you will see it's set. The problem is that metadata appears to be nil until after the after_save is called.

[tommyg-cld]

@kris sorry for the delay. So yes after_save needs to be called so that the object is created first. Once the object is created, you can then access image.metadata.

Can you explain what exactly you are trying to achieve?

[kris]

@tommyg-cld When an image is uploaded, I wanted to have a callback that is triggered on the model to cache the extracted colors from Cloudinary. I was hoping to do this within a callback, but my current solution is to have an operation/service that saves the object, then updates the objects color cache via the mounted image, then call again. Less than ideal compared to an after_save, but I guess this is as good as I'll get.

[tommyg-cld]

@kris can you just not use after_save then?

[kris]

@tommyg-cld metadata is nil for me in after_save. I'll create a repo over the next few days to demonstrate.

[tommyg-cld]

@kris just following up to check if this is still an issue?