Handling images in rails 5 - ruby-on-rails

Question

I'm developing a api applicacion with Rails 5. From client side I have an Anuglar app.
I have the following requirements to do:
Async upload of images. (Note that implies that the images have no attached to a model at the first time).
The model to be create can have N images attached.
For each uploaded image, create M specified thumbnails. (Note that also that thumbnails should be attached to the model.)
I have read about CarrierWave and paperclip but I don't found how can I do all of these requirements.
I will really appreciate any suggestion, lib, gem, etc that covers all of these requirements.

Answer 1

I have implemented something similar with CarrierWave gem. Assuming you want images attached to a model Post.
in the model:
class Post < ActiveRecord::Base
has_many :photos, inverse_of: :post
end
you can then have a photo model:
class Photo < ActiveRecord::Base
belongs_to :post
mount_uploader :post_image, PostImageUploader
end
Then you can add this to app/uploaders/post_image_uploader.rb
class PostImageUploader < CarrierWave::Uploader::Base
# Create different versions of your uploaded files:
version :standard do
process resize_to_fit: [800, 800]
end
version :thumb do
process resize_to_fit: [100, 100]
end
end
since you are creating the images via an api, you'll have to convert the image to Base64 string and send as a param. on this example the base64 string is in param [:photo][:photo_data] before sending it to the server. in photos_controller.rb have this:
def create
#photo = Photo.new(photo_params)
#photo.post_image = decode_photo_data(params[:photo][:photo_data])
if #photo.save
render json: #photo, status: :created, location: #photo
else
render json: #photo.errors, status: :unprocessable_entity
end
end
#decode base64 data to an jpg image:
def decode_photo_data(photo_data)
data = StringIO.new(Base64.decode64(photo_data))
data.class.class_eval { attr_accessor :original_filename, :content_type }
data.original_filename = "upload.jpg"
data.content_type = "image/jpg"
# return decoded data
data
end
def photo_params
params.require(:photo).permit(:caption, :post_id)
end
With this, when you make a post request to your create photo api endpoint with a body like this
{"photo": {"caption": "an image", "post_id": 1, "photo_data":<your image base64 string>}}
it will create a photo with both a standard and a thumb version for the post with an id of 1.