RailsAdmin Carrierwave Multiple Upload undefined method `filename' for nil:NilClass - carrierwave

Question

Following Carrierwave and RailsAdmin instructions I can preform multiple uploads in RailsAdmin with Carrierwave, using aws S3. When trying to delete one of the images I get:
undefined method 'filename' for nil:NilClass
The assets field is a json field, assets:json
This is in my model:
attr_accessor :delete_assets
after_validation do
uploaders = assets.delete_if do |uploader|
if Array(delete_assets).include?(uploader.file.filename)
uploader.remove!
true
end
end
write_attribute(:assets, uploaders.map { |uploader| uploader.file.filename })
end
I tried uploader.file.identifier but read that when using fog aws S3 the uploader.file.filename should be used.
My resources so far:
RailsAdmin
https://github.com/carrierwaveuploader/carrierwave/blob/master/README.md#multiple-file-uploads
Carrierwave:
https://github.com/sferik/rails_admin/wiki/CarrierWave
Stackoverflow:
Rails Admin - undefined method `' for using Carrierwave multiple upload
How do I delete a previously uploaded image from this json array? Any help is much appreciated!

Answer 1

The problem here is certain uploaders don't have a file attached. So your error is because you're calling filename on nil - aka uploader.file returns nil.
You'll likely want to handle this occurrence, something like the following:
attr_accessor :delete_assets
after_validation do
uploaders = assets.delete_if do |uploader|
next unless uploader.file # <-- skip deleting assets without a file
if Array(delete_assets).include?(uploader.file.filename)
uploader.remove!
true
end
end
write_attribute(:assets, uploaders.map { |uploader| uploader.file.filename })
end
Or if you'd rather remove all assets missing a file:
attr_accessor :delete_assets
after_validation do
uploaders = assets.delete_if do |uploader|
next true unless uploader.file # <-- note 'true' added here
if Array(delete_assets).include?(uploader.file.filename)
uploader.remove!
true
end
end
write_attribute(:assets, uploaders.map { |uploader| uploader.file.filename })
end
Otherwise, the route you'll need to go down will be validating the presence of a file on an uploader, which is likely a separate question.
Hope this helps - let me know how you get on or if you have any questions here :)