#{column}_url equals to nil after saving object

[virolea]

I came across an issue trying to save an image. I'm submitting a form with an image, and update an existing record with it. I'm doing through an xhr request from the client, and I want the request to send the image url back.

def update
  record = Record.find(params[:id])
  record.update(photo: params[:photo])
  render json: record.photo.url, status: :ok
end

Carriewave's doc specifies:

u = User.new
u.avatar = params[:file]

u.save!
u.avatar.url # => '/url/to/file.png'

Will help me get my file url. However my action returns nil but it works if I instantiate a new version of the record:

I did some testing in the console to show my point:

So the only way I can get the url of the image without having to fetch the record again, after having a look at the uploader object is through:

c.photo.metadata['url']
# => returns the url

Config:
Rails 5.1.4
Carrierwave 1.2.1

[gjamerson]

I'm having the same issue.
Rails 4.2.10
Carrierwave 1.2.1

[rbclark]

I believe I am experiencing this exact same issue and it seems to be exhibiting itself inside of my test suite. I hand off to a background worker where the ProductTest is updated and then have been running the following commands to compare the response.

pt.reload
=> nil
pt == ProductTest.last
=> true
pt.patient_archive.file
=> nil
ProductTest.last.patient_archive.file
=> #<CarrierWave::SanitizedFile:0x00007fd07bc67a20
 @content_type=nil,
 @file="/path/to/rails/public/data/upload/product_test/5ab4243dc60ac1cce7e23546/product_test-5ab4243dc60ac1cce7e23546.zip20180322-52455-1dmh03x",
 @original_filename=nil>
pt.patient_archive.file
=> nil

It seems that the reload is not properly refreshing the file, even though it did previously on Carrierwave (0.11.2) and carrierwave-mongoid (0.9.0)

I was originally going to post this on carrierwave-mongoid however it seems this issue already closely resembles my issues so I'm unsure if the issue is here or carrierwave-mongoid.

This is now happening for me one
rails (4.2.10)
carrierwave (1.2.2)
carrierwave-mongoid (1.0.0)

[rbclark]

Just wanted to bump this and see if there is any other info I can provide to help get this issue fixed? It is blocking a few other tasks I have so if there is anything I can do or provide please let me know.

[danderozier]

I seem to be having the same issue in Rails 5.2 and Carrierwave 1.2.2. The object returned after saving returns nil for the url, but instantiating a new object for the same record works as expected.

[virolea]

I might have a look at the code and submit a PR if I find the time.
Now that rails 5.2 and active storage are out, I might move from carrierwave in the near future

[p8]

I think the problem is in the following code:

carrierwave/lib/carrierwave/mounter.rb

Line 35 in 97c028c

uploader.retrieve_from_store!(identifier) if identifier.present?

  def uploaders
      @uploaders ||= read_identifiers.map do |identifier|
        uploader = blank_uploader
        uploader.retrieve_from_store!(identifier) if identifier.present?
        uploader
      end
  end

When a model is initialized before the identifier is set retrieve_from_store! will not be called because @uploaders is already set.

This did work differently in 0.11 (with single uploaders). retrieve_from_store! can be called later on when the identifier is set.

  def uploader
    @uploader ||= record.class.uploaders[column].new(record, column)
    @uploader.retrieve_from_store!(identifier) if @uploader.blank? && identifier.present?
    @uploader
  end

So a fix will probably be to move the call to retrieve_from_store! outside the loop.

[p8]

Unsetting the @uploaders instance variable on the mounter seems to fix it.

    attachment.url # => nil    
    _mounter(:attachment).instance_variable_set(:@uploaders, nil)
    attachment.url # => the correct url

[mshibuya]

I don't understand what makes the attribute and @uploaders out of sync.
Can anyone reproduce this using a vanilla Rails app?

[mshibuya]

Stale, please reopen on update.