ActiveStorage::FileNotFoundError in before_save

[franktisellano]

Steps to reproduce

Example Repo

Background

I'm using Active Storage with Disk storage. I want users to upload a json file attached to a model called Test_Model. The model has an attribute name that I'd like to populate with data from the JSON file.

When I call JSON.parse(self.jsonfile.download) to retrieve the name from the json file, I get an ActiveStorage::FileNotFoundError error.

Steps

1. Clone the Example Repo
2. bundle && rails db:migrate
3. Visit http://localhost:3000/test_models/new
4. Upload any file, leave Name blank

Expected behavior

I expect to be able to manipulate the as-yet-unsaved version of of this file before I save the record to the database.

Actual behavior

I get an ActiveStorage::FileNotFoundError error with the following exception cause: Errno::ENOENT: No such file or directory @ rb_sysopen - /Users/franktisellano/Desktop/activestorage-example/storage/i6/7e/i67ej7r9nx1yz838eor5v1hwpa3o.

System configuration

Rails version: 6.0.0

Ruby version: 2.5.0

Operating System: Mac 10.13.6 High Sierra

[georgeclaghorn]

This is the intended behavior (#33303). The file doesn’t get uploaded to storage until after the transaction commits. Download it after_commit instead:

class TestModel < ApplicationRecord
  has_one_attached :jsonfile
  after_commit :extract_name_from_json

  private
    def extract_name_from_json
      update! name: JSON.parse(jsonfile.download).fetch("name")
    end
end

[franktisellano]

@georgeclaghorn I'll do that, but is there no way to manipulate the file in-memory before saving it to disk permanently?

[franktisellano]

@georgeclaghorn That didn't work. I still receive the FileNotFound Error.

[ahmeij]

I'm facing the same problem. I have a custom validator that checks the contents of an uploaded excel file.

After a bit of searching I found the file can be accessed before_save or during validations with the following code:

record.attachment_changes['<attributename>'].attachable

This is a reference to the Tempfile that will be uploaded to storage during the save of the record.

[franktisellano]

I’ll do the same. Please post on this thread if you discover anything, Andre.

…

On Aug 21, 2019, at 8:06 AM, Andre Meij ***@***.***> wrote: I'm facing the same problem. I have a custom validator that checks the contents of an uploaded excel file. Is there no way to access the, not yet uploaded, file before save at all? Will dig a little deeper to try and figure that out. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or mute the thread.

[inopinatus]

The fact we used to be able to work with the unsaved file, and now cannot, is a thoroughly irksome regression.

[sofianeOuafir]

any solution?

[franktisellano]

any solution?

I ended up using File.read(self.attachment_changes['hlx_file'].attachable) to read the file using a before_create callback.

[mladenilic]

That didn't work. I still receive the FileNotFound Error.

Attachment is uploaded (stored on actual storage service) using after_commit callback.

Example that @georgeclaghorn provided will not work because after_ callbacks are executed in reverse order. This means that extract_name_from_json is executed before file is uploaded, hence the FileNotFound.

Here is the working example:

class TestModel < ApplicationRecord
  # Has to be called before has_one_attached
  after_commit :extract_name_from_json

  has_one_attached :jsonfile

  private
    def extract_name_from_json
      update! name: JSON.parse(jsonfile.download).fetch("name")
    end
end

@georgeclaghorn: What do you think about adding example of how to manipulate attachment with after_commit callback to the active storage guide? It might also be useful to add callback invoke order gotcha to the AR callback guide? I'd be happy to open PRs.

[ErikDeBruijn]

Changing the order fixed the problem, we can now finally upgrade to Rails 6 (see our issue here

[mihael]

Same here, fixed by changing order.

@mladenilic hvala za fix!

[XaviBatis]

Guys! the link 'example repo' is not working any more, could you please fix it so we can have all details ?

I tried to build a web app from scratch following your tips but I was getting errors probably bc i had to improvise some code, it would be a way more easier if you can reupload the 'example repo' to figure out how to go through the whole thing.

Thanks in advance