ActiveStorage File Attachment Validation

Question

Is there a way to validate attachments with ActiveStorage? For example, if I want to validate the content type or the file size?

Something like Paperclip\'s approach wou

Answer 1

Well, it ain't pretty, but this may be necessary until they bake in some validation:

  validate :logo_validation

  def logo_validation
    if logo.attached?
      if logo.blob.byte_size > 1000000
        logo.purge
        errors[:base] << 'Too big'
      elsif !logo.blob.content_type.starts_with?('image/')
        logo.purge
        errors[:base] << 'Wrong format'
      end
    end
  end

Answer 2

You can use awesome https://github.com/musaffa/file_validators gem

class Profile < ActiveRecord::Base
  has_one_attached :avatar
  validates :avatar, file_size: { less_than_or_equal_to: 100.kilobytes },
    file_content_type: { allow: ['image/jpeg', 'image/png'] }
end

I'm using it with form object so I'm not 100% sure it is working directly with AR but it should...

Answer 3

Copy contents of the ActiveStorage's DirectUploadsController in the app/controllers/active_storage/direct_uploads_controller.rb file and modify the create method. You can add authentication to this controller, add general validations on the file size or mime type, because create method of this controller creates the url for the file to be uploaded. So you can prevent any file upload by controlling size and mime type in this controller.

A simple validation could be:

# ...
def create
  raise SomeError if blob_args[:byte_size] > 10240 # 10 megabytes
  blob = ActiveStorage::Blob.create_before_direct_upload!(blob_args)
  render json: direct_upload_json(blob)
end
# ...

Answer 4

ActiveStorage doesn't support validations right now. According to https://github.com/rails/rails/issues/31656.

---

Update:

Rails 6 will support ActiveStorage validations.

https://github.com/rails/rails/commit/e8682c5bf051517b0b265e446aa1a7eccfd47bf7

Uploaded files assigned to a record are persisted to storage when the record
is saved instead of immediately.
In Rails 5.2, the following causes an uploaded file in `params[:avatar]` to
be stored:
```ruby
@user.avatar = params[:avatar]
```
In Rails 6, the uploaded file is stored when `@user` is successfully saved.

Answer 5

I found a way to validate and delete attachments with callback before_save. This is a useful approach because if you validate file during the transaction (and you want to purge it), after adding error and it will rollback deleting the attachment.

before_save :check_logo_file, on: %i[create update]

def check_favicon_content_type
    PartnerValidators::CustomPartnerFaviconValidator.new.validate(self)
end

module PartnerValidators
    class CustomPartnerFaviconValidator < ActiveModel::Validator
        ALLOWED_MIME_TYPES = %w(image/vnd.microsoft.icon image/x-icon image/png).freeze
        private_constant :ALLOWED_MIME_TYPES

        def validate(partner)
            if partner.favicon.attached? && invalid_content_type?(partner)
                partner.errors.add(:favicon, I18n.t("active_admin.errors.favicon"))
                partner.favicon.purge
            end
        end

        private

        def invalid_content_type?(partner)
            !partner.favicon.blob.content_type.in?(ALLOWED_MIME_TYPES)
        end
    end
end

Answer 6

Came across this gem: https://github.com/igorkasyanchuk/active_storage_validations

class User < ApplicationRecord
  has_one_attached :avatar
  has_many_attached :photos

  validates :name, presence: true

  validates :avatar, attached: true, content_type: 'image/png',
                                     dimension: { width: 200, height: 200 }
  validates :photos, attached: true, content_type: ['image/png', 'image/jpg', 'image/jpeg'],
                                     dimension: { width: { min: 800, max: 2400 },
                                                  height: { min: 600, max: 1800 }, message: 'is not given between dimension' }
end