ActiveStorage Validator

A Rails gem that makes it easy to add validations such as content_type and file size to ActiveStorage attachments.

• Supports both has_one_attached and has_many_attached of ActiveStorage
• Flexible validations for content type and file size

Add this line to your application's Gemfile:

gem 'activestorage-validator'

Then execute:

$ bundle install

$ gem install activestorage-validator

You can add validations to models with ActiveStorage attachments using the blob validator.

class User < ApplicationRecord
  has_one_attached :avatar
  has_many_attached :photos

  # Allow only web image files
  validates :avatar, presence: true, blob: { content_type: :web_image }

  # Allow only JPEG/PNG, up to 5MB per file
  validates :photos, presence: true, blob: { content_type: ["image/png", "image/jpg", "image/jpeg"], size_range: 1..(5.megabytes) }

  # You can also use a regular expression for content_type
  # validates :photos, blob: { content_type: %r{^image/}, size_range: 1..(5.megabytes) }
end

Note: For has_many_attached, the size validation is applied to each file individually.

• Symbol
  • :web_image ... PNG, JPEG, GIF, WebP (special handling)
  • :image, :audio, :video, :text ... Calls blob.image?, blob.audio?, etc. (ActiveStorage built-in predicate)
• Array
  • ["image/png", "image/jpg", "image/jpeg"] ... Only allow these MIME types
• Regexp
  • %r{^image/} ... Allow any image type (MIME type starts with image/)
• String
  • "application/pdf" ... Only allow PDF files

Validation error messages are I18n compatible. The following interpolation keys are available in your translation files, according to the validator's implementation:

The following error types are used:

• content_type (invalid content type)
• min_size_error (file is too small)
• max_size_error (file is too large)

Example (config/locales/en.yml):

en:
  errors:
    messages:
      content_type: "%{filename} has an invalid content type"
      min_size_error: "%{filename} is too small (minimum is %{min_size})"
      max_size_error: "%{filename} is too large (maximum is %{max_size})"

• Some features may not work depending on your ActiveStorage or Rails version.
• Validation error messages are I18n compatible and support interpolation keys as described above.

Bug reports and pull requests are welcome on GitHub via issues or pull requests.

This project adheres to the Contributor Covenant code of conduct.

This gem is released under the MIT License. See LICENSE.txt for details.