Active Storage Validations

If you are using active_storage gem and you want to add simple validations for it, like presence or content_type you need to write a custom valiation method.

This gems doing it for you. Just use attached: true or content_type: 'image/png' validation.

What it can do

• validates if file(s) attached
• validates content type
• validates size of files
• validates dimension of images/videos
• validates number of uploaded files (min/max required)
• validates aspect ratio (if square, portrait, landscape, is_16_9, ...)
• custom error messages

Usage

For example you have a model like this and you want to add validation.

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' }
  validates :image, attached: true,
                    content_type: ['image/png', 'image/jpg'],
                    aspect_ratio: :landscape
end

or

class Project < ApplicationRecord
  has_one_attached :preview
  has_one_attached :attachment
  has_many_attached :documents

  validates :title, presence: true

  validates :preview, attached: true, size: { less_than: 100.megabytes , message: 'is not given between size' }
  validates :attachment, attached: true, content_type: { in: 'application/pdf', message: 'is not a PDF' }
  validates :documents, limit: { min: 1, max: 3 }
end

More examples

• Content type validation using symbols. In order to infer the correct mime type from the symbol, the types must be registered with Mime::Type.

class User < ApplicationRecord
  has_one_attached :avatar
  has_many_attached :photos

  validates :avatar, attached: true, content_type: :png # Mime[:png].to_s => 'image/png'
  # or
  validates :photos, attached: true, content_type: [:png, :jpg, :jpeg]
  # or
  validates :avatar, content_type: /\Aimage\/.*\z/
end

• Dimension validation with width, height and in.

class User < ApplicationRecord
  has_one_attached :avatar
  has_many_attached :photos

  validates :avatar, dimension: { width: { in: 80..100 }, message: 'is not given between dimension' }
  validates :photos, dimension: { height: { in: 600..1800 } }
end

• Dimension validation with min and max range for width and height:

class User < ApplicationRecord
  has_one_attached :avatar
  has_many_attached :photos

  validates :avatar, dimension: { min: 200..100 }
  # Equivalent to:
  # validates :avatar, dimension: { width: { min: 200 }, height: { min: 100  } }
  validates :photos, dimension: { min: 200..100, max: 400..200 }
  # Equivalent to:
  # validates :avatar, dimension: { width: { min: 200, max: 400 }, height: { min: 100, max: 200  } }
end

• Aspect ratio validation:

class User < ApplicationRecord
  has_one_attached :avatar
  has_one_attached :photo
  has_many_attached :photos

  validates :avatar, aspect_ratio: :square
  validates :photo, aspect_ratio: :landscape

  # you can also pass dynamic aspect ratio, like :is_4_3, :is_16_9, etc
  validates :photos, aspect_ratio: :is_4_3
end

Internationalization (I18n)

Active Storage Validations uses I18n for error messages. For this, add these keys in your translation file:

en:
  errors:
    messages:
      content_type_invalid: "has an invalid content type"
      file_size_out_of_range: "size %{file_size} is not between required range"
      limit_out_of_range: "total number is out of range"
      image_metadata_missing: "is not a valid image"
      dimension_min_inclusion: "must be greater than or equal to %{width} x %{height} pixel."
      dimension_max_inclusion: "must be less than or equal to %{width} x %{height} pixel."
      dimension_width_inclusion: "width is not included between %{min} and %{max} pixel."
      dimension_height_inclusion: "height is not included between %{min} and %{max} pixel."
      dimension_width_greater_than_or_equal_to: "width must be greater than or equal to %{length} pixel."
      dimension_height_greater_than_or_equal_to: "height must be greater than or equal to %{length} pixel."
      dimension_width_less_than_or_equal_to: "width must be less than or equal to %{length} pixel."
      dimension_height_less_than_or_equal_to: "height must be less than or equal to %{length} pixel."
      dimension_width_equal_to: "width must be equal to %{length} pixel."
      dimension_height_equal_to: "height must be equal to %{length} pixel."
      aspect_ratio_not_square: "must be a square image"
      aspect_ratio_not_portrait: "must be a portrait image"
      aspect_ratio_not_landscape: "must be a landscape image"
      aspect_ratio_is_not: "must have an aspect ratio of %{aspect_ratio}"
      aspect_ratio_unknown: "has an unknown aspect ratio"

In some cases, Active Storage Validations provides variables to help you customize messages:

The "content_type_invalid" key has two variables that you can use, a variable named "content_type" containing the content type of the send file and a variable named "authorized_types" containing the list of authorized content types.

The variables are not used by default to leave the choice to the user.

For example :

content_type_invalid: "has an invalid content type : %{content_type}"

Also the "limit_out_of_range" key supports two variables the "min" and "max".

For example :

limit_out_of_range: "total number is out of range. range: [%{min}, %{max}]"

Installation

Add this line to your application's Gemfile:

# Rails 5.2 and Rails 6
gem 'active_storage_validations'

# Optional, to use :dimension validator or :aspect_ratio validator
gem 'mini_magick', '>= 4.9.5'

And then execute:

$ bundle

Sample

Very simple example of validation with file attached, content type check and custom error message.

Test matchers

Provides RSpec-compatible and Minitest-compatible matchers for testing the validators.

RSpec

In spec_helper.rb, you'll need to require the matchers:

require 'active_storage_validations/matchers'

And include the module:

RSpec.configure do |config|
  config.include ActiveStorageValidations::Matchers
end

Example (Note that the options are chainable):

describe User do
  it { is_expected.to validate_attached_of(:avatar) }

  it { is_expected.to validate_content_type_of(:avatar).allowing('image/png', 'image/gif') }
  it { is_expected.to validate_content_type_of(:avatar).rejecting('text/plain', 'text/xml') }

  it { is_expected.to validate_dimensions_of(:avatar).width(250) }
  it { is_expected.to validate_dimensions_of(:avatar).height(200) }
  it { is_expected.to validate_dimensions_of(:avatar).width_min(200) }
  it { is_expected.to validate_dimensions_of(:avatar).width_max(500) }
  it { is_expected.to validate_dimensions_of(:avatar).height_min(100) }
  it { is_expected.to validate_dimensions_of(:avatar).height_max(300) }
  it { is_expected.to validate_dimensions_of(:avatar).width_between(200..500) }
  it { is_expected.to validate_dimensions_of(:avatar).height_between(100..300) }

  it { is_expected.to validate_size_of(:avatar).less_than(50.kilobytes) }
  it { is_expected.to validate_size_of(:avatar).less_than_or_equal_to(50.kilobytes) }
  it { is_expected.to validate_size_of(:avatar).greater_than(1.kilobyte) }
  it { is_expected.to validate_size_of(:avatar).greater_than_or_equal_to(1.kilobyte) }
  it { is_expected.to validate_size_of(:avatar).between(100..500.kilobytes) }
end

Minitest

To use the following syntax, make sure you have the shoulda-context gem up and running. To make use of the matchers you need to require the matchers:

require 'active_storage_validations/matchers'

And extend the module:

class ActiveSupport::TestCase
  extend ActiveStorageValidations::Matchers
end

Example (Note that the options are chainable):

class UserTest < ActiveSupport::TestCase
  should validate_attached_of(:avatar)

  should validate_content_type_of(:avatar).allowing('image/png', 'image/gif')
  should validate_content_type_of(:avatar).rejecting('text/plain', 'text/xml')

  should validate_dimensions_of(:avatar).width(250)
  should validate_dimensions_of(:avatar).height(200)
  should validate_dimensions_of(:avatar).width_min(200)
  should validate_dimensions_of(:avatar).width_max(500)
  should validate_dimensions_of(:avatar).height_min(100)
  should validate_dimensions_of(:avatar).height_max(300)
  should validate_dimensions_of(:avatar).width_between(200..500)
  should validate_dimensions_of(:avatar).height_between(100..300)

  should validate_size_of(:avatar).less_than(50.kilobytes)
  should validate_size_of(:avatar).less_than_or_equal_to(50.kilobytes)
  should validate_size_of(:avatar).greater_than(1.kilobyte)
  should validate_size_of(:avatar).greater_than_or_equal_to(1.kilobyte)
  should validate_size_of(:avatar).between(100..500.kilobytes)
end

Todo

• verify with remote storages (s3, etc)
• verify how it works with direct upload
• better error message when content_size is invalid
• add more translations

Tests & Contributing

To run tests in root folder of gem:

• BUNDLE_GEMFILE=gemfiles/rails_5_2.gemfile bundle exec rake test to run for Rails 5.2
• BUNDLE_GEMFILE=gemfiles/rails_6_0.gemfile bundle exec rake test to run for Rails 6.0

To play with app cd test/dummy and rails s -b 0.0.0.0 (before rails db:migrate).

Known issues

• There is an issue in Rails which it possible to get if you have added a validation and generating for example an image preview of attachments. It can be fixed with this:

  <% if @user.avatar.attached? && @user.avatar.attachment.blob.present? && @user.avatar.attachment.blob.persisted? %>
    <%= image_tag @user.avatar %>
  <% end %>

This is a Rails issue, and is fixed in Rails 6.

Contributing

You are welcome to contribute.

Contributors (BIG THANK YOU)

• https://github.com/schweigert
• https://github.com/tleneveu
• https://github.com/reckerswartz
• https://github.com/Uysim
• https://github.com/D-system
• https://github.com/ivanelrey
• https://github.com/phlegx
• https://github.com/rr-dev
• https://github.com/dsmalko
• https://github.com/danderozier
• https://github.com/cseelus
• https://github.com/vkinelev
• https://github.com/reed
• https://github.com/connorshea
• https://github.com/Atul9
• https://github.com/victorbueno
• https://github.com/UICJohn
• https://github.com/giovannibonetti
• https://github.com/dlepage
• https://github.com/StefSchenkelaars
• https://github.com/willnet
• https://github.com/mohanklein
• https://github.com/High5Apps

License

The gem is available as open source under the terms of the MIT License.