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)
• 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' }
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

• 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

Internationalization (I18n)

Active Storage Validations use I18n for errors messages. For this add there 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"
      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."

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_type" containing the list of authorized content types.

It's 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:

gem 'active_storage_validations'

# Optional, to use :dimension validator
gem 'mini_magick'

And then execute:

$ bundle

Sample

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

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
• add aspect ratio validation

Tests & Contributing

To run tests in root folder of gem rake test.

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 Rails issue. And according to commits it will be 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

License

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