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Upload files encoded as base64 strings directly to carrierwave

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Upload files encoded as base64 to carrierwave.

This small gem can be useful for API's that interact with mobile devices.

This gem requires Ruby 2.0 or higher.


Add the gem to your Gemfile:

gem 'carrierwave-base64'

Also add this if you need mongoid support:

gem "carrierwave-mongoid"


Mount the uploader to your model:

mount_base64_uploader :image, ImageUploader

Now you can also upload files by passing an encoded base64 string to the attribute. This also works for normal file uploads from file fields inside an HTML form, so you can safely replace

to support both file input and base64 encoded input

Upload file extension

The file extension for the uploaded base64 string is identified automatically using the mime-types gem and

from the uploaded string.

If the required MIME type is not registered, you can add it, using MIME::Types#add:

MIME::Types.add('application/icml').tap do |type|
    type.add_extensions 'icml'

Setting the file name

You can set the

option to a lambda, that will return a filename without an extension, using the model instance:
mount_base64_uploader :image, ImageUploader, file_name: -> (u) { u.username }

[DEPRECATED: Settings this option to a string is deprecated, if you still want to set the filename to a fixed string, wrap it in a Proc] To set the file name for the uploaded files, use the

option (without extention):
# Deprecated way:
mount_base64_uploader :image, ImageUploader, file_name: 'userpic'

New way

mount_base64_uploader :image, ImageUploader, file_name: -> { 'userpic' }

Data format

File extention for the uploaded file is identified automatically based on the file contents. If it can't be identified automaticaly, it falls back to the content-type, specified in the data string.

data:image/jpeg;base64,(base64 encoded data)


  1. Fork it ([my-github-username]/carrierwave-base64/fork )
  2. Create your feature branch (
    git checkout -b my-new-feature
  3. Commit your changes (
    git commit -am 'Add some feature'
  4. Push to the branch (
    git push origin my-new-feature
  5. Create a new Pull Request

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