A no-frills RESTful validation service for ActiveModel. Helps for the cases where you found that doing client-side validations is a bad idea. It is just an endpoint.

Mount it into your application (Rails or otherwise). Then, send it a request like so:

POST /?model=User

with a JSON body of:

{"name": "John Doe"}

POST implies you want to check if you are able to create an object. The app is going to instantiate a blank User model object, perform user#attributes = your_attributes and is going to call valid? on it. If it isn't valid, you are going to receive the errors back:

{
  "model": "User",
  "is_create": true,
  "valid": false,
  "errors": {
    "name": [
      "has already been taken"
    ]
  }
}

If it is valid, you the valid property in the JSON response will be true, and the errors property will be set to null. To perform a check for a modification, use PUT or PATCH (ActiveModel#attributes= works rather like a Hash#merge, not like a full-on replace assignment).

PUT /?model=User&id=123

will give the same response as the POST example, except that is_create will be set to true.

If you have I18n enabled, and you have enabled translation introspection, you will receive the translation keys instead of the translated error strings. To set up translation introspection, make sure that the I18n backend you use supports introspection:

class << I18n.backend
  include I18n::Backend::Metadata
end

This approach is relatively insecure as it allows for probing. Use something like Rack::Attack to limit the number of checks from a single IP/browser combination. Even then, use this sparingly. You may also restrict the models that can be validated from this endpoint by overriding model_accessible?(model_module)

• Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet.
• Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it.
• Fork the project.
• Start a feature/bugfix branch.
• Commit and push until you are happy with your contribution.
• Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.
• Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.

Copyright (c) 2016 WeTransfer. See LICENSE.txt for further details.