rails - “WARNING: Can't verify CSRF token authenticity” for json devise requests

Question

How can I retrieve the CSRF token to pass with a JSON request?

I know that for security reasons Rails is checking the CSRF token on all the request types (including

Answer 1

Also for development/test mode.

protect_from_forgery with: :exception unless %w(development test).include? Rails.env

This warning shows because you are using :null_session, in Rails 4.1 it works by default if no with: options specified.

protect_from_forgery