An example of a Request middleware to send the body as XML

faraday-request-xml.rb

module FaradayMiddleware
  class XmlRequest < Faraday::Middleware
    dependency do
      require 'active_support/all'
    end

    def call(env)
      if env[:method] == :post
        body = env[:body]
        first_key = body.keys.first

        env[:body] = body[first_key].to_xml(skip_instruct: true, root: first_key)
      end

      @app.call(env)
    end
  end
end

if Faraday.respond_to? :register_middleware
  Faraday.register_middleware :request, xml: -> { FaradayMiddlware::XmlRequest }
end

# usage
# Faraday.new(...) do |conn|
#   conn.request(:xml)
# end