Prompt error status RAILS - API - ruby-on-rails

Question

I have basically this:
class Api::NameController < ApplicationController
skip_before_filter :verify_authenticity_token
def index
end
def create
begin
cou = params[:data].count
rescue
render status: 422, json: {
message: "Error Loading data- Check your data",
}.to_json
end
input = params[:data]
# Operations with the input data
render status: 200, json: {
message: "Succesful data calculation",
data_output: input
}.to_json
end
end
The data is: {"data":[1,34,5]}
I would like to render the status error 422, when the data has a bad sintax (example: {"dat":[1,34,5]} or {"data":1,34,5]} etc)
With the example above doe not work. When sending via cURL {"data":1,34,5]} I got:
Started POST "/api/energy" for 127.0.0.1 at 2015-05-29 08:35:50 +0200
Error occurred while parsing request parameters.
Contents:
{"data":1,5,67]}
ActionDispatch::ParamsParser::ParseError (795: unexpected token at '{"data":1,5,67]}'):
When sending {"dat":[1,34,5]} I got
Processing by Api::EnergyController#create as JSON
Parameters: {"dat"=>[1, 5, 67], "energy"=>{"dat"=>[1, 5, 67]}}
Completed 500 Internal Server Error in 1ms (Views: 0.2ms | ActiveRecord: 0.0ms)
AbstractController::DoubleRenderError (Render and/or redirect were called multiple times in this action. Please note that you may only call render OR redirect, and at most once per action. Also note that neither redirect nor render terminate execution of the action, so if you want to exit an action after redirecting, you need to do something like "redirect_to(...) and return".):
Could anyone help me putting this error status in the correct form?