Grape POST request receiving JSON - ruby-on-rails-4

Question

I am having problem with grape.
I have tried to look into their docs and google around.
I could not find any solution or sample regarding this.
Let say I am sending this kind of format to the POST request of grape:
{
"preferences": {
"play": {
"weekdays": "5",
"weekend": "8"
},
"grow": {
"weekdays": "4",
"weekend": "8"
}
}
}
Questions:
How do I setup the Grape params to receive this post?
I have tried something like this:
params do
optional :preferences, type: Hash do
optional :play do
optional :weekdays
optional :weekend
end
optional :grow, type: Hash do
optional :weekdays
optional :weekend
end
end
end
I am using postman to do the POST on my chrome. My question is, How do I set the Hash kind of params ? There are 3 options on postman which are form-data, form-urlencoded, and raw. I have tried with form-data and raw (json) it does not work for the raw json, it gave me an error saying that
The requested content-type 'text/plain' is not supported
Any idea how do I fix these problems?
Thank you very much

Answer 1

Answering question 1: If all parameters are optional then you don't even need the params block. Get rid of it and, for example, use params[:preferences][:play][:weekdays] to access the weekdays attribute. Just use the same idea to access other values.
Answering question 2: On Postman, use RAW but don't forget to set the header Content-Type to application/json. I've written the code below to play around with this example.
require 'grape'
class API < Grape::API
version 'v1', :using => :header, :vendor => 'alienlabz', :format => :json
format :json
resource :preferences do
post do
puts params[:preferences][:play][:weekdays]
end
end
end
run API