Rails does not nest nested posted JSON Object in parameters - ruby-on-rails

Question

I'm posting the following JSON to the rails create method in my 'user_controller' controller class.
{"user_detail_attributes":
{
"login":"dan123456",
"password":"password",
"password_confirmation":"password"
},
"surname":"REST_TEST",
"firstname":"REST_TEST",
"phone":"0456782",
"grad_year":2010,
"jobs":false,
"email":"REST_TEST#EMAIL.co.uk"
}
My user_params are as follows:
params.require(:user).permit(
:surname, :firstname, :phone, :grad_year, :jobs, :email,
user_detail_attributes: [:id, :password, :password_confirmation, :login])
Rails should then map this json to the user.
So the params variable should contain a user, inside that user should be the attributes including the user_detail_attributes.
However the user_detail attributes are appearing outside the user params variable as a completely seperate params variable, on the same level as the users params.
So, what should be happening:
user
+surname
+firstname
.
.
.
+user_detail_attributes
+login
+password
+password_confirmation
What's actually happening:
user_detail_attributes
+login
+password
+password_confirmation
user
+surname
+firstname
.
.
.
This then leads to the user being mapped to the user table in my database but no user_details being mapped to that table.
Does anyone know why this is happening and whether I can fix it? And if it is something that I need to do with the JSON format or something in the rails application.
Thanks,
Dan
EDIT: Fixed

Answer 1

According to the Strong Parameters Documentation
You should be doing something like this:
parameters.require(:user).permit(:surname, :firstname, :phone, :grad_year, :jobs, :email, {user_detail_attributes: [:login, :password, :password_confirmation] })
Note the {} before and after the user_detail_attributes
My test in console
hash = {user: {user_detail_attributes: { login: "dan123456", password: "password", password_confirmation: "password"}, surname:"REST_TEST", firstname:"REST_TEST", phone:"0456782", grad_year:2010, jobs:false, email:"REST_TEST#EMAIL.co.uk"} }
params = ActionController::Parameters.new(params)
parameters.require(:user).permit(:surname, :firstname, :phone, :grad_year, :jobs, :email, {user_detail_attributes: [:login, :password, :password_confirmation] })
Outuput:
{"surname"=>"REST_TEST", "firstname"=>"REST_TEST", "phone"=>"0456782", "grad_year"=>2010, "jobs"=>false, "email"=>"REST_TEST#EMAIL.co.uk", "user_detail_attributes"=>{"login"=>"dan123456", "password"=>"password", "password_confirmation"=>"password"}}

Answer 2

I've worked out the problem.
The JSON should be formatted as follows:
{"user":
{"user_detail_attributes":
{
"login":"dan123456",
"password":"password",
"password_confirmation":"password"
},
"surname":"REST_TEST",
"firstname":"REST_TEST",
"phone":"0456782",
"grad_year":2010,
"jobs":false,
"email":"REST_TEST#EMAIL.co.uk"
}
}
I was missing the user attribute at the start as this was how my c# JSON encoder was formatting the JSON from my user and user_detail_attribute classes.
I had a play around by creating the JSON manually and this turned out to be the fix.
Thanks for everyone's help :)