Ruby on Rails

class User < ActiveRecord::Base

  # Assume devise user here

  has_many :user_surveys

  has_many :surveys, through: :user_surveys

  has_many :responses

end

class Survey < ActiveRecord::Base

  has_many :questions

  has_many :user_surveys

  has_many :users, through: :user_surveys

  accepts_nested_attributes_for :questions

 # name: string

end

class Question < ActiveRecord::Base

  belongs_to :survey

  has_many :responses

  accepts_nested_attributes_for :responses

 # response_text: string

end

Class Response < ActiveRecord::Base

  belongs_to :question

  belongs_to :user

  # response_text: string

end

The idea being, an admin can create a survey with questions, and then assign that survey to users through the join model UserSurvey.

Now imagine a basic form that we give the user for their survey that looks like this:

My main question revolves around the following line (under fields_for responses):

I see it suggested other places (eg: here on stackoverflow, or this tutorial here ) to put a hidden user_id field, but this feels incredibly wrong to me -- if a user is malicious, they could edit the form and modify the hidden user_id field to modify another participants answer.

Now, the one solution I did think was that on the controller side I could mess with the params, IE assume the submitted parameters look as follows

"survey"=>{"questions_attributes"=>{"0"=>{"responses_attributes"=>{"0"=>{"response_text"=>"one"}}, "id"=>"7"}, "1"=>{"responses_attributes"=>{"0"=>{"response_text"=>"two"}}, "id"=>"8"}}}

I could do something like:

This way, I not only check to make sure the survey is attached to the user, but also make sure the questions they are submitting are attached to that specific survey, and the responses are not only tied to the correct question, but also back to the correct user. This feels messy though, and I feel I'm majorly overthinking this.

Can anyone give me a sanity check as to what  I'm doing wrong?