Devise signup with association

Question

I am working on a project app with patients and doctors. During sign up the patient with choose their doctor from a drop down list. I am not having any luck in associating the doctor and patient. I'm not sure if it has to to with devise or what but any help would be greatly appreciated. Below is a copy of the Patients Registrations controller and the signup.

class Patients::RegistrationsController < Devise::RegistrationsController
   before_action :configure_sign_up_params, only: [:create]
  # before_action :configure_account_update_params, only: [:update]

  # GET /resource/sign_up
  # def new
  #   super
  # end

  # POST /resource
  # def create
  #   super
  # end

  # GET /resource/edit
  # def edit
  #   super
  # end

  # PUT /resource
  # def update
  #   super
  # end

  # DELETE /resource
  # def destroy
  #   super
  # end

  # GET /resource/cancel
  # Forces the session data which is usually expired after sign
  # in to be expired now. This is useful if the user wants to
  # cancel oauth signing in/up in the middle of the process,
  # removing all OAuth session data.
  # def cancel
  #   super
  # end

  # protected

  # If you have extra params to permit, append them to the sanitizer.
   def configure_sign_up_params
     devise_parameter_sanitizer.permit(:sign_up, keys: [:first_name, :last_name, doctor_ids: []])
   end

  # The path used after sign up.
   def after_sign_up_path_for(resource)
     patient_path(resource)
   end

end

<h2>Sign up</h2>

<%= form_for(resource, as: resource_name, url: registration_path(resource_name), html: { data: { turbo: false} } ) do |f| %>
  <%= render "patients/shared/error_messages", resource: resource %>

  <div class="field">
    <%= f.label :first_name %><br />
    <%= f.text_field :first_name, autofocus: true, autocomplete: "email" %>
  </div>

  <div class="field">
    <%= f.label :last_name %><br />
    <%= f.text_field :last_name, autofocus: true, autocomplete: "email" %>
  </div>

  <div class="field">
    <%= f.label :email %><br />
    <%= f.email_field :email, autofocus: true, autocomplete: "email" %>
  </div>

  <div class="field">
    <%= f.label :password %>
    <% if @minimum_password_length %>
    <em>(<%= @minimum_password_length %> characters minimum)</em>
    <% end %><br />
    <%= f.password_field :password, autocomplete: "new-password" %>
  </div>

  <div class="field">
    <%= f.label :password_confirmation %><br />
    <%= f.password_field :password_confirmation, autocomplete: "new-password" %>
  </div>

  <%= collection_select(resource, :doctor_id, Doctor.all, :id, :fullname, :prompt => 'Select your Doctor') %>

  <div class="actions">
    <%= f.submit "Sign up" %>
  </div>
<% end %>

<%= render "patients/shared/links" %>