typeerror - ActionController “No explicit conversion of Symbol into Integer” for new record in Rails 4.2.1 -

i'm trying create @booking , @booking.build_passenger in form_for nested attributes in rails 4.2.1

the error get:

as see in console @ bottom of image:
1. params.require(:booking) returns hash-like params @booking
2. params.class returns actioncontroller::parameters

as params seems behave correctly, imo problem hides somewhere in form:

<%= form_for @booking |f| %>        <%= f.hidden_field :flight_id, value: params[:flight_id] %>        <%= render 'flights/flight_info' %>        <div class="field">          <b><%= f.label :num_tickets, "tickets" %></b>            <%= f.select(:num_tickets, @num_tickets) %>      </div><br>          <h4>passenger info:</h4>      <%= f.fields_for @booking.build_passenger |pass| %>          <div class="field">              <%= pass.label :name %>              <%= pass.text_field :name %>          </div>          <div class="field">              <%= pass.label :email %>              <%= pass.email_field :email %>          </div>      <% end %>      <%= f.submit 'book flight!' %>  <% end %>

booking model:

class booking < activerecord::base   belongs_to :flight   belongs_to :passenger   accepts_nested_attributes_for :passenger end 

---

question: , how have edit code app start creating @booking instances + @booking.build_passenger()

your booking_params needs like:

def booking_params   params.require(:booking).permit(:flight_id, :num_tickets, passenger_attributes: [:id, :name, :email]) end