I have a one-to-many association in Ruby on Rails:

class Booking < ActiveRecord::Base
  has_many :rides
  accepts_nested_attributes_for :rides, allow_destroy: true
end

### and ###

class Ride < ActiveRecord::Base
  belongs_to :bookings
end

The booking and ride views and controllers were scaffolded.

I wanted an "Add rides" button in my bookings form:

= simple_form_for(@booking) do |f|
  = f.error_notification
  = f.error_notification message: f.object.errors[:base].to_sentence if f.object.errors[:base].present?

  .form-inputs
    .container
      .row
        .col-6
          = f.input :first_name
          = f.input :phone_number
        .col-6
          = f.input :last_name
          = f.input :email
        .col-12
          = f.input :company


### here is the simple fields that does not work:

  = f.simple_fields_for :rides do |ride|
    = render 'rides/form', :f => ride
    = link_to_add_association 'add ride', f, :rides

However, nothing gets displayed and I don't know why.

Things I've tried:

1. Add rides_build I tried to add this to the booking controller

  def new
    @booking = Booking.new
    @booking.build_rides
  end

But it only gave me an error "undefined method `build_rides' for #Booking:0x000000010575c578"

2. Add rides.build

  def new
    @booking = Booking.new
    @booking.rides.build
  end

This also gave me an error message: "undefined method `model_name' for nil:NilClass"

3. Add only ride

  def new
    @booking = Booking.new
    @booking.build
  end

This just didn't do anything. No error, but the problem wasn't solved.

4. Change ApplicationRecord to ActiveRecord::Base This solved it for someone else, but not for me.

Might also want to add that absolutely nothing gets rendered that's inside the simple_fields_for, not even a simple h1.

CodePudding user response：

Option 2 is the correct way and should work, but you have an error in your Ride model, it should say

 belongs_to :booking 

Note: the simple_fields_for iterates over nested children, as long as there are none, nothing will get rendered.