Rails 5 error message: Child-Model Parent-Model must exist - nested-attributes

Question

I have two models, Parent is Property, child is Phone. When attempting to create a new Property record with nested Phone data, I receive an error message: Phones property must exist.
I've studied the Rails Guide and a number of other documents without determining the cause. Here is a public github link if you want to see all the code: https://github.com/allenroulston/testnest.git
class Property < ApplicationRecord
has_many :phones
accepts_nested_attributes_for :phones
end
class Phone < ApplicationRecord
belongs_to :property
end
# the form accepting the data
<%= form_for(property) do |f| %>
<% if property.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(property.errors.count, "error") %> prohibited this property from being saved:</h2>
<ul>
<% property.errors.full_messages.each do |message| %>
<li><%= message %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :name %>
<%= f.text_field :name %>
</div>
<div class="field">
<%= f.label :address %>
<%= f.text_field :address %>
</div>
<div class="field">
<%= f.label :city %>
<%= f.text_field :city %>
</div>
<div class="field">
<%= f.label "Telephone (example: 613 555 1234 )" %>
<%= f.fields_for :phones do |p| %>
Area Code <%= p.text_field :area %>
Exchange <%= p.text_field :exchange %>
Number <%= p.text_field :number %>
<% end %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
# relevant controller methods ##################
# GET /properties/new
def new
#property = Property.new
#property.phones.build
end
# POST /properties
# POST /properties.json
def create
#property = Property.new(property_params)
respond_to do |format|
if #property.save
format.html { redirect_to #property, notice: 'Property was successfully created.' }
format.json { render :show, status: :created, location: #property }
else
format.html { render :new }
format.json { render json: #property.errors, status: :unprocessable_entity }
end
end
end

Answer 1

As far as I know, this is because when you use nested_attributes_for when creating a new object, the parent object is not yet created, so when attempting to create a reference to the parent object, the validation fails. To fix this you should change to: has_many :phones, inverse_of: :property.

Answer 2

You need to add in the Property model as :-
accepts_nested_attributes_for :phones, reject_if: :all_blank, allow_destroy: true