5 Steps Nested Attributes
Update multiple models from single form
Follow bold numbered sentences for instructions
Normal text for brief explanations.
If we have two models User and Address. Where a User (the parent) has_one address (the child) and we want to create/edit both using one form.
Our User model contains a name. Our Address model contains a city, state and a foreign key referencing its parent the user.
NB: Its important we add the reference to the parent model through the child and not the other way around!!!!!
1) Add accepts_nested_attributes_for: childmodel to the parent model
# app/models/user.rb
class User < ActiveRecord::Base
# ... code from above omitted
has_one :address
accepts_nested_attributes_for :address
end
# app/models/address.rb
class Address < ActiveRecord::Base
belongs_to :user
end
2) Inside our user form we add this
NOTE: f is the local variable that we passed for our main form do |f| Yours might have a different name (eg: form) so you will have to change it keep ff the same.
#app/views/_form.html.erb
<%= f.fields_for :address do |ff| %>
<div>
<%= ff.label :city %>
<%= ff.text_field :city %>
</div>
<div>
<%= ff.label :state %>
<%= ff.text_field :state %>
</div>
<% end %>3) Create a helper method file called form_helper.rb and add
Helper method is used so we can create a new address which we need in order to pass through the nested params
# app/helpers/form_helper.rb
module FormHelper
def setup_user(user)
user.address ||= Address.new
user
end
end
4) Update our main user form by removing the existing form_for do |f| and adding
We are calling our setup method so we can create our address model.
# app/views/users/_form.html.erb
<%= form_for(setup_user(user)) do |f| %>We need to white list the additional nested params coming through
5) Update our permitted params by adding ourmodel_attributes and the attributes it contains
#app/controllers/users_controllers.rb
def user_params
params.require(:user).permit(:name, address_attributes:[:city,:state])
end