rails has_one through form - ruby-on-rails

Question

administrator.rb:
class Administrator < ActiveRecord::Base
has_one :administrator_role, dependent: :destroy
has_one :role, through: :administrator_role
end
role.rb:
class Role < ActiveRecord::Base
has_many :administrator_roles
has_many :administrators, through: :administrator_roles
end
administrator_role.rb:
class AdministratorRole < ActiveRecord::Base
belongs_to :administrator
belongs_to :role
end
in view for "new" action administrator_controller:
<%= form_for #administrator do |f| %>
<%= render 'shared/errors', object: #administrator %>
<div class="form-group">
<%= f.label :role_id, "Роль:" %>
<%= f.collection_select(:role_id, #roles, :id, :name) %>
</div>
...
<%= f.submit 'Save', class: 'btn btn-primary btn-lg' %>
<% end %>
administrator_controller.rb:
class AdministratorsController < ApplicationController
def new
#administrator = Administrator.new
#roles = Role.all
end
def create
#administrator = Administrator.new(administrators_params)
if #administrator.save
flash[:success] = "Account registered!"
redirect_to root_path
else
render :new
end
end
...
private
def administrators_params
params.require(:administrator).permit(:login, :password, :password_confirmation, :role_id)
end
end
when you open the page get the error:
undefined method `role_id' for #<Administrator:0x007f6ffc859b48>
Did you mean? role
How to fix it? if I put in place role_id a role, when you create administrator will get the error:
ActiveRecord::AssociationTypeMismatch (Role(#69964494936160) expected, got String(#12025960)):

Answer 1

You have to rewrite the form as below:
<%= form_for #administrator do |f| %>
<%= render 'shared/errors', object: #administrator %>
<div class="form-group">
<%= f.fields_for :role do |role_form| %
<%= role_form.label :role_id, "Роль:" %>
<%= role_form.select(:id, #roles.map { |role| [role.name, role.id] }) %>
<% end %>
</div>
...
<%= f.submit 'Save', class: 'btn btn-primary btn-lg' %>
<% end %>
You also need to add 1 line which enables the nested form logic as:
class Administrator < ActiveRecord::Base
has_one :administrator_role, dependent: :destroy
has_one :role, through: :administrator_role
accepts_nested_attributes_for :role
end
And also change the controller like:
class AdministratorsController < ApplicationController
#....
private
def administrators_params
params.require(:administrator).permit(
:login, :password,
:password_confirmation,
role_attributes: [ :id ]
)
end
end
When you are using has_one association, you get the below method, but not association_id=, and that is what error is saying.
association(force_reload = false)
association=(associate)
build_association(attributes = {})
create_association(attributes = {})
create_association!(attributes = {})