issue with nested route in Rails 5.1 application - ruby-on-rails

Question

I'm building an application for students to register an absence during a exam.
my routes look like this:
resources :users do
resources :absences
end
the form to create an absence looks like this:
<%= form_for [#user, #absence] do |f| %>
<%= f.label :course_id, "Vak" %>
<%= f.select :course_id, options_for_courses, label: "Vak" %>
<%= f.label :date, "Datum" %>
<%= f.text_field :date %>
<%= f.submit "Afwezigheid aanvragen" %>
<% end %>
the Absence model looks like this:
class Absence < ApplicationRecord
...
belongs_to :user
end
the User model looks like this:
class User < ApplicationRecord
...
has_many :absences
end
The AbsencesController looks like this:
class AbsencesController < ApplicationController
...
def new
#user = current_user
#absence = current_user.absences.build
end
def create
#absence = Absence.create(absence_params)
if #absence.save
redirect_to root_path, notice: "Afwezigheid succesvol aangevraagd"
else
flash[:alert] = "Er was een probleem met het registreren van de afwezigheid"
render :new
end
end
But when I try to register an absence, I get an error in the form:
The error log looks like this:
Started POST "/users/2/absences" for 127.0.0.1 at 2017-09-21 09:51:55 +0200
Processing by AbsencesController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"esW1HeKf+VG8+RC4Zm2F7d8BFewddk6aIssj0Y90s+UC4oTUxpO1iw9hR9M94Jfov5bjeB0aQPRHG0qvENO3Tg==", "absence"=>{"course_id"=>"2", "date"=>"27/09/2017"}, "commit"=>"Afwezigheid aanvragen", "user_id
"=>"2"}
(0.1ms) BEGIN
Course Load (0.3ms) SELECT "courses".* FROM "courses" WHERE "courses"."id" = $1 LIMIT $2 [["id", 2], ["LIMIT", 1]]
(0.1ms) ROLLBACK
(0.1ms) BEGIN
(0.1ms) ROLLBACK
Rendering absences/new.html.erb within layouts/application
Rendered absences/new.html.erb within layouts/application (145.6ms)
Completed 500 Internal Server Error in 616ms (ActiveRecord: 0.9ms)
ActionView::Template::Error - undefined method `absences_path' for #<#<Class:0x007fb911af0420>:0x007fb90baab5d8>
Did you mean? asset_path:
actionpack (5.1.3) lib/action_dispatch/routing/polymorphic_routes.rb:230:in `polymorphic_method'
actionpack (5.1.3) lib/action_dispatch/routing/polymorphic_routes.rb:138:in `polymorphic_path'
actionview (5.1.3) lib/action_view/helpers/form_helper.rb:472:in `apply_form_for_options!'
actionview (5.1.3) lib/action_view/helpers/form_helper.rb:440:in `form_for'
I'm not sure what's going on, have I missed something?
thanks for your help,
Anthony

Answer 1

There is an error while creating your object and you are doing render :new which is rendering the form again but with #user as nil. So what happens that <%= form_for [nil, #absence] do |f| %> makes the path as absences_path which is not present. So either fetch #user in create action too or just use current_user everywhere. Like this:
def new
#user = current_user # You may remove this
#absence = current_user.absences.build
end
def create
#absence = Absence.create(absence_params)
if #absence.save
redirect_to root_path, notice: "Afwezigheid succesvol aangevraagd"
else
#user = current_user # If you don't want to remove this line from new action then add it here too
flash[:alert] = "Er was een probleem met het registreren van de afwezigheid"
render :new
end
end
And in the form if you remove the #user from controller then do it like this:
<%= form_for [current_user, #absence] do |f| %>
Update:
To save the object in create action change this line:
#absence = Absence.create(absence_params)
to
#absence = current_user.absences.build(absence_params)
Your user_id was nil because there was no input box or any hidden field for that and that is correct. You just need to build the object again against the current_user. And I have changed the create to build because create directly saves the object to database instead you want to build it first and then you are trying to save it.
Hope this helps.

Answer 2

You are getting problem in your create method when you are rendering the new because form doesn't getting the #user
add following in your create method & check again
#user = current_user

Answer 3

Okay, you just add return after this line:
redirect_to root_path, notice: "Afwezigheid succesvol aangevraagd"
return
As your log says, you are trying to render :new template at the end of the method, you need to add return to stop it after redirect_to
or delete that line at the end of your create method
render :new
Also change this:
#absence = current_user.absences.build(absence_params)