User must exist in Rails 5 - ruby-on-rails

Question

My form partial is as follows:
<%= form_with(model: guitar, local: true) do |form| % >
<% if guitar.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(guitar.errors.count, "error") %> prohibited this
guitar from being saved:</h2>
<ul>
<% guitar.errors.full_messages.each do |message| %>
<li><%= message %></li>
<% end %>
</ul>
</div>
<div class="form-group">
<%= form.label :title %>
<%= form.text_field :title, class: "form-control" %>
</div>
<div class="form-group">
<%= form.label :description %>
<%= form.text_area :description, class: "form-control" %>
</div>
<div class="form-group">
<%= form.submit "Create New Guitar Lesson", class: "btn btn-primary"
%>
</div>
<% end %>
When I try to create a new entry in a table via a form, an error message pops up 'user must exist', which is fine by me.
How do I auto insert (which file / section should I place the code in) current logged in user ID to the form in the background without having the user keying it in manually?
I've pushed the entire app up to the cloud at http://github.com/cheese1884/197451 –

Answer 1

Assuming your field in table is called user_id and you are using Devise.
You should insert the following in your form
<%= form.hidden_field :user_id, value: current_user.id %>
The user's id (taken from Devise's current_user) will be prepopulated in a hidden field that they won't be able to see.

Answer 2

As per doc mentioned of user model
app/models/guitar.rb
class Guitar < ApplicationRecord
belongs_to :user
end
app/models/user.rb
class User < ApplicationRecord
has_many :guitars
end
In rails 5 belongs_to association required by default
which means at the time of creation of each record of guitar user_id is required.
So here by at controller you can solve it by: -
In devise after sign_in there is a helper method which current_user which is current logged_in user
in guitars_controller.rb
def create
new_guitar_record = current_user.guitars.new(guitar_params)
if new_guitar_record.save
#guitar created successfully for current logged in user
else
#current_user.guitar.errors.full_messages
end
end
def guitar_params
params.require(:guitar).permit(:name, :description)
end
Please amend controllers/application_controller as you have messed up devise's current_user and your custom current_user
class ApplicationController < ActionController::Base
protect_from_forgery with: :exception
end
Note: - You can also pass current_user.id by hidden_field :user_id with guitar form but as per security concern it's not good, as user can invoke any user_id via browser.

Answer 3

There are many way to implement this, as i understand you have an user_id field in Guitar model.
Simple solution is need to attach user_id into Guitar object on create action.
In GuitarController go for create and add this line. .merge(user_id: current_user.id).
Remember User must be signed in to get current_user object.
Sample:
#g = Guitar.new(guitar_params.merge(user_id: current_user.id))
Edited
You have many bugs there, 1st of all you need to clean up your controllers.
ApplicationController: remove lines between 6-18. No need it, because Devise gem will provide you these features already.
GuitarsController:
def guitar_params
params.require(:guitar).permit(:name, :description)
end
// guitar view from
<div class="form-group">
<%= form.label :name %>
<%= form.text_field :name, class: "form-control" %>
</div>
// models/user.rb
//add this line
has_many :guitars

Answer 4

If you want to sign in a user in the background, use the sign_in helper inside your controller's action:
sign_in(:user, user)