Rails - create and update action don't work - ruby-on-rails

Question

I'm a beginner in Rails, I have a Suplement controller and I can't create or edit a suplement (delete works fine). I'm not getting any errors, just nothing happens when I click and everything's working fine from the console. I tried everything I know (which is not much) and I couldn't find a question like this, similar answers didn't help. I'd appreciate any help, thanks!
class SuplementsController < ApplicationController
before_action :set_suplement, only: [:show, :edit, :update, :destroy]
before_action :authenticate_user!
def index
#suplement = Suplement.all.order("created_at DESC")
end
def new
#suplement = Suplement.new
end
def create
#suplement = Suplement.new(suplement_params)
if #suplement.save
redirect_to '/suplements'
else
render '/suplements/new'
end
end
def show
end
def edit
end
def update
if #suplement.update(suplement_params)
redirect_to '/suplements'
else
redirect_to '/suplements/new'
end
end
def destroy
#suplement.destroy
redirect_to '/suplements'
end
private
def set_suplement
#suplement = Suplement.find(params[:id])
end
def suplement_params
params.require(:suplement).permit(:name,
:number_of_units,
:daily_dosage_in_units,
:number_of_days,
:suplement_cost
)
end
end
Here's a view:
<h1>Create new suplement</h1>
<%= form_for(#suplement) do |f| %>
<%= render 'form', suplement: #suplement %>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
and here's a form partial:
<%= form_for(#suplement) do |f| %>
<% if #suplement.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#suplement.errors.count, "error") %> prohibited this suplement from being saved:</h2>
<ul>
<% #suplement.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 :number_of_units %>
<%= f.text_field :number_of_units %>
</div>
<div class="field">
<%= f.label :daily_dosage_in_units %>
<%= f.text_area :daily_dosage_in_units %>
</div>
<div class="field">
<%= f.label :number_of_days %>
<%= f.text_area :number_of_days %>
</div>
<div class="field">
<%= f.label :suplement_cost %>
<%= f.text_area :suplement_cost %>
</div>
<% end %>
Also my models:
class Suplement < ApplicationRecord
belongs_to :user
validates :name,
:number_of_units,
:daily_dosage_in_units,
:number_of_days,
:suplement_cost,
presence: true
end
and
class User < ApplicationRecord
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
has_many :suplements
end

Answer 1

It looks like the problem is that you have 2 forms.
Uou have a form_for #suplement in your _form.html.erb file and also in your new.html.erb file. Try removing it from new.html.erb so your file looks like this
new.html.erb
<h1>Create new suplement</h1>
<%= render 'form', suplement: #suplement %>
_form.html.erb
<%= form_for(#suplement) do |f| %>
<% if #suplement.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#suplement.errors.count, "error") %> prohibited this suplement from being saved:</h2>
<ul>
<% #suplement.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 :number_of_units %>
<%= f.text_field :number_of_units %>
</div>
<div class="field">
<%= f.label :daily_dosage_in_units %>
<%= f.text_area :daily_dosage_in_units %>
</div>
<div class="field">
<%= f.label :number_of_days %>
<%= f.text_area :number_of_days %>
</div>
<div class="field">
<%= f.label :suplement_cost %>
<%= f.text_area :suplement_cost %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
What I did is:
1) Deleted form_for and submit button inside new.html.erb
2) Added submit button in _form.html.erb, so the variable f is accessible
Also, since you are passing a variable #suplement to partial local variable suplement, you can use the variable suplement inside _form.html.erb file without the # sign
EDIT (Regarding comment):
Your getting User presence validation Error, because from Rails 5.0, belongs_to associations are automatically validated for presence.
If you do not need a user in your suplement object all the time then you should change your association to belongs_to :user, optional: true
OR
if you do need the user, and you always want it to be the current user logged in, then add this to your _form
<%=f.hidden_field :user_id, current_user.id %>
This will use Devise helper method to get the current logged in user and assign it to this hidden field. Don't forget to add this parameter in your controler suplement_params controller method

Answer 2

In the #edit of your controller, you need to set the value of the #suplement variable.
def edit
#suplement = Suplement.find(params[:id])
end
you should also include the above line as the first line in your #update method
def update
#suplement = Suplement.find(params[:id])
if #suplement.update_attributes(suplement_params)
# continued...
end