How to update created_by field in scaffolding generated code? - ruby-on-rails

Question

I use devise gem for authentication. I generated a scaffold for model M. I would like to update the created_by field with the user id from the login page. How do I achieve this?
I have 2 fields in the model F1 and F2.
The form that scaffold creates shows input for users to enter values for F1 and F2. How do I update the value for created_by field using the current_user from devise? Because the create action seems to be entering only the fields from the form.
<%= form_with(model: M, local: true) do |form| %>
<% if M.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(M.errors.count, "error") %> prohibited this movie from being saved:</h2>
<ul>
<% M.errors.full_messages.each do |message| %>
<li><%= message %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= form.label :F1 %>
<%= form.text_field :F1 %>
</div>
<div class="field">
<%= form.label :F2 %>
<%= form.text_field :F2 %>
</div>
<div class="actions">
<%= form.submit %>
</div>
<% end %>
How to I update the model with current_user value in the above form without exposing that field to the user?
This is my controller:
class MsController < ApplicationController
before_action :set_M, only: [:show, :edit, :update, :destroy]
# GET /Ms
# GET /Ms.json
def index
#Ms = M.all
#categories = #Ms.uniq.pluck(:category)
#Ms_by_category = Hash.new
#categories.each do |category|
#Ms_by_category[category] = M.where(:category => category)
end
end
# GET /Ms/1
# GET /Ms/1.json
def show
end
# GET /Ms/new
def new
#M = M.new
end
# GET /Ms/1/edit
def edit
end
# POST /Ms
# POST /Ms.json
def create
#M = M.new(M_params)
respond_to do |format|
if #M.save
format.html { redirect_to #M, notice: 'M was successfully created.' }
format.json { render :show, status: :created, location: #M }
else
format.html { render :new }
format.json { render json: #M.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /Ms/1
# PATCH/PUT /Ms/1.json
def update
respond_to do |format|
if #M.update(M_params)
format.html { redirect_to #M, notice: 'M was successfully updated.' }
format.json { render :show, status: :ok, location: #M }
else
format.html { render :edit }
format.json { render json: #M.errors, status: :unprocessable_entity }
end
end
end
# DELETE /Ms/1
# DELETE /Ms/1.json
def destroy
#M.destroy
respond_to do |format|
format.html { redirect_to Ms_url, notice: 'M was successfully destroyed.' }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_M
#M = M.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def M_params
params.require(:M).permit(:title, :category, :rating)
end
end

Answer 1

So simple in creating action change your method, for example, you just need to create the client
before_action :authenticate_user!
def create
#client = Client.new(name: params[:name], address: params[:address],created_by: current_user.email )
if #client.save
redirect_to #client
else
render 'new'
end
end
There should be a field like created_by exist in the table.

Answer 2

You need to add users reference to M model and add associations. created_by is not the best name for it. Let imagine that M is abbreviation for Music. In this case you need to create a migration
add_reference :musics, :user
Add to the Music model
belongs_to :user
And to the User model
has_many :musics
And change in the controller
def new
#music = current_user.musics.new
end
def create
#music = current_user.musics.new(M_params)
respond_to do |format|
if #music.save
format.html { redirect_to #music, notice: 'Music was successfully created.' }
format.json { render :show, status: :created, location: #music }
else
format.html { render :new }
format.json { render json: #music.errors, status: :unprocessable_entity }
end
end
end