Rails 'required: true' does not work fully - ruby-on-rails

Question

I have a simple_form with a grouped collection select and two input fields. I have a required: true on both fields, but it still allows empty input through. The little 'required' asterisk appears next to the field name, but that's it. Is there any way I can prevent empty input from going through the form?
new.rb
<h1>New Article</h1>
<%= render 'form', article: #article %>
<%= link_to 'Back', articles_path(category_id: params[:category_id]) %>
_form.rb
<%= simple_form_for(article, html: {class: 'form-vertical'}) do |f| %>
<% if article.errors.any? %>
<div id="error_explanation">
<h4><%= pluralize(article.errors.count, "error") %> prohibited this article from being saved:</h4>
<ul>
<% article.errors.full_messages.each do |message| %>
<li><%= message %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%# field being selected, parent collection, subcollection, displayed, key, value %>
<%= f.grouped_collection_select :subcategory_id, Category.all,:subcategories,:name, :id,:name, {required: true} %>
<%= f.input :title, required: true %>
<%= f.input :content, input_html: { rows: 20 }, required: true%>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
articles_controller.rb
class ArticlesController < ApplicationController
before_action :set_article, only: [:show, :edit, :update, :destroy]
# GET /articles
# GET /articles.json
def index
if params[:category_id].blank? && params[:subcategory_id].blank?
#articles = Article.all.order("created_at DESC")
elsif params[:subcategory_id].blank?
#articles = Article.where(category_id: params[:category_id])
else
#articles = Article.where(subcategory_id: params[:subcategory_id]).order("created_at DESC")
end
end
# GET /articles/1
# GET /articles/1.json
def show
end
# GET /articles/new
def new
#article = Article.new
end
# GET /articles/1/edit
def edit
end
# POST /articles
# POST /articles.json
def create
#parameters = article_params
#parameters[:category_id] = Subcategory.find(#parameters[:subcategory_id]).category_id
#article = Article.new(#parameters)
respond_to do |format|
if #article.save
format.html { redirect_to #article, notice: 'Article was successfully created.' }
format.json { render :show, status: :created, location: #article }
else
format.html { render :new }
format.json { render json: #article.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /articles/1
# PATCH/PUT /articles/1.json
def update
respond_to do |format|
if #article.update(article_params)
format.html { redirect_to #article, notice: 'Article was successfully updated.' }
format.json { render :show, status: :ok, location: #article }
else
format.html { render :edit }
format.json { render json: #article.errors, status: :unprocessable_entity }
end
end
end
# DELETE /articles/1
# DELETE /articles/1.json
def destroy
#article.destroy
respond_to do |format|
format.html { redirect_to root_path, notice: 'Article was successfully destroyed.' }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_article
#article = Article.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def article_params
params.require(:article).permit(:title,:content,:subcategory_id)
end
end

Answer 1

As per simple documentation of rails. Your model should look like this(suppose i wanted to validate presence of first_name last_name and compnay_name):
class User < ApplicationRecord
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :validatable
validates :company_name, presence: true
validates :first_name, presence: true
validates :last_name, presence: true
end
Now after this you are ready to go, presence: true will validate data before saving it to the database. A good practice is to add a validation to the front end too. which is add require: true to your form_for helper.
<div class="field">
<%= f.label :last_name %><br />
<%= f.text_field :last_name, autofocus: true, required: true ,autocomplete: "email", class: "border p-3 w-100 my-2" %>
</div>

Answer 2

You need to use validations, that logic is done inside the model.
Make sure you read and undertand the ActiveRecord Validations Guide because it will save you a lot of time.
Example taken from the guide:
class Person < ApplicationRecord
validates :name, presence: true
end
Person.create(name: "John Doe").valid? # => true
Person.create(name: nil).valid? # => false
Basically when the object is saved, it runs the validations and if it's not valid it will fill the errors variable with the messages.

Answer 3

Simple form documentation states...
By default all inputs are required. When the form object has presence
validations attached to its fields, Simple Form tells required and
optional fields apart. For performance reasons, this detection is
skipped on validations that make use of conditional options, such as
:if and :unless.
Which means that all you need to do is add into your model/article.rb file
class Article < ActiveRecord::Base
validates :title, presence: true
validates :content, presence: true