CodeGenerator

# Ruby on Rails MVC for University App

# == Models ==

# app/models/user.rb
class User < ApplicationRecord
  has_secure_password

enum role: { admin: 0, teacher: 1, student: 2 }

has_many :submissions, foreign_key: :student_id, dependent: :destroy
  has_many :given_grades, class_name: 'Grade', foreign_key: :teacher_id, dependent: :destroy

validates :name, presence: true
  validates :email, presence: true, uniqueness: true
  validates :role, presence: true
end

# app/models/submission.rb
class Submission < ApplicationRecord
  belongs_to :student, class_name: 'User'
  has_one :grade, dependent: :destroy

validates :title, presence: true
  validates :content, presence: true
end

# app/models/grade.rb
class Grade < ApplicationRecord
  belongs_to :submission
  belongs_to :teacher, class_name: 'User'

validates :score, presence: true
  validates :comment, presence: true
end

# == Controllers ==

# app/controllers/application_controller.rb
class ApplicationController < ActionController::Base
  helper_method :current_user

private

def current_user
    @current_user ||= User.find_by(id: session[:user_id]) if session[:user_id]
  end

def require_login
    redirect_to login_path, alert: 'Please log in first' unless current_user
  end

def require_admin
    redirect_to root_path, alert: 'Access denied' unless current_user&.admin?
  end

def require_teacher
    redirect_to root_path, alert: 'Access denied' unless current_user&.teacher?
  end

def require_student
    redirect_to root_path, alert: 'Access denied' unless current_user&.student?
  end
end

# app/controllers/users_controller.rb
class UsersController < ApplicationController
  before_action :require_login
  before_action :require_admin, only: [:new, :create, :index]

def index
    @users = User.all
  end

def new
    @user = User.new
  end

def create
    @user = User.new(user_params)
    if @user.save
      redirect_to users_path, notice: 'User account created successfully.'
    else
      render :new, status: :unprocessable_entity
    end
  end

private

def user_params
    params.require(:user).permit(:name, :email, :password, :password_confirmation, :role)
  end
end

# app/controllers/submissions_controller.rb
class SubmissionsController < ApplicationController
  before_action :require_login
  before_action :require_student, only: [:new, :create]

def index
    if current_user.teacher?
      @submissions = Submission.includes(:student, :grade).all
    elsif current_user.student?
      @submissions = current_user.submissions.includes(:grade)
    else
      @submissions = Submission.includes(:student, :grade).all
    end
  end

def new
    @submission = Submission.new
  end

def create
    @submission = current_user.submissions.build(submission_params)
    if @submission.save
      redirect_to submissions_path, notice: 'Work submitted successfully.'
    else
      render :new, status: :unprocessable_entity
    end
  end

def show
    @submission = Submission.find(params[:id])
  end

private

def submission_params
    params.require(:submission).permit(:title, :content)
  end
end

# app/controllers/grades_controller.rb
class GradesController < ApplicationController
  before_action :require_login
  before_action :require_teacher

def new
    @submission = Submission.find(params[:submission_id])
    @grade = @submission.build_grade
  end

def create
    @submission = Submission.find(params[:submission_id])
    @grade = @submission.build_grade(grade_params)
    @grade.teacher = current_user

if @grade.save
      redirect_to submissions_path, notice: 'Grade added successfully.'
    else
      render :new, status: :unprocessable_entity
    end
  end

private

def grade_params
    params.require(:grade).permit(:score, :comment)
  end
end

# app/controllers/sessions_controller.rb
class SessionsController < ApplicationController
  def new; end

def create
    user = User.find_by(email: params[:email])
    if user&.authenticate(params[:password])
      session[:user_id] = user.id
      redirect_to submissions_path, notice: 'Logged in successfully.'
    else
      flash.now[:alert] = 'Invalid email or password'
      render :new, status: :unprocessable_entity
    end
  end

def destroy
    session[:user_id] = nil
    redirect_to login_path, notice: 'Logged out successfully.'
  end
end

# == Views ==

# app/views/users/index.html.erb
<h1>All Users</h1>
<%= link_to 'Create User', new_user_path %>
<ul>
  <% @users.each do |user| %>
    <li><%= user.name %> - <%= user.email %> - <%= user.role %></li>
  <% end %>
</ul>

# app/views/users/new.html.erb
<h1>Create User</h1>
<%= form_with model: @user do |f| %>
  <div>
    <%= f.label :name %>
    <%= f.text_field :name %>
  </div>
  <div>
    <%= f.label :email %>
    <%= f.email_field :email %>
  </div>
  <div>
    <%= f.label :password %>
    <%= f.password_field :password %>
  </div>
  <div>
    <%= f.label :password_confirmation %>
    <%= f.password_field :password_confirmation %>
  </div>
  <div>
    <%= f.label :role %>
    <%= f.select :role, User.roles.keys.map { |r| [r.titleize, r] } %>
  </div>
  <%= f.submit 'Create User' %>
<% end %>

# app/views/submissions/index.html.erb
<h1>Submissions</h1>
<% if current_user.student? %>
  <%= link_to 'New Submission', new_submission_path %>
<% end %>
<ul>
  <% @submissions.each do |submission| %>
    <li>
      <strong><%= submission.title %></strong> by <%= submission.student.name %><br>
      <%= submission.content %><br>
      <% if submission.grade %>
        Grade: <%= submission.grade.score %><br>
        Comment: <%= submission.grade.comment %><br>
        Teacher: <%= submission.grade.teacher.name %>
      <% elsif current_user.teacher? %>
        <%= link_to 'Grade Submission', new_submission_grade_path(submission) %>
      <% end %>
    </li>
  <% end %>
</ul>

# app/views/submissions/new.html.erb
<h1>Submit Work</h1>
<%= form_with model: @submission do |f| %>
  <div>
    <%= f.label :title %>
    <%= f.text_field :title %>
  </div>
  <div>
    <%= f.label :content %>
    <%= f.text_area :content %>
  </div>
  <%= f.submit 'Submit Work' %>
<% end %>

# app/views/grades/new.html.erb
<h1>Grade Submission</h1>
<p><strong>Title:</strong> <%= @submission.title %></p>
<p><strong>Student:</strong> <%= @submission.student.name %></p>
<p><strong>Content:</strong> <%= @submission.content %></p>

<%= form_with model: [@submission, @grade] do |f| %>
  <div>
    <%= f.label :score %>
    <%= f.number_field :score %>
  </div>
  <div>
    <%= f.label :comment %>
    <%= f.text_area :comment %>
  </div>
  <%= f.submit 'Submit Grade' %>
<% end %>

# app/views/sessions/new.html.erb
<h1>Login</h1>
<%= form_with url: login_path do |f| %>
  <div>
    <%= label_tag :email %>
    <%= email_field_tag :email %>
  </div>
  <div>
    <%= label_tag :password %>
    <%= password_field_tag :password %>
  </div>
  <%= submit_tag 'Login' %>
<% end %>

# == Migrations ==

# db/migrate/20240101000001_create_users.rb
class CreateUsers < ActiveRecord::Migration[7.0]
  def change
    create_table :users do |t|
      t.string :name, null: false
      t.string :email, null: false
      t.string :password_digest, null: false
      t.integer :role, null: false, default: 2

t.timestamps
    end

add_index :users, :email, unique: true
  end
end

# db/migrate/20240101000002_create_submissions.rb
class CreateSubmissions < ActiveRecord::Migration[7.0]
  def change
    create_table :submissions do |t|
      t.string :title, null: false
      t.text :content, null: false
      t.references :student, null: false, foreign_key: { to_table: :users }

t.timestamps
    end
  end
end

# db/migrate/20240101000003_create_grades.rb
class CreateGrades < ActiveRecord::Migration[7.0]
  def change
    create_table :grades do |t|
      t.integer :score, null: false
      t.text :comment, null: false
      t.references :submission, null: false, foreign_key: true
      t.references :teacher, null: false, foreign_key: { to_table: :users }

t.timestamps
    end

add_index :grades, :submission_id, unique: true
  end
end

# == Routes ==

# config/routes.rb
Rails.application.routes.draw do
  root 'submissions#index'

get '/login', to: 'sessions#new'
  post '/login', to: 'sessions#create'
  delete '/logout', to: 'sessions#destroy'

resources :users, only: [:index, :new, :create]
  resources :submissions, only: [:index, :new, :create, :show] do
    resources :grades, only: [:new, :create]
  end
end