To build a job board with Ruby on Rails, you can follow these steps:

1. Set up a new Rails application by running the following command in your terminal:
“`
rails new job_board
“`

2. Change into the project directory:
“`
cd job_board
“`

3. Generate a scaffold for the job model, which will create the necessary files and database migration for the job board:
“`
rails generate scaffold Job title:string description:text company:string location:string
“`

4. Run the database migration to create the jobs table in the database:
“`
rails db:migrate
“`

5. Open the `app/models/job.rb` file and add any validations or associations you need for the job model. For example, you can add a validation to ensure that the title and description are present:
“`ruby
class Job < ApplicationRecord
validates :title, :description, presence: true
end
“`

6. Open the `config/routes.rb` file and add a route for the jobs resource:
“`ruby
Rails.application.routes.draw do
resources :jobs
root ‘jobs#index’
end
“`

7. Open the `app/controllers/jobs_controller.rb` file and update the controller actions as needed. For example, you can add a `new` action to display a form for creating a new job:
“`ruby
class JobsController < ApplicationController
def new
@job = Job.new
end

def create
@job = Job.new(job_params)
if @job.save
redirect_to @job, notice: ‘Job was successfully created.’
else
render :new
end
end

private

def job_params
params.require(:job).permit(:title, :description, :company, :location)
end
end
“`

8. Create the necessary views in the `app/views/jobs` directory. For example, you can create a `new.html.erb` file to display the job creation form:
“`erb