Learn Ruby on Rails: Learn Ruby on Rails Series Part 5

Having previously started a discussion on what Ruby is, how to install Ruby on Rails, an introduction to the Ruby language and an introduction to the Rails framework, now it’s time to start using the Rails framework by creating a simple application.

Simple task management app

This time we will try to create a simple task management application. This app works to record daily tasks, both school assignments and university assignments.

Before that, let’s think about the data needed to create this application. Since this application is related to recording daily tasks, the necessary data is:

1. Task name
2. Task Description
3. Task Category
   This category is for storing course or subject names at school.
4. Deadline (Collection date)

After determining what data is needed, we can conclude that at least this application consists of a model, a controller and several views. Next, we create the project by running the following command in the terminal or command prompt.

mysqlite version

$ rails new homework_management

postgresql translated

$ rails new homework_management -d postgresql

cd homework_management

After creating a new Rails project, all you need to do is create the required controller, model, and views. To create some of these things, Rails provides a very useful feature to create them automatically and simply.

Scaffold, a magical feature in Rails

Scaffolding? What is scaffolding?. The scaffolding is fast lane provided by Rails for creating controllers, models, and associated views. With the scaffold controller, models and views can be created in a single operation.

$ rails generate scaffold Homework homework_name:text category:string deadline:date description:text

The above command means create a homework resource and the table has one column:

1. duty_name form text
2. category form chain (record lessons or subjects)
   
3. deadline form dateAnd
4. description form text

What is the result of this command?

1. File migration
   
2. Model
3. Itinerary
   Scaffold will automatically save the URL that was created as a route resource
4. Controller
5. And in the view, namely the folder homework in application/views,
   index.html.erb, edit.html.erb, show.html.erb,
   new.html.erbAnd _form.html.erb of files
   application/views/assignments

After that, try running the server by typing the following command in terminal or command prompt.

This display is an error display in the Rails framework. What happened ?. What happens is we forget to run the migration file created by the scaffold.

Remember that even though we use scaffolding, to migrate the database files you need to do it yourself by running the following command.

Or

If the above screen appears, it means that a simple task management application has been created.

Only by using scaffolding can the most important interconnected parts be created. But what is the explanation? What if you did it manually? Here is the explanation.

Model

Whengenerate Homework Scaffolding will automatically create a template on app/models/homework.rb. This model can then be used to validate incoming data, etc.
To create a template manually, this can be done as follows:

$ rails generate model Homework

The command automatically creates a template with a name homework.rb Of
application/models with the table migration file.

Controller

Whengenerate Homework Scaffolding will automatically create a controller on app/controllers/homeworks_controller.rb. Apart from that, when executing the scaffold, the controller will automatically create the following methods:

1. hint: displays all data in the table
2. to show: displays data based on settings
3. new: displays the data addition page
4. to modify: displays the data editing page
5. create: the data storage process
6. update: the process of modifying data
7. destroy: the data deletion process

To create a controller manually, you can do so by:

$ rails generate controller Homework

The command automatically creates a controller with a name
homework_controller.rb Of application/controller. If you want to create a controller and create a view, you can do so:

$ rails generate controller Homework index

say “hint” in this command means create a view in app/views/homework/index.html.erb

Migration

From the beginning of the discussion, we often mentioned table migration files. What is migration or migration table in Ruby? Migration is a Ruby feature created to easily create or modify tables in a database. This migration is the one that will result from the construction of scaffolding.

To be able to create a migration file, run the following command.

$ rails generate migration CreateHomeworks

The created migration file will be saved in the db/migrate folder

To be able to migrate, run the following command.

Or

Itinerary

Routes in Rails are like a bridge that works to receive requests from the browser and forward them to the controller orgenerate URL as well as the action when the URL is accessed.

Rails application routes are located in config/routes.rb. When using a scaffold, the scaffold will automatically save the created resources in routes.rb.

resource: homework This means linking all the homework controller methods into one part, and the URL formed from this resource will match the method name.

Example on resources: homework there are methods newthen the resulting URL becomes /homework/new

Then, from the scaffolding results, what URL is produced? To find out which routes are recorded, you can do so by:

Edit root action

To change root action to a certain method, for example root action will be changed to method hint on the controller
homework_controller.rb, This can be done by adding the following script to routes.rb

root "homeworks#index"

Happy coding!!

It’s important to remember that Rails provides scaffolding functionality to make things easier for developers, but don’t use scaffolding without understanding how to manually create controllers, models, migrations, routes, and views.