Model generation in Ruby on Rails - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of generating a model in Rails?

Generating a model in Rails creates a Ruby class that represents a table in the database. It helps manage data and business logic related to that table.

beginner

Which command generates a new model named 'Article' with a 'title' string and 'body' text fields?

rails generate model Article title:string body:text

intermediate

What files are created when you run the Rails model generation command?

Rails creates a model file (e.g., app/models/article.rb), a migration file to create the database table, and test files for the model.

beginner

Why do you need to run 'rails db:migrate' after generating a model?

Because the migration file created by the model generator defines the database changes. Running 'rails db:migrate' applies those changes to the database.

intermediate

How can you add validations to a Rails model after generation?

You add validation methods inside the model class, like validates :title, presence: true to ensure data meets rules before saving.

What does the Rails model generation command create besides the model file?

A A migration file to create the database table

B A controller file

C A view template

D A stylesheet file

The model generation command creates a migration file to define the database table structure.

Which command applies the database changes after generating a model?

A rails db:migrate

B rails generate migration

C rails server

D rails console

'rails db:migrate' runs the migration files to update the database schema.

How do you specify a string field named 'name' when generating a model?

A name_text

B string:name

C field:name:string

D name:string

The syntax is 'field_name:data_type', so 'name:string' defines a string field named 'name'.

Where is the model file located after generation?

A db/migrate/

B app/controllers/

C app/models/

D app/views/

Model files are stored in the app/models directory.

What is the main role of a Rails model?

A Route web requests

B Manage data and business logic

C Handle user input forms

D Display data to users

Models handle data and business rules in Rails applications.

Explain the steps and commands to create a new model in Rails and make it ready to use with the database.

Think about how Rails connects code to the database.

Describe how you can add rules to a Rails model to check data before saving it.

Consider how to keep data clean and correct.