Tutorial: Updating and Deleting Records in Rails

1. Introduction

Welcome to this tutorial! Our goal is to help you understand how to update and delete records in a Ruby on Rails application. By the end of this guide, you will be able to modify and remove records from your database effectively.

What you will learn:
- How to update records
- How to delete records
- Best practices on updating and deleting records

Prerequisites:
- Basic understanding of Ruby on Rails
- Rails installed on your system
- Basic understanding of MVC architecture
- Familiarity with ActiveRecord

2. Step-by-Step Guide

In Rails, we use ActiveRecord, an Object-Relational Mapping (ORM) system, to interact with the database. ActiveRecord provides methods for CRUD operations: Create, Read, Update, Delete.

Updating Records

You can update a record in Rails by first fetching it from the database and then calling the update method on that instance.

user = User.find(1)
user.update(name: "New Name")

Deleting Records

Deleting a record is as simple as calling the destroy method on the instance.

user = User.find(1)
user.destroy

3. Code Examples

Let's dive into some code examples.

Updating a Record

Here's how you can update a record in Rails:

# Fetch the user with ID 1
user = User.find(1)

# Update the user's name
user.update(name: "New Name")

# The `update` method will return true if the record was successfully updated and false otherwise.

Deleting a Record

Here's how you can delete a record in Rails:

# Fetch the user with ID 1
user = User.find(1)

# Delete the user
user.destroy

# The `destroy` method will return the deleted object if the record was successfully deleted and false otherwise.

4. Summary

In this tutorial, we covered how to update and delete records in Rails. We learned about the update and destroy methods provided by ActiveRecord. As next steps, you could learn about how to handle errors during these operations and how to perform these operations on multiple records at a time.

5. Practice Exercises

Let's put what we've learned into practice:

1. Update the email of the user with ID 2 to "newemail@example.com".
2. Delete the user with ID 3.
3. Update the username of all users to "Anonymous".

Solutions:

user = User.find(2)
user.update(email: "newemail@example.com")

user = User.find(3)
user.destroy

User.update_all(username: "Anonymous")

The update_all method updates all records in the table. Be careful with it, as it doesn't trigger ActiveRecord callbacks or validations.