ruby 15 lines · 6 steps

Normalizing user input in Rails models

How a Rails model cleans up attributes before validating them.

Explained by highlit
Rails Intermediate normalization validation data integrity activerecord lambdas
1class User < ApplicationRecord
2 has_secure_password
3 
4 normalizes :email, with: ->(email) { email.strip.downcase }
5 normalizes :phone, with: ->(phone) { phone.gsub(/\D/, "") }
6 normalizes :username, with: ->(username) { username.strip.gsub(/\s+/, "_").downcase }
7 normalizes :website, with: ->(url) { url.blank? ? url : url.sub(%r{\Ahttps?://}i, "") }
8 
9 validates :email, presence: true, uniqueness: true,
10 format: { with: URI::MailTo::EMAIL_REGEXP }
11 validates :phone, length: { is: 10 }, allow_blank: true
12 validates :username, presence: true, uniqueness: true,
13 length: { in: 3..30 },
14 format: { with: /\A[a-z0-9_]+\z/ }
15end
01 / 01
STEP 01

Walkthrough

Space play ←→ step click any line
Three takeaways
  1. 1Normalizing attributes before validation means your rules check clean data, not raw input.
  2. 2Pairing normalization with a matching validation prevents subtle mismatches like case-sensitive uniqueness bugs.
  3. 3Declarative model macros keep data-cleaning logic centralized instead of scattered across controllers.

Related explainers

ruby 
class Order
  class InvalidTransition < StandardError; end
 
  TRANSITIONS = {

A state machine for order transitions in Ruby

state-machine data-driven error-handling
Intermediate 8 steps
php 
<?php
 
namespace App\Http\Controllers;
 

Streaming a filtered CSV export in Laravel

streaming csv-export query-builder
Intermediate 9 steps
ruby 
class CreateOrderItems < ActiveRecord::Migration[7.1]
  def change
    create_table :order_items do |t|
      t.references :order, null: false, foreign_key: { on_delete: :cascade }

Enforcing order-item integrity in Rails

migrations foreign-keys validations
Intermediate 7 steps
ruby 
class Registration < ApplicationRecord
  belongs_to :event
 
  validates :email, presence: true, format: { with: URI::MailTo::EMAIL_REGEXP }

Validating registrations in Rails

validations i18n error-handling
Intermediate 8 steps
ruby 
class ApacheLogParser
  LINE_PATTERN = /\A(?<ip>\S+)\s\S+\s\S+\s\[(?<time>[^\]]+)\]\s"(?<method>[A-Z]+)\s(?<path>\S+)\s(?<protocol>[^"]+)"\s(?<status>\d{3})\s(?<bytes>\d+|-)/
 
  TIME_FORMAT = "%d/%b/%Y:%H:%M:%S %z"

Parsing Apache logs with named captures

regex named-captures parsing
Intermediate 6 steps
ruby 
require "csv"
 
def parse_transaction_row(line)
  fields = CSV.parse_line(line, headers: false, skip_blanks: true)

Parsing one CSV transaction row in Ruby

parsing type-coercion error-handling
Intermediate 6 steps

Share this explainer

Here's the card — post it anywhere.

Normalizing user input in Rails models — share card
Made with highlit — turn any snippet into a walkthrough like this in about a minute.
Explain your code