RailsHow-ToBeginner · 3 min read

How to Use find_by in Rails: Simple Guide with Examples

In Rails, use find_by to get the first record matching given attributes. It returns the record or nil if none found, unlike find which raises an error.

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Syntax

The find_by method takes one or more attribute-value pairs as arguments and returns the first record matching those attributes.

Example: Model.find_by(attribute: value)

If no record matches, it returns nil instead of raising an error.

ruby

User.find_by(email: 'user@example.com')

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Example

This example shows how to find a user by email using find_by. It returns the user object if found or nil if not.

ruby

class User < ApplicationRecord
end

# Assume a user exists with email 'alice@example.com'
user = User.find_by(email: 'alice@example.com')
if user
  puts "Found user: #{user.email}"
else
  puts "User not found"
end

# Searching for a non-existing email
user2 = User.find_by(email: 'bob@example.com')
puts user2.nil? ? 'User not found' : 'User found'

Output

Found user: alice@example.com User not found

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Common Pitfalls

Using find_by when you expect a record to always exist can cause nil errors if not checked.
Unlike find, find_by does not raise an exception if no record is found.
Passing multiple attributes returns the first record matching all conditions (AND logic).
Do not confuse find_by with where(...).first — find_by is more concise and readable.

ruby

wrong_user = User.find_by(email: 'missing@example.com')
# If you try to call a method on wrong_user without checking, it raises NoMethodError

# Correct way:
user = User.find_by(email: 'missing@example.com')
if user
  puts user.name
else
  puts 'User not found'
end

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Quick Reference

Usage	Description
Model.find_by(attribute: value)	Returns first record matching attribute or nil
Model.find_by(attr1: val1, attr2: val2)	Returns first record matching all attributes (AND)
Returns nil if no match	Does not raise error like find
Use with care to check for nil	Avoid NoMethodError by checking result

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Key Takeaways

Use find_by to get the first record matching given attributes or nil if none found.

Always check if the result is nil before calling methods on it to avoid errors.

find_by accepts multiple attributes and matches all (AND condition).

It is more concise and readable than where(...).first for simple queries.

Unlike find, find_by does not raise an exception if no record exists.