How to Use find Method in Rails ActiveRecord

In Rails, use Model.find(id) to fetch a record by its primary key (usually ID). It raises an error if no record is found, so use find_by(id: id) for a safe alternative that returns nil instead.

Syntax

The find method is called on an ActiveRecord model to retrieve a record by its ID. You pass one or more IDs as arguments.

• Model.find(id): Finds a single record by ID.
• Model.find([id1, id2, ...]): Finds multiple records by IDs.

If the record(s) do not exist, find raises an ActiveRecord::RecordNotFound error.

ruby

User.find(1)
User.find([1, 2, 3])

Example

This example shows how to use find to get a user by ID and handle the case when the user is not found.

ruby

begin
  user = User.find(1)
  puts "User found: #{user.name}"
rescue ActiveRecord::RecordNotFound
  puts "User not found"
end

Output

User found: Alice

Common Pitfalls

Using find without handling exceptions can crash your app if the record is missing. Also, find only works with IDs, not other attributes.

For safer queries, use find_by which returns nil if no record matches.

ruby

user = User.find_by(id: 999)
if user
  puts "User found: #{user.name}"
else
  puts "User not found"
end

Output

User not found

Quick Reference

Method	Description	Returns	Raises Error?
find(id)	Finds record by ID	Record	Yes, if not found
find([id1, id2, ...])	Finds multiple records by IDs	Array of records	Yes, if any not found
find_by(attribute: value)	Finds first record matching attribute	Record or nil	No

Key Takeaways

Use Model.find(id) to get a record by its ID but handle exceptions for missing records.

find raises an error if the record is not found; use find_by for a safe nil return.

find only works with primary keys; use other query methods for different attributes.

Always rescue ActiveRecord::RecordNotFound when using find to avoid app crashes.