The method find_sole_by is particularly useful when you need to retrieve a single record based on a condition but want to ensure that only one matching record exists. If more than one record is found, it raises an exception, helping you catch potential data issues early.
How Does find_sole_by Work?
The find_sole_by method is similar to find_by, but with one important difference: it guarantees that only one record matches the criteria. If multiple records are returned, it raises an ActiveRecord::SoleRecordExceeded exception.
Example
We want to find a user with a specific email
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user = User.find_sole_by(email: "jane.doe@example.com")
- If there is only one user with the email
"jane.doe@example.com", theuserwill be returned. - If no user matches the email, it raises
ActiveRecord::RecordNotFound - If more than one user is found with that email, an exception
ActiveRecord::SoleRecordExceededwill be raised.
Handling Exceptions
Since find_sole_by raises an exception when more than one record is found, it’s a good practice to handle it in your code:
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begin
user = User.find_sole_by(email: "jane.doe@example.com")
rescue ActiveRecord::SoleRecordExceeded
puts "There are multiple users with that email address!"
end
Use Cases for find_sole_by
The find_sole_by method is perfect for situations where you expect a unique record based on a specific attribute (e.g., email or unique token), and you want to ensure data integrity. For example, in an application where emails should be unique, you can use this method to catch any unexpected duplicates early in your code.