By default, Rails' validates_uniqueness_of does not consider "username" and "USERNAME" to be a collision. If you use MySQL this will lead to issues, since string comparisons are case-insensitive in MySQL.
(If you use PostgreSQL, read this instead.)
Say you have a user model
class User < ActiveRecord::Base
validates_uniqueness_of :name
end
with a unique index in the database.
If you try to create the users "user" and "USER", this will not trigger a validation error, but may fail with an SQL error due to duplicate index key.
You can change Rails' behaviour, by saying
class User < ActiveRecord::Base
validates_uniqueness_of :name, case_sensitive: false
end
When you get an ActiveRecord::RecordNotUnique error (probably in combination with Mysql2::Error: Duplicate entry) for a string field, case sensitivity may be your issue.
Posted by Tobias Kraze to makandra dev (2014-03-20 12:40)