The uniqueness validator of ActiveRecord has an options to skip validation if the value is nil or blank. Even if I set both parameters to true (the default behaviour) I can create one record with nil and blank before the validation hits. I use the default SQlite3 Database sqlite3-ruby (1.2.5).
Edit for clarification: I get the expected result if I add validates_presence_of to the Model. I thought that the default behaviour of validates_uniqueness_of would make this redundant.
Testcase:
rails validation_test
cd validation_test/
script/generate Model Thing identification:string
rake db:migrate
Content of app/models/thing.rb:
class Thing < ActiveRecord::Base
validates_uniqueness_of :identification
end
Rails console:
script/console
Loading development environment (Rails 2.3.4)
>> Thing.create!
=> #<Thing id: 1, identification: nil, created_at: "2009-09-26 01:49:32", updated_at: "2009-09-26 01:49:32">
>> Thing.create! :identification => ""
=> #<Thing id: 2, identification: "", created_at: "2009-09-26 01:49:42", updated_at: "2009-09-26 01:49:42">
>> Thing.create! :identification => ""
ActiveRecord::RecordInvalid: Validation failed: Identification has already been taken
from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/validations.rb:1090:in `save_without_dirty!'
from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/dirty.rb:87:in `save_without_transactions!'
from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in `save!'
from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/abstract/database_statements.rb:136:in `transaction'
from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:182:in `transaction'
from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in `save!'
from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:208:in `rollback_active_record_state!'
from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in `save!'
from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/validations.rb:1059:in `create!'
from (irb):3
>> Thing.count
=> 2
Why do the first two creations pass?
Thanks
You are mistaken about the default behavior. From the docs:
:allow_nil- If set to true, skips this validation if the attribute is nil (default is false).:allow_blank- If set to true, skips this validation if the attribute is blank (default is false, it includes nil too).
Setting allow_blank to true, I see the following behavior with Rails 2.3.4.
class Thing < ActiveRecord::Base
validates_uniqueness_of :identification, :allow_blank => true
end
>> Thing.create! :identification => ""
=> #<Thing id: 6, identification: "", created_at: "2009-09-26 03:09:48", updated_at: "2009-09-26 03:09:48">
>> Thing.create! :identification => ""
=> #<Thing id: 7, identification: "", created_at: "2009-09-26 03:09:49", updated_at: "2009-09-26 03:09:49">
>> Thing.create! :identification => nil
=> #<Thing id: 8, identification: nil, created_at: "2009-09-26 03:09:52", updated_at: "2009-09-26 03:09:52">
>> Thing.create! :identification => nil
=> #<Thing id: 9, identification: nil, created_at: "2009-09-26 03:09:53", updated_at: "2009-09-26 03:09:53">
Edit: Addressing your clarification.
Adding a validates_presence_of would be correct for what you're trying to do. It's not redundant, since it's checking for a completely different error case. It also has its own error message, which will be important for the user.
class Thing < ActiveRecord::Base
validates_uniqueness_of :identification, :allow_blank => true
validates_presence_of :identification
end