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validates_uniqueness_of does not take field length into account

#1042

With the following Event model:


class CreateEvents < ActiveRecord::Migration
  def self.up
    create_table :events do |t|
      t.string :title, :limit => 5
      t.text :description
      t.datetime :time
      t.timestamps
    end
  end

  def self.down
    drop_table :events
  end
end

class Event < ActiveRecord::Base

  validates_uniqueness_of :title

end

I can do something along the lines of:

e = Event.create(:title => "abcde") => #e2 = Event.create(:title => "abcdefgh") => #Event.find_all_by_title("abcde") => [#, #]

The titles are unique until you apply the :limit => 5 but validates_uniqueness_of doesn't take this into account. This leaves two events with the title "abcde" in the database (MySQL, not SQLite, which doesn't enforce varchar limits).

Reported by Arthur Klepchukov · September 14th, 2008 @ 10:20 AM

Activity

Arthur Klepchukov

Sorry, the second part got mangled. Here it is again.

I can do something along the lines of:


>> e = Event.create(:title => "abcde")
=> #<Event id: 1, title: "abcde", description: nil, time: nil, created_at: "2008-09-14 09:01:14", updated_at: "2008-09-14 09:01:14">
>> e2 = Event.create(:title => "abcdefgh")
=> #<Event id: 2, title: "abcdefgh", description: nil, time: nil, created_at: "2008-09-14 09:01:31", updated_at: "2008-09-14 09:01:31">
>> Event.find_all_by_title("abcde")
=> [#<Event id: 1, title: "abcde", description: nil, time: nil, created_at: "2008-09-14 09:01:14", updated_at: "2008-09-14 09:01:14">, #<Event id: 2, title: "abcde", description: nil, time: nil, created_at: "2008-09-14 09:01:31", updated_at: "2008-09-14 09:01:31">]

September 14th, 2008 @ 10:23 AM

Arthur Klepchukov
I realize that this could be taken care of if I set validates_length_of :title, :maximum => 5 in my model. However, I don't like having to repeat that (since I specified it in the migration) and I'm still worried about the database being in an inconsistent state.

A basic fix to this could be adding the following after line 669 in lib/active_record/validations.rb:
```
value = value[0, finder_class.columns_hash[attr_name.to_s].limit]
```
September 14th, 2008 @ 10:59 AM
Arthur Klepchukov
I went ahead and submitted a patch.

September 14th, 2008 @ 11:16 AM
Pratik
- Assigned user set to Pratik
- State changed from new to incomplete
That's a good catch and it looks very tricky as well.

I can't see any patch. Could you please upload a patch here - http://rails.lighthouseapp.com/p... ?

Thanks.

December 20th, 2008 @ 06:11 PM
Arthur Klepchukov
- Tag changed from activerecord, bug, migrations to activerecord, bug, limit, migrations, validates_uniqueness_of, validation
This patch makes ActiveRecord's validates_uniqueness_of take :limit into account for :string columns.
- uniquness-with-length.diff 3.12 KB
December 24th, 2008 @ 04:47 AM
Arthur Klepchukov
- Tag changed from activerecord, bug, limit, migrations, validates_uniqueness_of, validation to activerecord, bug, limit, migrations, patch, validates_uniqueness_of, validation
Tagged as patch.

December 24th, 2008 @ 04:50 AM
Pratik
- State changed from incomplete to open
December 24th, 2008 @ 05:01 AM
Daniel Schierbeck
Nice patch, with good, concise comments and a simple-to-follow test. +1.

December 30th, 2008 @ 04:36 PM
Repository
- State changed from open to resolved
(from [ccb0a92fa2ba0bf7be50033090c3a861e6d907be]) Ensure validates_uniqueness_of considers limit on the field. [#1042 state:resolved]

Signed-off-by: Pratik Naik pratiknaik@gmail.com http://github.com/rails/rails/co...

March 7th, 2009 @ 01:52 PM
Jacob Burkhart
This needs to be fixed to support unicode, see #2653

May 15th, 2009 @ 06:29 PM