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new_record? returns nil on records retrieved from database

#1219

I am using a right join to ensure that I always pull back a set of objects via an association even if they haven't been created yet. They have some fields filled in by the join but the ids are blank. When I go to save the object it attempts to do an update instead of a save.

This is because @new_record is not being set, in fact a new_record? returns nil instead of true or false. I added this to my model to ensure a true if it is not set.

def new_record? super || true end

I do not think new_record should be able to return nil, it should return true if @new_record is not set. The alternative is to properly set @new_record to true in this case

Reported by Steve Martocci · October 15th, 2008 @ 05:14 PM

State: committed
Milestone: 2.x
Assigned to: DHH DHH
Importance: none

Activity

  1. Steve Martocci
    Steve Martocci

    actually this is a better solution as the other one will return true on falses not just nils

    def new_record?

    (answer = super).nil? ? true : answer

    end

    October 17th, 2008 @ 04:41 PM

  2. Peter Jaros
    Peter Jaros

    I'm seeing model.new_record? == nil for an AR object I got with a simple find(id). I'm not sure if it's related. It's certainly worrying, since it means that the object isn't == to other objects with the same id and new_record == false.

    October 20th, 2008 @ 04:20 PM

  3. Steve Martocci
    Steve Martocci

    I noticed that too, it actually causes my change not to work....

    I overrode new_method? in the model I was doing joins on to just use this

    hack to fix active record not populating this value from joins

    def new_record?

     id.nil? ? true : false

    end

    and it works for my one specific case.

    October 20th, 2008 @ 04:33 PM

  4. Lar Van Der Jagt
    Lar Van Der Jagt

    This bit me as well. After discussing with Steve it seems that 'new_record?' only works as expected with records which have just been instantiated. If you retrieve a record via 'find', calling 'new_record?' on that object will always return nil.

    Not sure if this is a bug or just an unfortunate side effect of ActiveRecord, but it does seem to violate the principle of least surprise.

    October 22nd, 2008 @ 09:39 PM

  5. Lar Van Der Jagt
    Lar Van Der Jagt
    • Title changed from new_record? not set when using joins to new_record? returns nil on records retrieved from database

    October 22nd, 2008 @ 09:42 PM

  6. Yaroslav Markin
    Yaroslav Markin
    • Tag changed from activerecord, create, joins to activerecord, create, patch, tiny

    Patch attached, I believe that it should return false on existing records as well, unless we have a good reason not to

    December 27th, 2008 @ 01:28 PM

  7. Yaroslav Markin
    Yaroslav Markin
    • Assigned user set to DHH

    December 27th, 2008 @ 01:31 PM

  8. Repository
    Repository
    • State changed from new to committed

    (from [6e98adfc8e19a39fa45d4acd94145d318d151964]) ActiveRecord::Base#new_record? now returns false for existing records (was nil) [#1219 new_record? returns nil on records retrieved from database state:committed]

    Signed-off-by: David Heinemeier Hansson david@loudthinking.com http://github.com/rails/rails/co...

    December 27th, 2008 @ 01:36 PM