#798 reverted changes should not be marked as changed - Ruby on Rails

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#798 ✓resolved

reverted changes should not be marked as changed

Reported by seanliugm (at gmail) | August 11th, 2008 @ 10:24 AM | in 2.x

attribute_changed? is true even though the value of attribute is changed back to its original value, for example,


>> post = Post.first
=> #<Post id: 1, title: "old", published_at: nil, created_at: "2008-07-30 09:41:03", updated_at: "2008-08-11 08:47:29">
>> post.title
=> "old"
>> post.changed?
=> false
>> post.title_changed?
=> false
>> post.title = 'new'
=> "new"
>> post.changed?
=> true
>> post.title_changed?
=> true
>> post.title_change
=> ["old", "new"]
>> post.title = 'old'
=> "old"
>> post.changed?
=> true
>> post.title_changed?
=> true
>> post.title_change
=> ["old", "old"]

In my opinion, 'title' should not be marked as changed anymore after its value is changed back to the original value. And i think the following reimplementation of method "write_attribute_with_dirty" will solve this issue:


module ActiveRecord
  module Dirty
    private
    def write_attribute_with_dirty(attr, value)
         attr = attr.to_s

         # The attribute already has an unsaved change.
         unless changed_attributes.include?(attr)
           old = clone_attribute_value(:read_attribute, attr)
           changed_attributes[attr] = old if field_changed?(attr, old, value)
         else
           old = changed_attributes[attr]
           changed_attributes.delete(attr)  unless field_changed?(attr, old, value)
         end

         # Carry on.
         write_attribute_without_dirty(attr, value)
    end
  end
end

Comments and changes to this ticket

You flagged this item as spam.
Tom Lea August 11th, 2008 @ 02:16 PM
- Tag set to “activerecord, patch”
+1 easy pitfall fixed

Patch to do this attached, changed format slightly.
- dirty_allows_manual_reversions.diff 2.5 KB
You flagged this item as spam.
seanliugm (at gmail) August 12th, 2008 @ 09:24 AM
- Title changed from “attribute_changed? is true even though the value of attribute is changed to original value” to “reverted changes should not be marked as changed”
Pratik August 12th, 2008 @ 02:07 PM
- Assigned user set to “Jeremy Kemper”
Ryan Bigg August 21st, 2008 @ 05:55 AM
+1 very useful imo
You flagged this item as spam.
Damian Janowski August 21st, 2008 @ 05:58 AM
Can somebody paste a real world example?

Or is this to make your irb sessions "faster"?
You flagged this item as spam.
Tom Lea August 21st, 2008 @ 10:28 AM
Example: Unpaid users can only store a maximum of 300 points, others can store more.
```
MAX_UNPAID_POINTS=300
user = User.find(session[:user_id])
user.points += 10 * user.years_has_been_a_member
user.points = [user.points, MAX_UNPAID_POINTS].min unless user.paid?

update_profile_icon if user.points_changed?
```
Some people may prefer to do the same thing in different styles, assigning from the result of an if or similar, but this is a perfectly valid approach too.
Repository August 28th, 2008 @ 07:21 AM
- State changed from “new” to “resolved”
(from [a3a3067adbd578ad9d145f5a148816ec0460a987]) Dirty: treat two changes resulting in the original value as being unchanged.

[#798 state:resolved]

Signed-off-by: Jeremy Kemper jeremy@bitsweat.net http://github.com/rails/rails/co...
Repository August 28th, 2008 @ 07:21 AM
(from [ad562c58eabfb8b44cb8ac9e87b87a7f998325fd]) Dirty: treat two changes resulting in the original value as being unchanged.

[#798 state:resolved]

Signed-off-by: Jeremy Kemper jeremy@bitsweat.net http://github.com/rails/rails/co...