#29173: Document that Model.save() doesn't refresh fields from the database
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     Reporter:  Xtreak                |                    Owner:  nobody
         Type:  Cleanup/optimization  |                   Status:  new
    Component:  Documentation         |                  Version:  2.0
     Severity:  Normal                |               Resolution:
     Keywords:                        |             Triage Stage:  Accepted
    Has patch:  0                     |      Needs documentation:  0
  Needs tests:  0                     |  Patch needs improvement:  0
Easy pickings:  0                     |                    UI/UX:  0
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Comment (by Xtreak):

 Replying to [comment:1 Tim Graham]:
 > I think that's expected behavior as it would add non-trivial overhead to
 refresh fields from the database after each `save()`. There might be a
 hook that would allow you to do that for your custom field.

 I think we don't need to refresh the value from db. Since we know during
 `get_prep_value` function call the value to be inserted in the database
 and we can update the object with the correct value which is inserted at
 
[https://github.com/django/django/blob/a2e97abd8149e78071806a52282a24c27fe8236b/django/db/models/sql/compiler.py#L1217].
 I might be wrong here due to my limited knowledge of ORM.

 However I also think it's a breaking change and it will be good to make a
 note of this behavior in the documentation than to make this code change.

 Thanks for all the work.

-- 
Ticket URL: <https://code.djangoproject.com/ticket/29173#comment:2>
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