Okay
here the paste
http://dpaste.de/Oa9cM/
And the Model is just *Poll model* from the tutorial on the django official
document.

On Sat, May 12, 2012 at 2:44 PM, Karl Sutt <k...@sutt.ee> wrote:

> Could you provide some code (paste it to dpaste.org for example)?
> Specifically, it would be useful to see your model definition and signal
> connectors etc.
>
> Karl Sutt
>
>
>
> On Sat, May 12, 2012 at 11:38 AM, Alireza Savand <alireza.sav...@gmail.com
> > wrote:
>
>> Thanks for your answer Karl
>> Actually yes, i want to do some versioning on model instance, but the
>> problem is that the state of the model instance in pre_save is same as at
>> the post_save.
>>
>> On Sat, May 12, 2012 at 2:32 PM, Karl Sutt <k...@sutt.ee> wrote:
>>
>>> Regarding pre_save signal, it is useful for doing something with the
>>> "old" instance. Consider a use case where you might want to "archive" all
>>> changes to, say, the user's profile. Every time a user makes a change to
>>> their profile, you want to save the current state of the profile to another
>>> table, or another database, and then save the new model (which overwrites
>>> the current state and becomes the new current state). This sort of
>>> mechanism is useful for versioning your model instances. The pre_save
>>> signal allows you to create a hook that does precisely that. That is just
>>> one of the use cases, but I'm sure you can think of others.
>>>
>>> Karl Sutt
>>>
>>>
>>>
>>> On Sat, May 12, 2012 at 10:46 AM, Alireza Savand <
>>> alireza.sav...@gmail.com> wrote:
>>>
>>>> Hi
>>>>
>>>> What is the different between pre_save signal and post_save singal.
>>>> I know post_save will emited after model instance saved, and pre_save
>>>> is before the saving the instance[?]
>>>> but what it the point of pre_save when we cannot access the object data
>>>> before the data changes.
>>>> I mean user try to change the model content, like body of a post in a
>>>> blog. using pre_save signal would be reasonable if i can access the post's
>>>> body before the changes or in other word before the actual save() happens.
>>>> If i can't access to data before save() happends, So what is the point
>>>> of pre_save ?
>>>>
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>>
>>
>>
>> --
>> + <https://github.com/Alir3z4/>+ 
>> <https://sourceforge.net/users/alir3z4>+<https://sourceforge.net/projects/yodownet/>
>> + 
>> <https://www.transifex.net/accounts/profile/Alir3z4/>+<https://gist.github.com/Alir3z4>
>> + <http://pastebin.com/u/Alir3z4>+<https://www.ohloh.net/accounts/Alir3z4>
>>
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>
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-- 
+ <https://github.com/Alir3z4/>+
<https://sourceforge.net/users/alir3z4>+<https://sourceforge.net/projects/yodownet/>
+ 
<https://www.transifex.net/accounts/profile/Alir3z4/>+<https://gist.github.com/Alir3z4>
+ <http://pastebin.com/u/Alir3z4>+ <https://www.ohloh.net/accounts/Alir3z4>

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