Thanks. So, in onPreSave, you use kwargs['instance'], assuming it's the instance before saving (which it is, not just in the "current" state). So kwargs['instance'] in both handlers have the same state. If you want to get the current state (the old state, so to speak), you should to something like
sender.objects.get(id=kwargs['instance'].id) This would get you the current state of the that instance. Hope this is clear and helps. Karl Sutt On Sat, May 12, 2012 at 12:00 PM, Alireza Savand <alireza.sav...@gmail.com>wrote: > 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 ? >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Django users" group. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msg/django-users/-/NLEgGtpvQ4cJ. >>>>> To post to this group, send email to django-users@googlegroups.com. >>>>> To unsubscribe from this group, send email to >>>>> django-users+unsubscr...@googlegroups.com. >>>>> For more options, visit this group at >>>>> http://groups.google.com/group/django-users?hl=en. >>>>> >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Django users" group. >>>> To post to this group, send email to django-users@googlegroups.com. >>>> To unsubscribe from this group, send email to >>>> django-users+unsubscr...@googlegroups.com. >>>> For more options, visit this group at >>>> http://groups.google.com/group/django-users?hl=en. >>>> >>> >>> >>> >>> -- >>> + <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> >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Django users" group. >>> To post to this group, send email to django-users@googlegroups.com. >>> To unsubscribe from this group, send email to >>> django-users+unsubscr...@googlegroups.com. >>> For more options, visit this group at >>> http://groups.google.com/group/django-users?hl=en. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Django users" group. >> To post to this group, send email to django-users@googlegroups.com. >> To unsubscribe from this group, send email to >> django-users+unsubscr...@googlegroups.com. >> For more options, visit this group at >> http://groups.google.com/group/django-users?hl=en. >> > > > > -- > + <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> > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To post to this group, send email to django-users@googlegroups.com. > To unsubscribe from this group, send email to > django-users+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/django-users?hl=en. > -- You received this message because you are subscribed to the Google Groups "Django users" group. 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