very nice, thank you. I will look up the book. On Jun 24, 2:37 pm, Daniel Roseman <dan...@roseman.org.uk> wrote: > On Jun 24, 7:01 pm, Sector7B <joe.greenaw...@gmail.com> wrote: > > > Thanks for the feedback and the link, all good stuff! > > I looked at what i had written, and I think a better way to ask the > > question is: > > What are the mechanics behind providing "choice_set.all()"? > > For example i have a field "choice" so having "_set" (concatenated) is > > that generated when i run syncdb somewhere, or is that dynamically > > interpreted at runtime? > > My background leads me to think there would be a choice.set().all(), > > the "_set" seems weird (to me) unless its generated. > > > Thanks again, > > -j > > It's dynamically generated when the model class is defined. Fields can > define a 'contribute_to_class' method, which is responsible for > defining dynamic properties/methods on the model class. When the field > is instantiated - which happens when the class is defined, ie when its > module is first imported - the field's contribute_to_class method is > executed and the related manager is created. You can see the code for > this in django.db.models.fields.related.RelatedField. (Actually you'll > see that contribute_to_class calls do_related_class, which calls > contribute_to_related_class, which sets up the descriptor on the > related model.) > > A very good guide to all this is Marty Alchin's book Pro Django, which > goes into depth as to how the model metaclasses work. > -- > DR.
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