My point was that annotate might work after the other problems were fixed. Have you re-tested since? If your annotate still doesn't work then perhaps someone with more annotate experience than I will comment.
On Wed, Apr 2, 2014 at 12:04 PM, Justin Holmes <jus...@justinholmes.com>wrote: > No no, the annotate doesn't work - that's the whole reason for my > question. See, the annotate doesn't associate instances with the annotated > attribute, it associated results. > > (BTW, good looking out - I have once again fixed the SO question :-)) > > > On Wed, Apr 2, 2014 at 10:17 AM, Bill Freeman <ke1g...@gmail.com> wrote: > >> 1. You now have a foreign key to Herd, but you don't have a model by >> that name. It's called LlamaHerd. >> >> 2. I was misinterpreting what you wanted (couldn't get past the lack of >> a relationship while reading0. Once the relationship is fixed, your >> original annotate might work. >> >> >> On Tue, Apr 1, 2014 at 6:20 PM, Justin Holmes <jus...@justinholmes.com>wrote: >> >>> You say "use the reverse relation manager in LlamaHerd to build up your >>> annotation," but that answer the question. >>> >>> How can I sort LlamaHerd objects by the DOB of their largest llama? >>> >>> >>> On Tue, Apr 1, 2014 at 6:13 PM, Justin Holmes >>> <jus...@justinholmes.com>wrote: >>> >>>> Yes, absolutely - my bad. I have updated to SO question. I meant the >>>> models to look like: >>>> >>>> class LlamaHerd(models.Model): >>>> shepherd = ForeignKey(User) >>>> >>>> class Llama(models.Model): >>>> size = FloatField() >>>> dob = >>>> FloatField >>>> herd = ForeignKey(Herd, related_name="llamas") >>>> >>>> >>>> >>>> >>>> On Tue, Apr 1, 2014 at 6:09 PM, Bill Freeman <ke1g...@gmail.com> wrote: >>>> >>>>> Aren't you missing a ForeignKey relationship to tell which LlamaHerd a >>>>> Llama belongs to? >>>>> >>>>> Then you would use the reverse relation manager in LlamaHerd to build >>>>> up your annotation. >>>>> >>>>> >>>>> On Tue, Apr 1, 2014 at 5:52 PM, Justin Holmes <jus...@justinholmes.com >>>>> > wrote: >>>>> >>>>>> I have come across this problem in several Django projects, but only >>>>>> just now worked it out in my head enough to make it a cognizable >>>>>> question. >>>>>> >>>>>> I have also posted it on StackOverflow, here: >>>>>> http://stackoverflow.com/questions/22797497/using-the-django-orm-to-order-by-a-value-in-a-distinct-related-item >>>>>> >>>>>> >>>>>> Consider this example: >>>>>> >>>>>> class LlamaHerd(models.Model): >>>>>> shepherd = ForeignKey(User) >>>>>> >>>>>> class Llama(models.Model): >>>>>> size = FloatField() >>>>>> dob = FloatField >>>>>> >>>>>> How can I now make a query to get LlamaHerd objects, sorted by the >>>>>> date of birth of their largest llama? >>>>>> >>>>>> It almost feels like I might be able to use annotate: >>>>>> >>>>>> LlamaHerd.annotate(largest_llama=Max('llama__size')).order_by('largest_llama__dob') >>>>>> >>>>>> ...but the annotate here creates fields with float values, not with >>>>>> the model instances. >>>>>> >>>>>> >>>>>> -- >>>>>> Justin Holmes >>>>>> Chief Chocobo Breeder, slashRoot >>>>>> >>>>>> slashRoot: Coffee House and Tech Dojo >>>>>> New Paltz, NY 12561 >>>>>> 845.633.8330 >>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "Django users" group. >>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>> send an email to django-users+unsubscr...@googlegroups.com. >>>>>> To post to this group, send email to django-users@googlegroups.com. >>>>>> Visit this group at http://groups.google.com/group/django-users. >>>>>> To view this discussion on the web visit >>>>>> https://groups.google.com/d/msgid/django-users/CAMGywB6gkBvhFs%2BP2PrtDah24VDCko8QK-1UCnSGugz_ts1v8g%40mail.gmail.com<https://groups.google.com/d/msgid/django-users/CAMGywB6gkBvhFs%2BP2PrtDah24VDCko8QK-1UCnSGugz_ts1v8g%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>>>> . >>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>> >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Django users" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to django-users+unsubscr...@googlegroups.com. >>>>> To post to this group, send email to django-users@googlegroups.com. >>>>> Visit this group at http://groups.google.com/group/django-users. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/django-users/CAB%2BAj0srKNzRs%3DzbsPm%2BobxLNFCcjRccGSVeYykF1PSnJc-ydQ%40mail.gmail.com<https://groups.google.com/d/msgid/django-users/CAB%2BAj0srKNzRs%3DzbsPm%2BobxLNFCcjRccGSVeYykF1PSnJc-ydQ%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>> >>>> >>>> >>>> -- >>>> Justin Holmes >>>> Chief Chocobo Breeder, slashRoot >>>> >>>> slashRoot: Coffee House and Tech Dojo >>>> New Paltz, NY 12561 >>>> 845.633.8330 >>>> >>> >>> >>> >>> -- >>> Justin Holmes >>> Chief Chocobo Breeder, slashRoot >>> >>> slashRoot: Coffee House and Tech Dojo >>> New Paltz, NY 12561 >>> 845.633.8330 >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Django users" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to django-users+unsubscr...@googlegroups.com. >>> To post to this group, send email to django-users@googlegroups.com. >>> Visit this group at http://groups.google.com/group/django-users. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/django-users/CAMGywB4V3zpbqr7v1kcvOi8%2BoqLPm0nr18dGStaedys494%2BOag%40mail.gmail.com<https://groups.google.com/d/msgid/django-users/CAMGywB4V3zpbqr7v1kcvOi8%2BoqLPm0nr18dGStaedys494%2BOag%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Django users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to django-users+unsubscr...@googlegroups.com. >> To post to this group, send email to django-users@googlegroups.com. >> Visit this group at http://groups.google.com/group/django-users. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/django-users/CAB%2BAj0vE%2Bc8feae_j8v5_U9UHod1RaphytQQASXD1Dwq4RBGDw%40mail.gmail.com<https://groups.google.com/d/msgid/django-users/CAB%2BAj0vE%2Bc8feae_j8v5_U9UHod1RaphytQQASXD1Dwq4RBGDw%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > Justin Holmes > Chief Chocobo Breeder, slashRoot > > slashRoot: Coffee House and Tech Dojo > New Paltz, NY 12561 > 845.633.8330 > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to django-users+unsubscr...@googlegroups.com. > To post to this group, send email to django-users@googlegroups.com. > Visit this group at http://groups.google.com/group/django-users. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-users/CAMGywB4mV1%3DFBeECvwOYP3o-ksm_KNN4s6NX7TpCbVCv70h%2BzQ%40mail.gmail.com<https://groups.google.com/d/msgid/django-users/CAMGywB4mV1%3DFBeECvwOYP3o-ksm_KNN4s6NX7TpCbVCv70h%2BzQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Django users" group. 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