query.get_meta().fields == query.model._meta.fields, i.e. all the model fields
As far as I understand from reading, deferred_loading is populated only when the queryset is deferred itself, but at the same time if I use .values(*some_fields) instead of .only(*some_fields), its empty again (i.e. its not working for queryset generated by .values()). However I kept digging and I think I found something! compiler.get_select() Returns three values: - a list of 3-tuples of (expression, (sql, params), alias) - a klass_info structure, - a dictionary of annotations where this can be obtained by: queryset.query.get_compiler(using=queryset.db).get_select() >From what I have mange to test so farm its consistent against different types of querysets (deferred, values, +annotations, etc). Thank you for the help so far Matthew. On Thursday, June 15, 2017 at 10:12:26 PM UTC+3, Matthew Pava wrote: > > I have done some digging into the QuerySet API, and I think I may have > found what you are looking for: > MyModel.objects.all().query.get_meta().fields > > You can access the fields that are deferred by using > MyModel.objects.all().query.deferred_loading. Note that the deferred > columns will still be retrieved from the database when requested. > > You can also access annotations by using > MyModel.objects.all().query.annotations, which is an OrderedDict. > > In short, it doesn't look like there is an easy to way to simply access > all the fields that are going to appear in your SELECT clause of your query > from the query itself. You will need to process them. > > And, you're right; selecting the first item in a queryset does seem > hackish. You could even try this: > MyModel.objects.values().first() > which will return None if the queryset is empty, which doesn't have an > attribute of .keys(). > > > -----Original Message----- > From: django...@googlegroups.com <javascript:> [mailto: > django...@googlegroups.com <javascript:>] On Behalf Of Todor Velichkov > Sent: Thursday, June 15, 2017 12:36 PM > To: Django users > Subject: RE: How to get a list of queryset selected fields > > Hello, Matthew Pava, thank you for your answer. > This is probably the solution which I'm going to use if there isn't > anything better, but overall I don't like this approach for a few reasons: > > 1) Dict keys are unordered, I would prefer to be ordered as requested (or > as defined in the Model) I guess with some help from _meta.fields I can > partially solve this) > 2) . values() changes the queryset, I'm not sure if this won't have some > side effects of the final result? > 3) The whole approach of evaluating the queryset + picking the first item > is just looking hacky. But as I already said If there is nothing better I > will go for it. > > -- > 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...@googlegroups.com <javascript:>. > To post to this group, send email to django...@googlegroups.com > <javascript:>. > Visit this group at https://groups.google.com/group/django-users. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-users/7d3ecf53-ccad-4620-b34b-48c1788dba6a%40googlegroups.com. > > > 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 https://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/d3ca2933-9a82-461d-84be-ddc188cc6d94%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
