Menu
I have a quirk(?) with Django queryset filtering:
ipdb> MagazineIssue.objects.filter(id__in=l_magazines.values_list('id')) Out[0]: [] or
ipdb> MagazineIssue.objects.filter(id__in=[l_magazine.id for l_magazine in l_magazines]) Out[0]: [<MagazineIssue: Architecture Australia, Jan 1995 (#1)>] and
ipdb> l_magazines.values_list('id') Out[0]: [(1,)] ipdb> [l_magazine.id for l_magazine in l_magazines] Out[0]: [1] so, how to use values_list()? (to produce):
[1] or is python list comprehension the 'way to go'?
323
filter(tags__in=tags) matches photos that have any of the tags, not only those that has all. Some of those that only has one of the desired tags, may have exactly the amount of tags that you are looking for, and some of those that has all the desired tags, may also have additional tags.
The sql query will be like SELECT * FROM mytable WHERE ids=[1, 3, 6, 7, 9] which is not true. You have to use in operator for this so you query will be like SELECT * FROM mytable WHERE ids in (1, 3, 6, 7, 9) for that Django provide __in operator.
Basically use get() when you want to get a single unique object, and filter() when you want to get all objects that match your lookup parameters.
Django provides a filter() method which returns a subset of data. It accepts field names as keyword arguments and returns a QuerySet object. As database has only one record where name is 'tom' , the QuerySet object contains only a single record.
Try l_magazines.values_list('id', flat=True). That returns a list of ids instead of a list of single id tuples.
67
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
