Django QuerySet stack filters in script

Question

I have a queryset that only needs to be filtered in certain ways based on specific user provided conditions.

        # construct the base queryset first
    queryset = Spot.objects.values()

    # zero is the default value,
    # so only need to filter if an actual value is provided
    if mindist > 0:
        queryset = queryset.filter(distance >= mindist)
    if maxdist > 0:
        queryset = queryset.filter(distance <= maxdist)

    if starttime != 0:
        queryset = queryset.filter(unix_time >= starttime)
    if endtime != 0:
        queryset = queryset.filter(unix_time <= endtime)

    objects_list = list(queryset)
    return objects_list

Essentially, I am trying to replicate the functionality mentioned in the Django docs https://docs.djangoproject.com/en/1.8/topics/db/queries/#querysets-are-lazy

but with conditions and inside a .py script (instead of the interpreter), but I am getting a 'Name is not defined' error. A few searches indicates that it might be a declaration error with

    queryset = Spot.objects.values()

So I've tried it with other variants like

    queryset = Spot.objects.filter()
    queryset = Spot.objects.all()
    queryset = Spot.objects()

but none of them seems to work.

EDIT : Here is my models.py

    class Spot(models.Model):
         spot_id = models.IntegerField(db_column='Spot_ID', primary_key=True)  # Field name made lowercase.
         unix_time = models.IntegerField(db_column='UNIX_time', blank=True, null=True)  # Field name made lowercase.
         distance = models.IntegerField(db_column='Distance', blank=True, null=True)  # Field name made lowercase.

         class Meta:
             managed = False
             db_table = 'SPOT'

To clarify further. The error comes up for whichever filter that comes right after the initial Spot.objects.values(). For example in the one above,

    queryset = queryset.filter(distance >= mindist)

is the first one, and the error will point to that line with 'distance' not defined . I've tried switching the order around eg putting

   queryset = queryset.filter(unix_time <= endtime)

first instead. but I get the same error, but this time with 'unix_time' not defined .

I've double checked the names and they are all correct. I'm using a

   from .models import *

to import everything, because I also have queries in the script that hits the same database (but different tables) that works perfectly fine, so I'm relatively sure it's not an import issue.

Answer 1

您需要将queryset = Spot.objects而不是queryset = Spot.objects.values()去，以防您导入Spot model 。

Answer 2

SOLVED

So I finally figured out what was wrong. Apparently, filter() does not recognize the standard comparison operators like >= and <=.

Instead it uses Field Lookups to emulate SQL WHERE clauses. So instead of

queryset = queryset.filter(unix_time >= starttime)

I should be doing

queryset = queryset.filter(unix_time___gte = starttime)

Thanks to everyone who tried to help, and I hope this will be useful to anyone who encounters the same problem.