CODEWITHSUNDEEP
djangodjango-queryset
MiniGunnR
MiniGunnR

Reputation: 5800

How to do Django query to list all the first instances of a date?

I have the following model:

class Attendance(TimeStamped):
    employee_id = models.CharField(max_length=10)
    punch = models.DateTimeField()

The employee punches twice everyday, once to get in and once to log out.

I want to come up with a QuerySet so that I get only the PUNCH INs of the employee. I tried to use distinct() but can't get it to work.

So if an employee goes to office for two days I will have four rows in the model. But I want to only get two rows; only the first result of each date.

How can I do this?

Upvotes: 2

Views: 306

Answers (1)

zaidfazil
zaidfazil

Reputation: 9235

If you really want to distinguish between login and logout then, you need to consider refactoring your models a bit like this..

class Attendance (TimeStamped):
    ..........................
    punch_in = models.BooleanField(default=True)
    punch_out = models.BooleanField(default=False)

    def save(self, *args, **kwargs):
        try:
            login = Attendance.objects.get(modified=self.modified)
            self.punch_out = True
            self.punch_in = False
        except Attendance​.DoesNotExist:
            pass
        return super(Attendance, self).save(*args, **kwargs)

Then you could do queries with,

   Attendance.objects.filter(modified=some_date, punch_in=True)

Assuming the instances aren't meant to be modified. Or you would have to utilise the datetime.combine() , which would make the code more ugly.

I'd recommend to use models.DateField() for the modified field.The above code is under the assumption of the same.

Another option is to add a field similar to created field but of the type models.DateField() which is redundant.

Hope this would work for you..

Upvotes: 1

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