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Ron Nabuurs
Ron Nabuurs

Reputation: 1556

Django query between startdate and duration

Im working on a Django project and I have to make a query that returns all my record that are active at the moment. The query must be between(startdate, startdate + duration)

I got this query so far, but I don't know how to query startdate + duration < datetime.now()

View:

def home(request):
  active_tasks = Task.objects.all().filter(start_time__lte=datetime.now())
  context = {'active_tasks' : active_tasks}
  return render(request, "main/home.html", context)

Task model:

class Task(models.Model):
  start_time = models.DateTimeField(default=datetime.now())
  duration = models.IntegerField(default=10)

Upvotes: 0

Views: 658

Answers (1)

Shang Wang
Shang Wang

Reputation: 25539

Your code has several defects. First, it's not clear for us what unit does duration have, days, months, years, minutes?

I assume you were using days, but you couldn't query that because you need to convert start_time + duration to datetime and treat it as end time for each record, which is not possible in single query. As @solarissmoke mentioned, you should store the end_time instead. You could keep the duration field if you want, but you could also use a property method to calculate it.

Also, your field definition start_time = models.DateTimeField(default=datetime.now()) would not work, because the default time would only be evaluated once when django starts(when the model is loaded). It's a common mistake that new django developers make. You should change it to:

start_time = models.DateTimeField(default=datetime.now)

This case, datetime.now would be treated as a function object and be called every time you create a new object, which is what you want. Note that django has the built in flag to do that: auto_now_add.

Check this SO answer on more detailed explanation.

Upvotes: 1

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