CODEWITHSUNDEEP
python-3.xdjango-models
user15361826
user15361826

Reputation: 321

How to calculate total duration: Durationfield()

I am unable to calculate total time duration . Here Videos have durations, which is DurationField(). I am confusing about how to calculate total time duration from all videos.

Model

class VideoDetails(BaseModel, Timestamps, SoftDelete):
    video_name = models.CharField(max_length=254, null=False, blank=False)
    video_about_text = models.CharField(max_length=254, null=False, blank=False)
    duration = models.DurationField()
    video = models.OneToOneField(Video, on_delete=models.CASCADE)

class CourseModuleVideos(Timestamps, SoftDelete):
    module_id = models.ForeignKey(CourseModule, on_delete=models.CASCADE)
    video_id = models.ForeignKey(Video, on_delete=models.CASCADE)

class Video(BaseModel, Timestamps, SoftDelete):
    create_date = models.DateTimeField(auto_now_add=True, null=True)

view

z = CourseModuleVideos.objects.filter(module_id=o)
            for zo in z:
                print('o', zo.video_id)
                x = VideoDetails.objects.filter(video=zo.video_id).aggregate(sum('duration'))
                print(x.duration)

Thre is an error

"unsupported operand type(s) for +: 'int' and 'str'"

Give me a solution to overcome this problem.

Upvotes: 1

Views: 342

Answers (1)

willeM_ Van Onsem
willeM_ Van Onsem

Reputation: 477318

You should work with a Sum expression [Django-doc], not with the sum builtin function [Python-doc]. You thus can implement this with the Sum, and access the value in the dictionary with x['duration']

from django.db.models import Sum

# ⋮

x = VideoDetails.objects.filter(video=zo.video_id).aggregate(
    Sum('duration')
)
print(x['duration'])

This is however not very efficient, since you will calculate the duration of each VideoDetails separately, and thus for N videos, make N queries.

We can calculate the sum of the entire module with:

VideoDetails.objects.filter(
    video__coursemodulevideos__module_id=o
).aggregate(sum('duration'))['duration'] or timdelta()

Upvotes: 1

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