how to serialize time with timezone in django-rest-framework's serializer?

Question

I have a Django model:

class Clinic(models.Model):

    NAME_MAX_LENGTH = 150
    name = models.CharField(max_length=NAME_MAX_LENGTH,blank=False,null=False)
    start_at = models.DateTimeField(blank=False,default=timezone.now)

the client sends the start_at field as a time field with timezone like

{
 start_at : "12:40:10+04:30"
} 

I want to convert this time field into the DateTimeField with the current date as the date and then save it into the database as a timezone-aware DateTimeField.

I want to serialize this field and extract timezone info from the input and then create my DateTimeField object. How can I do this in rest_framework serializer?

Answer 1

You can create a custom serializer field for this :

import datetime

from django.utils import timezone

from rest_framework import serializers
from rest_framework.fields import Field


class TimeWithTimezoneField(Field):

    default_error_messages = {
        'invalid': 'Time has wrong format, expecting %H:%M:%S%z.',
    }

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

    def to_internal_value(self, value):
        value_with_date = datetime.datetime.now().strftime('%Y-%m-%d') + ' ' + value
        try:
            parsed = datetime.datetime.strptime(value_with_date, '%Y-%m-%d %H:%M:%S%z')
        except (ValueError, TypeError) as e:
            pass
        else:
            return parsed
        self.fail('invalid')

    def to_representation(self, value):
        if not value:
            return None

        if isinstance(value, str):
            return value

        return timezone.make_naive(value, timezone.utc).strftime("%H:%M:%S+00:00")


class ClinicSerializer(serializers.ModelSerializer):

    start_at = TimeWithTimezoneField()

    class Meta:
        model = Clinic
        fields = [
            'id',
            'name',
            'start_at',
        ]

With your example, start_at: 12:40:10+04:30 will be stored as a timezone aware datetime (in UTC : 08:40:10+00:00)