将对象添加到许多关系

Question

i'm trying to add ticker values to a currency object using a custom command, but i can't seem to be able to add the ticker to the CurrencyTickerSerializer ? i get following error TypeError: 'QuerySet' object does not support item assignment . I run this command in a specific interval that is suppose to add the ticker into the specific currency, but i guess i need to add something in order to being able to add the ticker into TickerSerializer ?

Command

class Command(BaseCommand):

    def handle(self, *args, **options):
        comparison='DKK'
        url = 'URL'

        page = requests.get(url)
        data = page.json()

        response_data = {}

        for ticker in data:
            currency = Currency.objects.filter(symbol=ticker['symbol'], is_active=True)
            if currency.exists():

                currency['tickers'] = ticker
                serializer = CurrencyTickerSerializer(data=currency)


                if serializer.is_valid():
                    serializer.save()

serializers

class TickerSerializer(serializers.HyperlinkedModelSerializer):
    currency = serializers.PrimaryKeyRelatedField(many=False, queryset=Currency.objects.all())
    class Meta:
        model = Ticker
        fields = ('currency', 'rank', 'price_dkk', 'market_cap_dkk', 'percent_change_1h', 'percent_change_24h', 'percent_change_7d',)


class CurrencyTickerSerializer(serializers.HyperlinkedModelSerializer):
    tickers = TickerSerializer(many=True)
    class Meta:
        model = Currency
        fields = ('id', 'name','symbol', 'tickers', )

Models

class Ticker(models.Model):
    rank = models.IntegerField()
    price_dkk = models.DecimalField(max_digits=20, decimal_places=6)
    market_cap_dkk = models.BigIntegerField()
    percent_change_1h = models.DecimalField(max_digits=4, decimal_places=2)
    percent_change_24h = models.DecimalField(max_digits=4, decimal_places=2)
    percent_change_7d = models.DecimalField(max_digits=4, decimal_places=2)

    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        verbose_name_plural = _('Ticker')

    def __str__(self):
        return self.id

class Currency(models.Model):
    symbol = models.CharField(max_length=4, default='BTC', unique=True)
    name = models.CharField(max_length=20, default='Bitcoin', unique=True)
    img = models.ImageField(upload_to = 'static/img/currencies', blank=True)
    is_active = models.BooleanField(default=False)
    tickers = models.ManyToManyField(Ticker)

    class Meta:
        verbose_name_plural = 'currencies'

    def __str__(self):
        return self.name

Answer 1

let review your code where is this problem .

class Command(BaseCommand):

    def handle(self, *args, **options):
        comparison='DKK'
        url = 'URL'

        page = requests.get(url)
        data = page.json()

        response_data = {}

        for ticker in data:
            currency = Currency.objects.filter(symbol=ticker['symbol'], is_active=True)
            if currency.exists():

                currency['tickers'] = ticker
                serializer = CurrencyTickerSerializer(data=currency)


                if serializer.is_valid():
                    serializer.save()

your code is working until currency['tickers'] = ticker you treat a class as array.use currency.tickers.add(ticker) instate . it will work but not in your case because add function will complain about argument . it's need a instance Ticker class not json data . so know

for ticker in data:
            currency = Currency.objects.filter(symbol=ticker['symbol'], is_active=True)
            if currency.exists():
                tickers = Ticker(...)
                currency.tickers.add(tickers)
                serializer = CurrencyTickerSerializer(data=currency)