Got KeyError when attempting to get a value for field `date` on serializer

August 5, 2024

Im trying to do a queryset to show date__month and total of all sale_prices

class RevenueChartListView(ListAPIView):
    queryset = Transactions.objects.annotate(month=ExtractMonth('date')).values('month').annotate(revenue=Sum('sale_price')).order_by('month')
    serializer_class = RevenueSerializer

class RevenueSerializer(serializers.ModelSerializer):
    class Meta:
        model = Transactions
        fields = ['date', 'sale_price']

However I get an error of

"Got KeyError when attempting to get a value for field `date` on serializer `RevenueSerializer`.\nThe serializer field might be named incorrectly and not match any attribute or key on the `dict` instance.\nOriginal exception text was: 'date'."

>Solution :

Your querset does not return model objects but dictionaries with month and revenue as key, so you serialize with:

class RevenueChartSerializer(serializers.Serializer):
    month = models.IntegerField()
    revenue = models.IntegerField()  # or perhaps a FloatField?

and you plug in this serializer:

class RevenueChartListView(ListAPIView):
    queryset = (
        Transactions.objects.annotate(month=ExtractMonth('date'))
        .values('month')
        .annotate(revenue=Sum('sale_price'))
        .order_by('month')
    )
    serializer_class = RevenueChartSerializer

beware that you can simplify the queryset to:

class RevenueChartListView(ListAPIView):
    queryset = (
        Transactions.objects.values(month=ExtractMonth('date'))
        .annotate(revenue=Sum('sale_price'))
        .order_by('month')
    )
    serializer_class = RevenueChartSerializer