问django“无效pk \”1\- object不存在。是否存在？

EN

class ReturnItemsSerializer(serializers.ModelSerializer):
    returns = serializers.PrimaryKeyRelatedField(queryset=ReturnItems.objects.all())
    returnreasons = serializers.PrimaryKeyRelatedField(queryset=ReturnReasons.objects.all())

    class Meta:
        model = ReturnItems
        fields = [
            "id",
            "updated_at",
            "returns",
            "returnreasons"

        ]
        depth = 1


class ReturnItems(models.Model):  
    updated_at = models.CharField(max_length=256, null=True, blank=True)
    returns = models.ForeignKey(Returns,on_delete=models.CASCADE, related_name='returnitems',  null=True, blank=True)
    returnreasons = models.ForeignKey(ReturnReasons,on_delete=models.CASCADE, related_name='returnitems', null=True, blank=True)



{
"returnreasons": 1,
"returns": 1
}


{
"returns": [
    "Invalid pk \"1\" - object does not exist."
],
"returnreasons": [
    "Invalid pk \"1\" - object does not exist."
]
}