Django: NULL约束
Django: NULL约束
提问于 2022-01-05 11:01:07
我是django的新手，当我想要保存对象列表时会遇到一个错误。有两个对象霍珀(一个)和贸易(许多)。我不知道如何用正确的方式保存它。Hopper对象已经在数据库中。因此，我试图将料斗的id设置为交易对象的外设密钥。
这是保存tadeArray时的错误：
trade.hopper_id django.db.utils.IntegrityError: NULL约束失败：
这意味着当我试图拯救交易时，字段是空的，对吗？
型号(简称)：
class Trade(models.Model):
# Relationships
hopper = models.ForeignKey(Hopper, related_name='trades', on_delete=models.CASCADE) # this should call the error :: django.db.utils.IntegrityError: NOT NULL constraint failed: trade.hopper_id
# Fields
id_db = models.IntegerField(primary_key=True, default=-1)
# ... many attributes
trigger_strategy = models.TextField(default=None)
type = models.TextField(default=None)
class Meta:
# Set the table name.
db_table = 'trade'
# Set default ordering
ordering = ['id']
class Hopper(models.Model):
# Relationships
id_db = models.IntegerField(primary_key=True, default=None)
id = models.IntegerField(default=None)
open_positions_count = models.TextField(default=None)
name = models.TextField(default=None)
exchange = models.TextField(default=None)
hopper_id = models.TextField(default=None)
# ... many attributes
paper_trading = models.IntegerField(default=-1)
start_balance = models.TextField(default=None)序列化程序：
class HopperSerializer(serializers.ModelSerializer):
class Meta:
model = Hopper
fields = ['id',
'open_positions_count',
'name',
'exchange',
'hopper_id',
'subscription_id',
# ... many attributes
'paper_trading',
'start_balance',
]
def create(self, validated_data):
return Hopper.objects.create(**validated_data)
class TradeSerializer(serializers.ModelSerializer):
class Meta:
model = Trade
fields = [
'id',
'exchange',
'currency',
'pair',
# ... many attributes
'buy_id',
'is_short',
'result_short']
extra_kwargs = {
'hopper': {'allow_null': True, 'required': False}
}
def create(self, validated_data):
return Trade.objects.create(**validated_data)views.py (调用这个def并抛出exeption)
@api_view(('POST', 'GET'))
@csrf_exempt
def trades(request, hopper_id):
if request.method == 'POST':
data = request.data
serializer = TradeSerializer(data=data, many=True)
if serializer.is_valid():
hopper = Hopper.objects.get(id=hopper_id)
print(hopper)
serializer.save() # at this point i stuck too. the id of the hopper must be saved with the trades
return Response(serializer.data, status=status.HTTP_201_CREATED)
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)诚挚的问候
回答 1
Stack Overflow用户
回答已采纳
发布于 2022-01-05 11:13:10
class Trade(models.Model):
hopper = models.ForeignKey(Hopper, related_name='trades', on_delete=models.CASCADE, null=True, blank=True)
# ... your other fields我曾多次遇到 NULL约束失败的错误，我通过以上述方式设置字段来解决这个问题。通过设置hopper字段null=True，您是说您的数据库表示该字段可能没有任何值。所以这个错误就会被删除。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/70591766
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