在下面给出的情况下，如果 Medicine table 包含医学名称，则查询执行正常，但是当对应的 table 上不存在药物名称时，则会发生错误。
匹配的查询不存在
views.py 代码
@api_view(['POST'])
def addPeople(request):
m = People()
m.bp_no = request.POST['bp_no']
m.name = request.POST['name']
m.corporation_name = request.POST['corporation_name']
m.medicine_name = request.POST['medicine_name']
m.no_of_medicine = request.POST['no_of_medicine']
existing = Medicine.objects.get(medicine_name=m.medicine_name).no_of_medicine - int(m.no_of_medicine)
p_key = Medicine.objects.get(medicine_name=m.medicine_name).id
if Medicine.objects.filter(medicine_name=m.medicine_name).exists():
if existing > 0:
m.save()
Medicine.objects.filter(id=p_key).update(no_of_medicine=existing)
return Response({"message": "Successfully Recorded"})
else:
return Response({"message": "Not much Medicine Stored"})
else:
return Response({"message": "Medicine is not Stored"})模型.py
class People(models.Model):
bp_no = models.IntegerField(blank=False,null=False)
name = models.CharField(blank=False,null=False,max_length=200)
corporation_name = models.CharField(blank=False,null=False,max_length=200)
medicine_name = models.CharField(blank=False,null=False,max_length=200)
no_of_medicine = models.IntegerField()
class Medicine(models.Model):
medicine_name = models.CharField(null=False,blank=False,max_length=200)
no_of_medicine = models.IntegerField(null=False,blank=False)
def __str__(self):
return self.medicine_name错误回溯：当 Medicine table 不包含相应的过滤器名称时，将显示此错误
Internal Server Error: /api/add-people/
Traceback (most recent call last):
File "C:\Users\MonirHossain\AppData\Roaming\Python\Python39\site-packages\django\core\handlers\exception.py", line 47, in inner
response = get_response(request)
File "C:\Users\MonirHossain\AppData\Roaming\Python\Python39\site-packages\django\core\handlers\base.py", line 181, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\Users\MonirHossain\AppData\Roaming\Python\Python39\site-packages\django\views\decorators\csrf.py", line 54, in wrapped_view
return view_func(*args, **kwargs)
File "C:\Users\MonirHossain\AppData\Roaming\Python\Python39\site-packages\django\views\generic\base.py", line 70, in view
return self.dispatch(request, *args, **kwargs)
File "C:\Users\MonirHossain\AppData\Roaming\Python\Python39\site-packages\rest_framework\views.py", line 509, in dispatch
response = self.handle_exception(exc)
File "C:\Users\MonirHossain\AppData\Roaming\Python\Python39\site-packages\rest_framework\views.py", line 469, in handle_exception
self.raise_uncaught_exception(exc)
File "C:\Users\MonirHossain\AppData\Roaming\Python\Python39\site-packages\rest_framework\views.py", line 480, in raise_uncaught_exception
raise exc
File "C:\Users\MonirHossain\AppData\Roaming\Python\Python39\site-packages\rest_framework\views.py", line 506, in dispatch
response = handler(request, *args, **kwargs)
File "C:\Users\MonirHossain\AppData\Roaming\Python\Python39\site-packages\rest_framework\decorators.py", line 50, in handler
return func(*args, **kwargs)
File "E:\django\backend\medirecords\api\views.py", line 37, in addPeople
existing = Medicine.objects.get(medicine_name=m.medicine_name).no_of_medicine - int(m.no_of_medicine)
File "C:\Users\MonirHossain\AppData\Roaming\Python\Python39\site-packages\django\db\models\manager.py", line 85, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "C:\Users\MonirHossain\AppData\Roaming\Python\Python39\site-packages\django\db\models\query.py", line 435, in get
raise self.model.DoesNotExist(
api.models.Medicine.DoesNotExist: Medicine matching query does not exist.回答1
我没有对此进行测试，但纯粹就处理未找到的对象而言，我有一个建议您可以尝试简化条件/流程。
.get(): 包裹在 try / except
https://docs.djangoproject.com/en/4.0/ref/models/querysets/#django.db.models.query.QuerySet.get 在未找到时引发 https://docs.djangoproject.com/en/4.0/ref/models/class/#django.db.models.Model.DoesNotExist。
当没有找到时，您需要确定要如何处理它。例如，您可以使用默认后备 value，或引发错误。
在这种情况下，如果找不到现有的药物，代码将失败，所以我会提高它。
@api_view(["POST"])
def addPeople(request):
medicine_name = request.POST["medicine_name"]
try:
medicine = Medicine.objects.get(medicine_name=medicine_name)
except Medicine.DoesNotExist:
return Response({"message": "Not much Medicine Stored"})
m = People()
m.bp_no = request.POST["bp_no"]
m.name = request.POST["name"]
m.corporation_name = request.POST["corporation_name"]
m.medicine_name = medicine_name
m.no_of_medicine = request.POST["no_of_medicine"]
existing = medicine.no_of_medicine - int(m.no_of_medicine)
p_key = medicine.id
if medicine.exists():
if existing > 0:
m.save()
medicine.num_of_medicine = existing
medicine.save(update_fields=["num_of_medicine"])
return Response({"message": "Successfully Recorded"})
else:
return Response({"message": "Not much Medicine Stored"})
else:
return Response({"message": "Medicine is not Stored"})提前移动对象检查
由于请求依赖于
Medicine，所以应该尽早发现。使用
try/catch因为.get()总是在找不到对象时引发替代方法是执行 https://docs.djangoproject.com/en/4.0/ref/models/querysets/#django.db.models.query.QuerySet.exists 或 https://docs.djangoproject.com/en/4.0/ref/models/querysets/#filter + https://docs.djangoproject.com/en/4.0/ref/models/querysets/#first
通过 https://docs.djangoproject.com/en/4.0/ref/models/instances/#django.db.models.Model.save 更新依赖模型，并通过
update_fields将限制字段更新为num_of_medicine。
get_object_or_404()
https://docs.djangoproject.com/en/4.0/topics/http/shortcuts/#get-object-or-404 也可以用来代替前面的 try/catch 块：
from django.shortcuts import get_object_or_404
medicine = get_object_or_404(Medicine.objects.all(), medicine_name=m.medicine_name)
existing = medicine.no_of_medicine - int(m.no_of_medicine)最后说明
我假设这是一个示例，但在 POST 数据中验证 request.POST["no_of_medicine"] 以确保它不是伪造的后端数据源也可能很好。