我刚开始在 StackOverflow 和 Django 上提问，所以如果我犯了任何错误，我很抱歉。
到目前为止，我已经有了 Django 和 REST Framework 的基本 API。我只想返回添加到数据库的最后一个对象，这可以使用最高 ID 来完成。
这是 models.py:
from django.db import models
class Humidity(models.Model):
value = models.FloatField()
class Temperature(models.Model):
value = models.FloatField()
isFarenheit = models.BooleanField()
我没有任何时间字段，但如果需要，我可以添加它们。
这是序列化器.py:
class HumiditySerializer(serializers.ModelSerializer):
class Meta:
model = Humidity
fields = ('id', 'value')
class TemperatureSerializer(serializers.ModelSerializer):
class Meta:
model = Temperature
fields = ('id', 'value', 'isFarenheit')
这是views.py:
from django.shortcuts import render
from rest_framework import viewsets, permissions
from .models import Humidity, Temperature
from .serializers import HumiditySerializer, TemperatureSerializer
class HumidityView(viewsets.ModelViewSet):
queryset = Humidity.objects.order_by('-id')[0]
serializer_class = HumiditySerializer
class TemperatureView(viewsets.ModelViewSet):
queryset = Temperature.objects.order_by('-id')[0]
serializer_class = TemperatureSerializer
这是错误的回溯:
Traceback (most recent call last):
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\threading.py", line 917, in _bootstrap_inner
self.run()
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\threading.py", line 865, in run
self._target(*self._args, **self._kwargs)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\utils\autoreload.py", line 54, in wrapper
fn(*args, **kwargs)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\core\management\commands\runserver.py", line 117, in inner_run
self.check(display_num_errors=True)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\core\management\base.py", line 390, in check
include_deployment_checks=include_deployment_checks,
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\core\management\base.py", line 377, in _run_checks
return checks.run_checks(**kwargs)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\core\checks\registry.py", line 72, in run_checks
new_errors = check(app_configs=app_configs)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\core\checks\urls.py", line 13, in check_url_config
return check_resolver(resolver)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\core\checks\urls.py", line 23, in check_resolver
return check_method()
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\urls\resolvers.py", line 398, in check
for pattern in self.url_patterns:
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\utils\functional.py", line 80, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\urls\resolvers.py", line 579, in url_patterns
patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\utils\functional.py", line 80, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\urls\resolvers.py", line 572, in urlconf_module
return import_module(self.urlconf_name)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\importlib\__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
File "<frozen importlib._bootstrap>", line 983, in _find_and_load
File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 728, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "C:\Users\usuario\Desktop\Subcarpetas\iot-sensors\iot-sensors-backend\iot-sensors-backend\iotSensors\iotSensors\urls.py", line 21, in <module>
path('', include('api.urls')),
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\django\urls\conf.py", line 34, in include
urlconf_module = import_module(urlconf_module)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\importlib\__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
File "<frozen importlib._bootstrap>", line 983, in _find_and_load
File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 728, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "C:\Users\usuario\Desktop\Subcarpetas\iot-sensors\iot-sensors-backend\iot-sensors-backend\iotSensors\api\urls.py", line 6, in <module>
router.register('humidity', views.HumidityView)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\rest_framework\routers.py", line 75, in register
basename = self.get_default_basename(viewset)
File "C:\Users\usuario\AppData\Local\Programs\Python\Python37-32\lib\site-packages\rest_framework\routers.py", line 162, in get_default_basename
return queryset.model._meta.object_name.lower()
AttributeError: 'Humidity' object has no attribute 'model'
仅当我将views.py从Humidity.objects.all()更改为Humidity.objects.order_by('-id')[0]<时，才会引发此错误 与温度相同。
如何返回最后保存的对象？
最佳答案
由于您的model中没有time或date字段，因此您只能通过id检索最新的对象.
Humidity.objects.all().order_by('-id')[:1]
-id 按相反顺序检索对象。
由于 django 的 QueryDict 对象是延迟加载的，因此只会检索最新的值。
您可以使用last函数来检索最新的对象
Humidity.objects.all().latest()
或者仅通过
检索具有最新id的对象
Humidity.objects.latest('id')
关于django - 仅返回 Django REST Framework 中的最后一个对象，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/59482077/