在 Django Rest Framework 中，编写自定义函数来过滤数据库

Question

Django : Filter query based on custom function

我引用了底部的问题和答案。我正在尝试编写一个自定义函数来查询我的数据库中的活性胶囊。还有，经理是不是更好class

model.py

class SnapCapsule(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    dateToPost = models.DateTimeField()
    image = models.FileField(upload_to=user_directory_path)
    caption = models.CharField(max_length=20, blank=True)

    def isActivae(currentDate, days=1):
        threshold = timedelta(days=days)
        dateToDelete = capsule.dateToPost.replace(tzinfo=None) + threshold
        if currentDate > self.dateToPost and currentDate < dateToDelte:
            return True
        else:
            return False

views.py

class SnapCapsuleViewSet(viewsets.ModelViewSet):
    """
    API endpoint that allows groups to be viewed or edited.
    """
    capsules = SnapCapsule.objects.all()
    validDates = [ capsule.dateToPost for capsule in capsules if capsule.isActive(datetime.now())]
    queryset = capsules.filter(dateToPost___in=validDates)
    serializer_class = SnapCapsuleSerializer

我遇到的错误是在 views.py 中的列表理解部分。

错误信息

Traceback (most recent call last):
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/db/backends/sqlite3/base.py", line 303, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.OperationalError: no such table: api_snapcapsule

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/core/management/__init__.py", line 371, in execute_from_command_line
    utility.execute()
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/core/management/__init__.py", line 365, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/core/management/base.py", line 332, in execute
    self.check()
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/core/management/base.py", line 364, in check
    include_deployment_checks=include_deployment_checks,
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/core/management/base.py", line 351, in _run_checks
    return checks.run_checks(**kwargs)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/core/checks/registry.py", line 73, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/core/checks/urls.py", line 13, in check_url_config
    return check_resolver(resolver)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/core/checks/urls.py", line 23, in check_resolver
    return check_method()
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/urls/resolvers.py", line 399, in check
    for pattern in self.url_patterns:
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/utils/functional.py", line 36, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/urls/resolvers.py", line 540, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/utils/functional.py", line 36, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/urls/resolvers.py", line 533, in urlconf_module
    return import_module(self.urlconf_name)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/Users/rahmijamalpruitt/Documents/SideProjects/SnapHireMe/backend/snapbackend/snapbackend/urls.py", line 1, in <module>
    from api import views
  File "/Users/rahmijamalpruitt/Documents/SideProjects/SnapHireMe/backend/snapbackend/api/views.py", line 14, in <module>
    class SnapCapsuleViewSet(viewsets.ModelViewSet):
  File "/Users/rahmijamalpruitt/Documents/SideProjects/SnapHireMe/backend/snapbackend/api/views.py", line 19, in SnapCapsuleViewSet
    validDates = [ capsule.dateToPost for capsule in capsules if capsule.isActive(datetime.now())]
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/db/models/query.py", line 272, in __iter__
    self._fetch_all()
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/db/models/query.py", line 1179, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/db/models/query.py", line 53, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1068, in execute_sql
    cursor.execute(sql, params)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/db/backends/utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/Users/rahmijamalpruitt/.local/share/virtualenvs/backend-OsgqpHIp/lib/python3.6/site-packages/django/db/backends/sqlite3/base.py", line 303, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: no such table: api_snapcapsule

Answer 1

尝试将您的代码更改为此

class SnapCapsuleViewSet(viewsets.ModelViewSet):
    """
    API endpoint that allows groups to be viewed or edited.
    """
    queryset = SnapCapsule.objects.all()
    serializer_class = SnapCapsuleSerializer

    def get_queryset(self):
        validDates = [ capsule.dateToPost for capsule in capsules if capsule.isActive(datetime.now())]
        return self.queryset.filter(dateToPost__in=validDates)

重要说明：您的 isActive 查询是一项繁重的操作，对于大型数据库，它会使系统非常慢，请寻找其他解决方案（使用过滤器查找活动项目）使用 dateToPost__range=[from, to]改为查询

在 Django Rest Framework 中，编写自定义函数来过滤数据库

In Django Rest Framework, writing a custom function to filter db

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