TypeError:“MongoEngine”对象不是subscriptab

Question

在flask应用程序中，我使用MongoEngine作为ORM。 我在python主文件中定义db对象，并尝试从不同的类中重新使用它，方法是从那里导入它。在

这就是我在主py文件中创建db的方法：

db = MongoEngine(app, config={
    'db': "MY_DB",
    'host': "myhost",
    'port': 27017,
    'username': 'user',
    'password': 'password'
})

这是我试图从另一个类（其实例正在从rest入口点使用）中执行的操作：

^{pr2}$

但是在调用入口点时，我遇到了这个错误：

[2019-02-21 10:52:22 +0000] [12] [ERROR] Error handling request module/download/rawdata
Traceback (most recent call last):
  File "/app/env/lib/python3.6/site-packages/gunicorn/workers/base_async.py", line 56, in handle
    self.handle_request(listener_name, req, client, addr)
  File "/app/env/lib/python3.6/site-packages/gunicorn/workers/base_async.py", line 107, in handle_request
    respiter = self.wsgi(environ, resp.start_response)
  File "/app/env/lib/python3.6/site-packages/flask/app.py", line 2309, in __call__
    return self.wsgi_app(environ, start_response)
  File "/app/env/lib/python3.6/site-packages/flask_socketio/__init__.py", line 43, in __call__
    start_response)
  File "/app/env/lib/python3.6/site-packages/engineio/middleware.py", line 67, in __call__
    return self.wsgi_app(environ, start_response)
  File "/app/env/lib/python3.6/site-packages/flask/app.py", line 2295, in wsgi_app
    response = self.handle_exception(e)
  File "/app/env/lib/python3.6/site-packages/flask_cors/extension.py", line 161, in wrapped_function
    return cors_after_request(app.make_response(f(*args, **kwargs)))
  File "/app/env/lib/python3.6/site-packages/flask/app.py", line 1741, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/app/env/lib/python3.6/site-packages/flask/_compat.py", line 35, in reraise
    raise value
  File "/app/env/lib/python3.6/site-packages/flask/app.py", line 2292, in wsgi_app
    response = self.full_dispatch_request()
  File "/app/env/lib/python3.6/site-packages/flask/app.py", line 1815, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/app/env/lib/python3.6/site-packages/flask_cors/extension.py", line 161, in wrapped_function
    return cors_after_request(app.make_response(f(*args, **kwargs)))
  File "/app/env/lib/python3.6/site-packages/flask/app.py", line 1718, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/app/env/lib/python3.6/site-packages/flask/_compat.py", line 35, in reraise
    raise value
  File "/app/env/lib/python3.6/site-packages/flask/app.py", line 1813, in full_dispatch_request
    rv = self.dispatch_request()
  File "/app/env/lib/python3.6/site-packages/flask/app.py", line 1799, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/app/controllers/modules.py", line 51, in download_raw_data
    result = reports.download_raw_data(collection_name, start_time, end_time)
  File "/app/service/services.py", line 114, in download_raw_data
    result = db[collection_name].find(query)
TypeError: 'MongoEngine' object is not subscriptable

我做错什么了？我还想知道为什么会发生这种错误。在

提前谢谢

Answer 1

Mongoengine(...)返回的不是立即的pymongo数据库实例，如果需要，必须使用get_db()：

me = MongoEngine(app, config={...})
...
db = mongo.get_db()
db[collection_name].find(query)

我同意docs是令人困惑的，因为它叫它db，这是误导性的。。。在