【发布时间】：2021-01-05 20:34:20
【问题描述】：
我找不到任何其他讨论获取 SQLAlchemy 对象的“sa_instance_state”属性错误的线程。在 pytest 方法中调用 Voterlist.query.all() 时出现此错误。当我在 API 或其他任何地方调用 Voterlist.query.all() 时，我没有收到此错误。
这是一个带有前端和 api 蓝图的 Flask 应用程序。前端调用 API。
conftest.py：
class TestConfig(Config):
TESTING = True
SQLALCHEMY_DATABASE_URI = 'sqlite:///test.db'
WTF_CSRF_ENABLED = False
BCRYPT_LOG_ROUNDS = 4
def fill_database():
s0 = Source(title='Catalist')
s1 = Source(title='L2')
sources = [s0, s1]
l0 = Voterlist(description='Test List 0')
l1 = Voterlist(description='Test List 1')
lists = [l0, l1]
return lists, sources
@pytest.fixture(scope='class')
def test_client():
flask_app = create_app(TestConfig)
with flask_app.test_client() as client:
app_context = flask_app.test_request_context()
app_context.push()
db.create_all()
lists, sources = fill_database()
for s in sources:
db.session.add(s)
db.session.commit()
for l in lists:
db.session.add(l)
db.session.commit()
sleep(1)
yield client
db.drop_all()
app_context.pop()
test_api.py：
@pytest.mark.usefixtures('test_client')
class TestLists():
def test_get_lists(self, test_client):
'''Test download all lists.'''
response = test_client.get(url_for('api.lists'))
resplists = response.json['lists']
assert type(resplists) == list
dblists = Voterlist.query.all() <<<< Error here
API方法：
class ListAPI(Resource):
def __init__(self):
self.reqparse = reqparse.RequestParser()
self.fields = ['description', 'vendorquery', 'campaign', 's3key',
'ftimestamp', 'fname', 'source', 'user']
for f in self.fields:
self.reqparse.add_argument(f,
type=str,
location='json')
super(ListAPI, self).__init__()
def get(self):
"""Returns all lists."""
try:
alllists = Voterlist.query.all()
lists = []
for l in alllists:
l = l.__dict__
l.pop('_sa_instance_state', None)
lists.append(l)
return jsonify({'lists': lists})
except Exception as e:
print(e)
abort(400, str(e))
您可以看到，当 API 方法调用 Voterlist.query.all() 时，它可以工作，甚至清楚地包含 _sa_instance_state 属性，否则当我从列表中的每个对象中弹出该属性时，它会抛出相同的错误。
这是 Voterlist 对象的定义：
class Voterlist(db.Model):
id = db.Column(db.Integer, primary_key=True, default=get_time)
description = db.Column(db.String(128))
vendorquery = db.Column(db.String(128))
campaign = db.Column(db.String(128))
s3key = db.Column(db.String(128))
fname = db.Column(db.String(128))
ftimestamp = db.Column(db.Integer)
source = db.Column(db.String(128))
user = db.Column(db.String(128))
status = db.Column(db.Integer, default=0)
def __repr__(self):
return '<List {}: {}>'.format(self.id, self.campaign)
以下是 pytest 的完整输出，以防万一：
=================================================================== test session starts ====================================================================
platform linux -- Python 3.6.9, pytest-6.0.1, py-1.9.0, pluggy-0.13.1
rootdir: /home/alazar66/Downloads/data/rl/rlabs-voter-list-mgr
plugins: anyio-2.0.2
collected 1 item
tests/functional/test_api.py F [100%]
========================================================================= FAILURES =========================================================================
_________________________________________________________________ TestLists.test_get_lists _________________________________________________________________
self = <test_api.TestLists object at 0x74c48f8ff208>, test_client = <FlaskClient <Flask 'app'>>
def test_get_lists(self, test_client):
'''Test download all lists.'''
response = test_client.get(url_for('api.lists'))
resplists = response.json['lists']
assert type(resplists) == list
> dblists = Voterlist.query.all()
tests/functional/test_api.py:15:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
/home/alazar66/.local/lib/python3.6/site-packages/sqlalchemy/orm/query.py:3373: in all
return list(self)
/home/alazar66/.local/lib/python3.6/site-packages/sqlalchemy/orm/loading.py:100: in instances
cursor.close()
/home/alazar66/.local/lib/python3.6/site-packages/sqlalchemy/util/langhelpers.py:70: in __exit__
with_traceback=exc_tb,
/home/alazar66/.local/lib/python3.6/site-packages/sqlalchemy/util/compat.py:182: in raise_
raise exception
/home/alazar66/.local/lib/python3.6/site-packages/sqlalchemy/orm/loading.py:80: in instances
rows = [proc(row) for row in fetch]
/home/alazar66/.local/lib/python3.6/site-packages/sqlalchemy/orm/loading.py:80: in <listcomp>
rows = [proc(row) for row in fetch]
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
row = (1609879216, 'Test List 0', None, None, None, None, None, None, None, 0)
def _instance(row):
# determine the state that we'll be populating
if refresh_identity_key:
# fixed state that we're refreshing
state = refresh_state
instance = state.obj()
dict_ = instance_dict(instance)
isnew = state.runid != runid
currentload = True
loaded_instance = False
else:
# look at the row, see if that identity is in the
# session, or we have to create a new one
identitykey = (
identity_class,
tuple([row[column] for column in pk_cols]),
identity_token,
)
instance = session_identity_map.get(identitykey)
if instance is not None:
# existing instance
> state = instance_state(instance)
E AttributeError: 'Voterlist' object has no attribute '_sa_instance_state'
/home/alazar66/.local/lib/python3.6/site-packages/sqlalchemy/orm/loading.py:532: AttributeError
================================================================= short test summary info ==================================================================
FAILED tests/functional/test_api.py::TestLists::test_get_lists - AttributeError: 'Voterlist' object has no attribute '_sa_instance_state'
==================================================================== 1 failed in 3.89s =====================================================================```
【问题讨论】：
标签： python python-3.x flask sqlalchemy pytest