所以，我在flask-restful和fields.Url遇到了一些奇怪的错误，我无法弄清楚为什么会出现这种错误，因为它是随机发生的。正常运行我的应用程序时，它似乎不会发生，并且它只会在测试中随机失败。
值得注意的是，它只发生在POST请求中，并且与GET请求一起使用。
作为参考，所有代码都位于https://github.com/Tehnix/cred-server（已应用临时修复）。
在编组我的数据对象时，似乎创建了一个URL字段失败。完整错误发生在问题的最后。
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/werkzeug/routing.py", line 1678, in build
raise BuildError(endpoint, values, method)
werkzeug.routing.BuildError: ('events_item', {'_sa_instance_state': <sqlalchemy.orm.state.InstanceState object at 0x102df6d68>}, None)
端点定义为，
# FILE: cred/routes.py
api.add_resource(EventsItem, '/events/<int:event_id>', endpoint='events_item')
我使用以下内容编组我的SQLAlchemy对象，
# FILE: cred/resources/events.py
simple_event_fields = {
'id': flask.ext.restful.fields.Integer(attribute='event_id'),
'uri': flask.ext.restful.fields.Url('events_item', absolute=True),
}
fields.Url因某种原因似乎失败了。最后是处理POST请求的资源，
# FILE: cred/resources/events.py
class Events(flask.ext.restful.Resource):
"""Methods going to the /events route."""
def post(self):
"""Create a new event and return the id and uri of the event."""
# Parse the POST args using the parser from flask-restful into event_args
# ...
# Create the event in the database
event = EventModel(
self.client,
event_args['name'],
event_args['location'],
event_args['action'],
event_args['value']
)
# Save the event in the database
db.session.add(event)
db.session.commit()
# Finally, convert the event object into our format by marshalling it,
# and returning the JSON object
return {
'status': 201,
'message': 'Created Event',
'event': marshal(event, simple_event_fields)
}, 201
正如一开始所说的那样，只有在运行测试时才会发生（有时只会），所以它本身并不是关键，但是不必重新运行测试仍然会很好一堆时间只是为了看它是否消失而其他所有人都过去了。
我正在使用Flask-Testing，但除此之外它几乎是单元测试，
# FILE: cred/test/test_events.py
test_event = {
'event': {
'name': 'Temperature',
'location': 'Living Room',
'action': 'Temperature Above Setting',
'value': '5'
}
}
class BaseTestCase(flask.ext.testing.TestCase):
SQLALCHEMY_DATABASE_URI = "sqlite://"
TESTING = True
def create_app(self):
return app
def setUp(self):
"""Create a SQLite database for quick testing."""
cred.database.init_db(cred.database.db)
self.session_key = None
def tearDown(self):
"""Close the database file and unlink it."""
cred.database.db.session.remove()
cred.database.db.drop_all()
@testutil.authenticate('write')
def test_posting_a_complete_event(self):
"""Create a valid new event."""
# Post the request to the test server
response = self.client.post(
'/events',
data=json.dumps(test_event),
content_type='application/json'
)
resp = json.loads(response.data.decode('utf-8'))
# Run self.assertEqual on all items in a dict
testutil.assertEqual(self, {
response.status_code: 201,
resp['status']: 201,
resp['message']: 'Created Event',
'id' in resp['event']: True,
'uri' in resp['event']: True
})
在上文中，由于test_posting_a_complete_event项目，uri会随机失败。
======================================================================
ERROR: Create a valid new event.
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/tehnix/Dropbox/github/Tehnix/cred/cred/test/util.py", line 34, in wrapped
fun(self, *args, **kwargs)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/cred/test/test_events.py", line 37, in test_posting_a_complete_event
resp = json.loads(response.data.decode('utf-8'))
File "/usr/local/Cellar/python3/3.4.2_1/Frameworks/Python.framework/Versions/3.4/lib/python3.4/json/__init__.py", line 318, in loads
return _default_decoder.decode(s)
File "/usr/local/Cellar/python3/3.4.2_1/Frameworks/Python.framework/Versions/3.4/lib/python3.4/json/decoder.py", line 343, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "/usr/local/Cellar/python3/3.4.2_1/Frameworks/Python.framework/Versions/3.4/lib/python3.4/json/decoder.py", line 361, in raw_decode
raise ValueError(errmsg("Expecting value", s, err.value)) from None
nose.proxy.ValueError: Expecting value: line 1 column 1 (char 0)
-------------------- >> begin captured logging << --------------------
cred-server: ERROR: Exception on /events [POST]
Traceback (most recent call last):
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask/app.py", line 1477, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask_restful/__init__.py", line 265, in error_router
return original_handler(e)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask/app.py", line 1381, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask/_compat.py", line 33, in reraise
raise value
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask/app.py", line 1475, in full_dispatch_request
rv = self.dispatch_request()
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask/app.py", line 1461, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask_restful/__init__.py", line 446, in wrapper
resp = resource(*args, **kwargs)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask/views.py", line 84, in view
return self.dispatch_request(*args, **kwargs)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask_restful/__init__.py", line 550, in dispatch_request
resp = meth(*args, **kwargs)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/cred/resources/events.py", line 88, in post
'event': marshal(event, simple_event_fields)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask_restful/__init__.py", line 603, in marshal
return OrderedDict([(envelope, OrderedDict(items))]) if envelope else OrderedDict(items)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/collections/__init__.py", line 56, in __init__
self.__update(*args, **kwds)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/bin/../lib/python3.4/_collections_abc.py", line 602, in update
for key, value in other:
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask_restful/__init__.py", line 602, in <genexpr>
for k, v in fields.items())
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask_restful/fields.py", line 294, in output
o = urlparse(url_for(endpoint, _external=self.absolute, **data))
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask/helpers.py", line 312, in url_for
return appctx.app.handle_url_build_error(error, endpoint, values)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask/app.py", line 1641, in handle_url_build_error
reraise(exc_type, exc_value, tb)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask/_compat.py", line 33, in reraise
raise value
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/flask/helpers.py", line 305, in url_for
force_external=external)
File "/Users/tehnix/Dropbox/github/Tehnix/cred/env/lib/python3.4/site-packages/werkzeug/routing.py", line 1678, in build
raise BuildError(endpoint, values, method)
werkzeug.routing.BuildError: ('events_item', {'_sa_instance_state': <sqlalchemy.orm.state.InstanceState object at 0x102df6d68>}, None)
答案 0 :(得分：0)
您需要在＆＃39; fields.Url＆＃39;内分配events_items。在回来之前。
此链接How to add fields url for nested output fields in flask restful解释了更多
但如果您使用的是蓝图，请添加＆＃34; .＆＃34;到fields.Url例如
'uri': fields.Url('.events_items')
ref https://github.com/flask-restful/flask-restful/issues/266#issuecomment-46678118