Develop Reference

500 Undocumented Error: Internal Server Error when returning response in FastAPI

I am using FastAPI to make predictions using a ML model. When I give a task_id and input, the app should add it to the background task and return the response accordingly. However, I am getting Error 500 when I try to do it.
After adding task_id_globally, it started throwing errors before it worked fine.
Error
File ".\app\main.py", line 36, in post
return {'result': response_name[task_id_global]}
TypeError: list indices must be integers or slices, not NoneType
Code
task_id_global = None
#app.get('/predict')
async def predict(task_id:int, background_tasks: BackgroundTasks,solute,solvent):
task_id_global = task_id
if task_id == 0:
background_tasks.add_task(predictions,solute,solvent)
return {'success'}
elif task_id == 1:
background_tasks.add_task(predictions_two,solute)
return {'success'}
else:
return "Give proper task_id"
response_name = [response, attach_drug_name()]
#app.get('/predict_solubility')
async def post():
return {'result': response_name[task_id_global]}

You have set task_id_global to None, and thus, when calling /predict_solubility endpoint, it is trying to retrieve an element from the list using response_name[None]; hence, the error. So you should set task_id_global to 0, which should point to some default value in your response_name list - even if /predict endpoint has not yet been called - or perform a check inside the second endpoint to see whether task_id_global is not None and then decide whether to proceed retrieving an item from the list. Next, inside /predict endpoint declare task_id_global as global before using it (using the global keyword), as, in the way it is currently declared, it is interpreted as a local variable, and hence, the global one never gets affected by any changes occur to task_id_global inside the endpoint (have a look here).
task_id_global = None
#app.get('/predict')
async def predict(task_id:int,solute,solvent):
global task_id_global
task_id_global = task_id
...
Also, depending on your task (e.g., if you have multiple requests concurrently accessing that global variable), you might want to consider other options, such as Redis for instance. Have a look at this answer.

Adding methods gives a 'index out of range error'?

When adding a vital component of methods=["POST", "GET"], my code gives the error:
Line 127, in PatientDashboard
""".format(Data[0][0]))
IndexError: list index out of range
I understand what this error normally means but I don't understand how adding methods affect the size of my list.
#app.route("/PatientDashboard.html", methods=["GET", "POST"])
def PatientDashboard():
Username = (request.args.get("Username"))
Connection = sqlite3.connect(DB)
Cursor = Connection.cursor()
Data = Cursor.execute("""
SELECT *
FROM PatientTable
WHERE Username = '{}'
""".format(Username))
Data = Data.fetchall()
AllAppointments = Cursor.execute("""
SELECT Title, Firstname, Surname, TimeSlot, Date, Status
FROM AppointmentTable
INNER JOIN DoctorTable ON AppointmentTable.DoctorID = DoctorTable.DoctorID
WHERE PatientID = '{}'
""".format(Data[0][0]))
AllAppointments = AllAppointments.fetchall()
The SQL statements work perfectly (database isn't empty) and when adding print(Data) after the first SQL statement there is an output of a nested list.
I have tried troubleshooting by looking at various other questions on stackoverflow but with no luck.
Thank you ever so much in advance.
EDIT 1:
Username = (request.args.get("Username"))
print("Username: ", Username)
Gives the correct output, e.g. Username: nx_prv but after using the POST request the output becomes Username: None.
EDIT 2:
I have managed to fix this using flask.sessions. The problem was that the request.args.get("Username") was getting 'reset' every time.

The scenario I envision: the route was tested with a GET method (because there was not methods argument), and everything was fine. The methods argument was added so a POST could be tested, and it "stopped working". But it really didn't stop working, it's just not built to handle a POST request.
From flask doc on request object the two salient attributes are:
form
A MultiDict with the parsed form data from POST or PUT requests. Please keep in mind that file uploads will not end up here, but
instead in the files attribute.
args
A MultiDict with the parsed contents of the query string. (The part in the URL after the question mark).
So a GET request will "populate" args and a POST request, form. Username will be None from this line Username = (request.args.get("Username")) on a POST request.
You can determine which method by interrogating the method attribute of the request object.
method
The current request method (POST, GET etc.)

geopy openmapquest for Python throws GeocoderInsufficientPrivileges error

I am running the following:
import geopy
geolocator = geopy.geocoders.OpenMapQuest(api_key='my_key_here')
location1 = geolocator.geocode('Madrid')
where my_key_here is my consumer key for mapquest, and I get the following error:
GeocoderInsufficientPrivileges: HTTP Error 403: Forbidden
Not sure what I am doing wrong.
Thanks!

I've also tried the same with the same result. After checking the Library, I found out, that the error is referring to the line, where the request ist build and it seems, that the API Key is not transmitted. If you add no key in the init statement, the api_key='' so I tried to change the line 66 in my own Library of the file: https://github.com/geopy/geopy/blob/master/geopy/geocoders/openmapquest.py to my key.
Still no success! The key itself works, I've tested it with calling the URL that is also called in the Library:
http://open.mapquestapi.com/nominatim/v1/search.php?key="MY_KEY"&format=json&json_callback=renderBasicSearchNarrative&q=westminster+abbey
no idea why this isn't working…
Cheers.kg

I made slight progress with fixing this one. I was able to get the query written correctly, but its the json parsing that kind of have me stumped. Maybe someone knows. I know the url is being sent correctly (I checked it in the browser and it returned a json object). Maybe someone knows how to parse the returned json object to get it to finally work.
Anyways, I had to go in the openmapquest.py source code, and starting from line 66, I made the following modifications:
self.api_key = api_key
self.api = "http://www.mapquestapi.com/geocoding/v1/address?"
def geocode(self, query, exactly_one=True, timeout=None): # pylint: disable=W0221
"""
Geocode a location query.
:param string query: The address or query you wish to geocode.
:param bool exactly_one: Return one result or a list of results, if
available.
:param int timeout: Time, in seconds, to wait for the geocoding service
to respond before raising a :class:`geopy.exc.GeocoderTimedOut`
exception. Set this only if you wish to override, on this call
only, the value set during the geocoder's initialization.
.. versionadded:: 0.97
"""
params = {
'key': self.api_key,
'location': self.format_string % query
}
if exactly_one:
params['maxResults'] = 1
url = "&".join((self.api, urlencode(params)))
print url # Print the URL just to make sure it's produced correctly
Now the task remains to get the _parse_json function working.

Flask - Get key values from request.get_json()

I am attempting to get the key values after requesting json data from ajax POST. I succesfully retrieve the data, however I get the error: " AttributeError: 'unicode' object has no attribute 'keys'".
I have attempted using json.load(data) however, this is also unsuccessful.
#app.route('/sendstats', methods=['GET', 'POST'])
#crossdomain(origin='*', headers='Content-Type')
def go():
data= request.get_json()
keys = sorted(data.keys())
.....
return "Search added"

Have you tried to use json.loads() (note the final s)?

When you set the request body in the first place, you might have put a unicode object there instead of str. this can happen for example if you call json.dumps twice on the same input (first time converts the dict to a str, second time converting it to unicode)

How to POST multiple FILES using Flask test client?

In order to test a Flask application, I got a flask test client POSTing request with files as attachment
def make_tst_client_service_call1(service_path, method, **kwargs):
_content_type = kwargs.get('content-type','multipart/form-data')
with app.test_client() as client:
return client.open(service_path, method=method,
content_type=_content_type, buffered=True,
follow_redirects=True,**kwargs)
def _publish_a_model(model_name, pom_env):
service_url = u'/publish/'
scc.data['modelname'] = model_name
scc.data['username'] = "BDD Script"
scc.data['instance'] = "BDD Stub Simulation"
scc.data['timestamp'] = datetime.now().strftime('%d-%m-%YT%H:%M')
scc.data['file'] = (open(file_path, 'rb'),file_name)
scc.response = make_tst_client_service_call1(service_url, method, data=scc.data)
Flask Server end point code which handles the above POST request is something like this
#app.route("/publish/", methods=['GET', 'POST'])
def publish():
if request.method == 'POST':
LOG.debug("Publish POST Service is called...")
upload_files = request.files.getlist("file[]")
print "Files :\n",request.files
print "Upload Files:\n",upload_files
return render_response_template()
I get this Output
Files:
ImmutableMultiDict([('file', <FileStorage: u'Single_XML.xml' ('application/xml')>)])
Upload Files:
[]
If I change
scc.data['file'] = (open(file_path, 'rb'),file_name)
into (thinking that it would handle multiple files)
scc.data['file'] = [(open(file_path, 'rb'),file_name),(open(file_path, 'rb'),file_name1)]
I still get similar Output:
Files:
ImmutableMultiDict([('file', <FileStorage: u'Single_XML.xml' ('application/xml')>), ('file', <FileStorage: u'Second_XML.xml' ('application/xml')>)])
Upload Files:
[]
Question:
Why request.files.getlist("file[]") is returning an empty list?
How can I post multiple files using flask test client, so that it can be retrieved using request.files.getlist("file[]") at flask server side ?
Note:
I would like to have flask client I dont want curl or any other client based solutions.
I dont want to post single file in multiple requests
Thanks
Referred these links already:
Flask and Werkzeug: Testing a post request with custom headers
Python - What type is flask.request.files.stream supposed to be?

You send the files as the parameter named file, so you can't look them up with the name file[]. If you want to get all the files named file as a list, you should use this:
upload_files = request.files.getlist("file")
On the other hand, if you really want to read them from file[], then you need to send them like that:
scc.data['file[]'] = # ...
(The file[] syntax is from PHP and it's used only on the client side. When you send the parameters named like that to the server, you still access them using $_FILES['file'].)

Lukas already addressed this,just providing these info as it may help someone
Werkzeug client is doing some clever stuff by storing requests data in MultiDict
#native_itermethods(['keys', 'values', 'items', 'lists', 'listvalues'])
class MultiDict(TypeConversionDict):
"""A :class:`MultiDict` is a dictionary subclass customized to deal with
multiple values for the same key which is for example used by the parsing
functions in the wrappers. This is necessary because some HTML form
elements pass multiple values for the same key.
:class:`MultiDict` implements all standard dictionary methods.
Internally, it saves all values for a key as a list, but the standard dict
access methods will only return the first value for a key. If you want to
gain access to the other values, too, you have to use the `list` methods as
explained below.
getList call looks for a given key in the "requests" dictionary. If the key doesn't exist, it returns empty list.
def getlist(self, key, type=None):
"""Return the list of items for a given key. If that key is not in the
`MultiDict`, the return value will be an empty list. Just as `get`
`getlist` accepts a `type` parameter. All items will be converted
with the callable defined there.
:param key: The key to be looked up.
:param type: A callable that is used to cast the value in the
:class:`MultiDict`. If a :exc:`ValueError` is raised
by this callable the value will be removed from the list.
:return: a :class:`list` of all the values for the key.
"""
try:
rv = dict.__getitem__(self, key)
except KeyError:
return []
if type is None:
return list(rv)
result = []
for item in rv:
try:
result.append(type(item))
except ValueError:
pass
return result