Develop Reference

"AttributeError: 'module' object has no attribute" - Can someone explain the meaning of this error message?

I'm trying to get the ODB library working. In the documentation at https://python-obd.readthedocs.io/en/latest/ it lists the following code:
import obd
connection = obd.OBD("/dev/ttyUSB0") # connects to USB or RF port
cmd = obd.commands.SPEED # select an OBD command (sensor)
response = connection.query(cmd) # send the command, and parse the response
print(response.value) # returns unit-bearing values thanks to Pint
print(response.value.to("mph")) # user-friendly unit conversions
When I put this in a file called test.py and I run it:
python2 test.py
I get the following error message:
Traceback (most recent call last):
File "test.py", line 1, in <module>
import obd
File "/home/ubuntu/obd.py", line 3, in <module>
AttributeError: 'module' object has no attribute 'OBD'
Stackoverflow comes up with several iterations of this error message, but none clearly explain the problem, only giving specific solutions to those libraries.
I guess it's obvious that I'm new to Python, and I'm having trouble interpreting this error message, even after several hours of writing several small Python programs. I am of course also interested in why the error message is so un-intuitive to a newcomer and where I can gain the common knowledge I might be missing, and I guess this is as good a case to discover that through as any.

So far I have figured out the following:
<module> refers to the name of my python script that I am trying to run.
The mistake I made at first, was to name my test.py file, initially obd.py. This conflicted with the import obd as it was trying to import the file itself - even after I deleted it! The reason was that when I tried to run it the first time, it created a file called obd.pyc - and even though obd.py was no longer there, import OBD found the initially created obd.pyc and tried to import that - which of course does not contain the OBD object from the library I was trying to use.
This is not the detailed answer I'm looking for, so please add a more detailed explanation - or a link to how Python compiling works, if you can.

sqlanydb windows could not load dbcapi

I am trying to connect to a SQL Anywhere database via python. I have created the DSN and I can use command prompt to connect to the database using dbisql - c "DNS=myDSN". When I try to connect through python using con = sqlanydb.connect(DSN= "myDSN")
I get
`Traceback (most recent call last):
File "<pyshell#5>", line 1, in <module>
con = sqlanydb.connect(DSN= "RPS Integration")
File "C:\Python27\lib\site-packages\sqlanydb.py", line 522, in connect
return Connection(args, kwargs)
File "C:\Python27\lib\site-packages\sqlanydb.py", line 538, in __init__
parent = Connection.cls_parent = Root("PYTHON")
File "C:\Python27\lib\site-packages\sqlanydb.py", line 464, in __init__
'libdbcapi_r.dylib')
File "C:\Python27\lib\site-packages\sqlanydb.py", line 456, in load_library
raise InterfaceError("Could not load dbcapi. Tried: " + ','.join(map(str, names)))
InterfaceError: (u'Could not load dbcapi. Tried: None,dbcapi.dll,libdbcapi_r.so,libdbcapi_r.dylib', 0)`

I was able to resolve the problem. I was never able to use the sqlanydb.connect. I ended up using pyodbc. So my final connection string was con = pydobc.connect(dsn="myDSN"). I think that sqlanydb is only fully functional with sqlanydb 17 and I was using a previous version.

Depending on how Sybase is locally installed, it could also be that the Python module really cannot find the (correct) library when looking up dbcapi.dll in your PATH. A quick fix for that is to create a new SQLANY_API_DLL environment variable (that's the initial None in the names the error message says it tried using; it takes priority over all the others) containing the correct path, usually something like %SQLANY16%\Bin64\dbcapi.dll depending on what version you have installed (Sybase usually creates an environment variable pointing to its installation folder on a per version basis).

One way to encounter the backtrace shown by the OP is running 64-bit Python interpreter, which is unable to load the 32-bit dbcapi.dll. Try launching with "py -X-32" to force a 32-bit engine, or reinstall using a 32-bit python engine.
Unfortunately sqlanydb's code that tries to be smart about finding dbcapi also ends up swallowing the exceptions thrown during loading. The sqlanydb author probably assumed that failure to load implies file not found, which isn't always the case.

I was stoked in this same problem, both windows system32 and 64.
I'm using Python 3.9 and I found that since Python 3.8 the cdll.LoadLibrary function does no longer search PATH to find library files.
To fix this, I created the enviroment variable SQLANY_API_DLL pointing to the route of sqlanywhere installation, in my case version 17, bin32 or bin64 depending on your system.

PyWin32 get network information/statistics

I am trying to get Network Statistics for my Windows 7 system using PyWin32.
The steps I followed:
1) Run COM MakePy utility and than select network list manager 1.0
type library under type library.
2) Above process generated this python file.
Now the problem I am facing is after the above two steps what should be my next step. I tried a couple of things like:
I copied the CLSID = IID('{DCB00000-570F-4A9B-8D69-199FDBA5723B}') line from the above generated python file and used it like
>>> import win32com
>>> obj = win32com.client.gencache.GetClassForCLSID("{DCB00000-570F-4A9B-8D69-199FDBA5723B}")
>>> obj.GetConnectivity()
Traceback (most recent call last):
File "<interactive input>", line 1, in <module>
TypeError: unbound method GetConnectivity() must be called with INetworkListManager instance as first argument (got nothing instead)
When I do obj.method() it show a list of all available method.
So, now I have no idea what to do or how to proceed and what is the general process of using Type library with pywin32.
The above task is just a part of learning process on how to use PyWin32,COM MakePy utility.
Is this even achievable using pywin32.?

You'll need to use win32com.client.Dispatch to actually create the object.
Also, the class you start with is the CoClass, in this case
class NetworkListManager(CoClassBaseClass): # A CoClass
is the one you want.
win32com.client.Dispatch('{DCB00C01-570F-4A9B-8D69-199FDBA5723B}')
works here.
Many of these Dispatch classes have a human readable dotted name as an alias, although
this particular one doesn't seem to.

Using Ladon in Python 2.6 on windows

I have been trying to create a web service out some python scripts, and haven't seemed to have had much luck. I am new to web services in general, but would really like to get this figured out. I'm on Windows 7 and use IIS7. The service also needs to be SOAP.
I've read through most posts that have anything to do with python and SOAP and tried out pretty much all the different libraries, but most of them just seem over my head (especially ZSI/SOAPpy). The Ladon Library seems like it would be best (and simplest) for what I need, but the tutorial http://www.youtube.com/watch?v=D_JYjEBedk4&feature=feedlik loses me at 5:10 when he brings it to the server. When I type the ladon2.6ctl in the cmd, it seems like windows gets quite confused. I'm guessing it is a little different because he is running on Linux and using Apache.
With that, any tips on how to get a python web service running on Microsoft 'stuff' would be greatly appreciated, as I have been trying to figure this stuff out for way too long.
One thing to note is the reason things are so specific (and seemingly strange) is because the scripts I have do a lot of geoprocessing with ESRI's "arcpy".
--Addition--
Traceback on localhost:8080/TestService:
Traceback (most recent call last):
<br>File "c:\Python26\ArcGIS10.0\lib\site-packages\ladon-0.5.1-py2.6.egg\ladon\server\wsgi_application.py", line 229, in __call__
exec("import %s" % ','.join(self.service_list))
File "<string>", line 1, in <module>
File "c:\Users\r\workspace\ladon\src\testspace.py", line 3, in <module>
class TestService2(object):
File "c:\Users\r\workspace\ladon\src\testspace.py", line 4, in TestService2
#ladonize(int,int,rtype=int)
File "c:\Python26\ArcGIS10.0\lib\site-packages\ladon-0.5.1-py2.6.egg\ladon\ladonizer\decorator.py", line 87, in decorator
ladon_method_info = global_service_collection().add_service_method(f,*def_args,**def_kw)
File "c:\Python26\ArcGIS10.0\lib\site-packages\ladon-0.5.1-py2.6.egg\ladon\ladonizer\collection.py", line 119, in add_service_method
sinfo = self.source_info(src_fname)
File "c:\Python26\ArcGIS10.0\lib\site-packages\ladon-0.5.1-py2.6.egg\ladon\ladonizer\collection.py", line 79, in source_info
a = ast.parse(src)
File "c:\Python26\ArcGIS10.0\lib\ast.py", line 37, in parse
return compile(expr, filename, mode, PyCF_ONLY_AST)
File "<unknown>", line 1
from ladon.ladonizer import ladonize
^
SyntaxError: invalid syntax
sample code:
from ladon.ladonizer import ladonize
class TestService2(object):
#ladonize(int,int,rtype=int)
def sum(self,a,b):
'''add two numbers<br>
param a: number 1
param b: number 2
rtype: sum of result
'''
return a+b

I must admit I normally use Linux for almost everything and I haven't tried Ladon on Windows for a while. I will spin up my windows installation later today and see if there is any trouble.
You wrote that ladon2.6ctl get's confused. Do you have an exception Traceback?

To summarize the fix for anyone else interested, delete the "syslog import" from these 3 ladon modules: ladon/interfaces/jsonwsp.py - line 6
ladon/dispatcher/dispatcher.py - line 7
ladon/server/wsgi_application.py - line 37
Then, you need to change the linefeed from window's default of /r/n to /n. In Eclipse, go to Window -> Preferences -> General, then select (not drop down) the Workspace tab. On the bottom right, select "other" under New text file line delimiter and change it to Unix.

Python RESTful client with CAS authentication

I'm trying to build a python library for interacting with our RESTful API, but it uses CAS for client auth, and I haven't been able to find any good existing libraries for it. So far I've found the following links, but I'm not sure if they're intended to be used in clients or by a website that uses CAS itself. Does anyone have any advice for a good library to use and a good way to structure my code for interacting with it?
https://wiki.jasig.org/download/attachments/28213515/pycas.py.txt
https://sp.princeton.edu/oit/sdp/CAS/Wiki%20Pages/Python.aspx
http://github.com/benoitc/restkit/
http://morethanseven.net/2009/02/18/python-rest-client.html
I also just tried using caslib, but that fails to work:
>>> import caslib
>>> srv = caslib.CASServer('https://my.cas/auth')
>>> svc = caslib.CASService('https://my.service/foo')
>>> caslib.login_to_cas_service(srv.login(svc),'user#example.com','password')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "caslib/cas_dance.py", line 250, in login_to_cas_service
raise CASLoginError('Could not parse the document at %s: %s' % (login_fh.url, errors))
caslib.cas_dance.CASLoginError: Could not parse the document at https://my.cas/auth/login?service=https%3A%2F%2Fmy.service%2Ffoo: undefined entity ©: line 97, column 26
Hmm, the error above appears to be in our markup (or the validater that caslib uses.)
Edit again: The failure is removed after installing the lxml library for python. The fallback parser didn't work as well.

You might have to roll you own solution, either by modifying the python rest client to support CAS, or building something from scratch (I would recommend on top of httplib2.)

Eleven years later, there are at least two Python CAS libraries, with Flask examples available:
python-cas - seems more current
Flask-CAS -- Github repo gone
I don't personally have these working yet, so YMMV.

Maybe, the official python example in: https://wiki.jasig.org/display/casum/restful+api