Connectwise REST API Implementation using python - python-2.7

Question

In my application , I am going to use connectwise API , but I can't figure out how to call their API, like
How to connect
How to pass header (json data)
How to authentication (I have company id , public and private key)
How to make call and take response
I am Python guy
Thanks in advance

Answer 1

This question is quite broad, and you'll need to get familiar with something such as the Requests module if you aren't already.
Also, ConnectWise has a lot of documents at their developer site and registration is free and easy.
However I went through this journey myself over the last few weeks and learnt a lot so I'll share it with you.
Authentication
Authentication is done by creating an API user. In CW Manage you can create a member user with the API license class.
In ConnectWise Manage:
Go to System => Members
Go to the API Members tab.
Create a new API member that gives the API access to the areas that you need it, such as corporate/territorial levels. Note the username, amd that you cannot specify a password. Complete all the mandatory fields (owner ID, system default, group, approvers, etc).
When you have made this user go to the API keys tab. Enter a description for your new set of keys, and save it. When you do this you'll see the public and private keys once (and once only). Note them down.
Authorisation Header
In Python:
>>> import base64
>>> base64.b64encode("a+b:c")
...where a is your ConnectWise company name (what you type in in the login box), b is your public key, and c is your private key. This will return something which will be what you use to access the system. Copy it.
Making your first request
Now in Python make a new file and put this in it (this is quick and dirty but it should get you started):
import requests
cwToken = ""
# This is the ConnectWise access code generated earlier
cwUrl = "https://api-eu.myconnectwise.net/v4_6_release/apis/3.0/"
# check the URL matches your region, look at your CW Manage login box if not
cwHeaders = {"Authorization":"Basic " + cwToken,
"clientID":"<insertyoursecretClientIDhere>",
"Content-Type":"application/json"}
# this is your authorisation payload
try:
r = requests.get(cwUrl + "company/companies?pageSize=1000&conditions=type/id==1", headers=cwHeaders)
# request has been made
r.raise_for_status()
except:
print(r.text)
raise
companies = r.json()
The companies object now contains a list of your first 1,000 clients (type is ID 1 -- client). I've included an example of the conditions string because it took me a while to work out what it is and how to use it. But just take it off if you don't want the server to do your filtering for you.
You'll then be able to modify the above, or turn it into a module (which is what I did) to then make quick and portable calls, something like
cw.getCompanies()
which would simply return you a JSON object with all your companies in.
Going further
Study the documentation!! It is comprehensive enough to get you started. And the forums are actively monitored by staff (although they help mostly with C# queries and not scripting).

Answer 2

Just an update for 2020 since Daniel's response was incredibly helpful, but is missing a change Connectwise made in 2019 that now requires ClientIDs in order to auth.
Make a client ID here (scroll to bottom, although it's quick and useful to read all of it):
https://developer.connectwise.com/ClientID#What_is_a_clientId.3F
Daniel's code should then look like:
cwHeaders = {"Authorization":"Basic " + cwToken,
"clientID":"<insertyoursecretClientIDhere>",
"Content-Type":"application/json"}