CkPython Requires Chilkat v11.0.0+
QuickBooks - Automatically Refresh Access Token with No User Interaction

Demonstrates how to automaticaly refresh an expired access token and retry the request after a 401 authorization error.
Chilkat CkPython Downloads

CkPython
import sys
import chilkat

success = False

#  This example assumes the Chilkat API to have been previously unlocked.
#  See Global Unlock Sample for sample code.

#  Get our previously obtained OAuth2 access token, which should contain JSON like this:
#  {
#    "expires_in": 3600,
#    "x_refresh_token_expires_in": 8726400,
#    "refresh_token": "L011546037639r ... 3vR2DrbOmg0Sdagw",
#    "access_token": "eyJlbmMiOiJBMTI4Q0 ... oETJEMbeggg",
#    "token_type": "bearer"
#  }

jsonToken = chilkat.CkJsonObject()
success = jsonToken.LoadFile("qa_data/tokens/qb-access-token.json")

rest = chilkat.CkRest()

#  Connect using TLS.
#  A single REST object, once connected, can be used for many Quickbooks REST API calls.
#  The auto-reconnect indicates that if the already-established HTTPS connection is closed,
#  then it will be automatically re-established as needed.
bAutoReconnect = True
success = rest.Connect("sandbox-quickbooks.api.intuit.com",443,True,bAutoReconnect)
if (success == False):
    print(rest.lastErrorText())
    sys.exit()

sbAuth = chilkat.CkStringBuilder()
sbAuth.Append("Bearer ")
sbAuth.Append(jsonToken.stringOf("access_token"))
rest.put_Authorization(sbAuth.getAsString())

rest.AddHeader("Accept","application/json")
rest.put_AllowHeaderFolding(False)

#  The company ID is 123146096291789
#  The employee ID is 58
responseBody = rest.fullRequestNoBody("GET","/v3/company/123146096291789/employee/58?minorversion=45")
if (rest.get_LastMethodSuccess() == False):
    print(rest.lastErrorText())
    sys.exit()

#  If we get a 401 authorization error, then it's likely because the access token expired.
#  We can automatically refresh it without interaction from the user.
if (rest.get_ResponseStatusCode() == 401):

    oauth2 = chilkat.CkOAuth2()

    oauth2.put_TokenEndpoint("https://oauth.platform.intuit.com/oauth2/v1/tokens/bearer")

    #  Replace these with actual values.
    oauth2.put_ClientId("QUICKBOOKS-CLIENT-ID")
    oauth2.put_ClientSecret("QUICKBOOKS-CLIENT-SECRET")

    #  Get the "refresh_token"
    oauth2.put_RefreshToken(jsonToken.stringOf("refresh_token"))

    #  Send the HTTP POST to refresh the access token..
    success = oauth2.RefreshAccessToken()
    if (success == False):
        print(oauth2.lastErrorText())
        sys.exit()

    print("New access token: " + oauth2.accessToken())

    #  Update the JSON with the new tokens.
    jsonToken.UpdateString("access_token",oauth2.accessToken())

    #  Save the new JSON access token response to a file.
    #  The access + refresh tokens contained in this JSON will be needed for the next refresh.
    sbJson = chilkat.CkStringBuilder()
    jsonToken.put_EmitCompact(False)
    jsonToken.EmitSb(sbJson)
    sbJson.WriteFile("qa_data/tokens/qb-access-token.json","utf-8",False)

    print("OAuth2 token refreshed!")
    print("New Access Token = " + oauth2.accessToken())

    sbAuth.Clear()
    sbAuth.Append("Bearer ")
    sbAuth.Append(oauth2.accessToken())
    rest.put_Authorization(sbAuth.getAsString())

    #  Now retry the request with the refreshed access token...
    responseBody = rest.fullRequestNoBody("GET","/v3/company/123146096291789/employee/58?minorversion=45")
    if (rest.get_LastMethodSuccess() == False):
        print(rest.lastErrorText())
        sys.exit()

#  We should expect a 200 response if successful.
if (rest.get_ResponseStatusCode() != 200):
    print("Request Header: ")
    print(rest.lastRequestHeader())
    print("----")
    print("Response StatusCode = " + str(rest.get_ResponseStatusCode()))
    print("Response StatusLine: " + rest.responseStatusText())
    print("Response Header:")
    print(rest.responseHeader())
    print(responseBody)
    sys.exit()

#  Load the JSON response into a JSON object for parsing.
#  A sample JSON response is shown below.
json = chilkat.CkJsonObject()
json.Load(responseBody)

#  These will be used for parsing date/time strings..
dtime = chilkat.CkDateTime()
bLocalTime = True

#  Show the JSON.   
json.put_EmitCompact(False)
print(json.emit())

#  Get some information from the JSON..
print("Name: " + json.stringOf("Employee.DisplayName"))
print("Id: " + json.stringOf("Employee.Id"))
print("City: " + json.stringOf("Employee.PrimaryAddr.City"))
print("PostalCode: " + json.stringOf("Employee.PrimaryAddr.PostalCode"))

#  Load the CreateTime into a CkDateTime...
dtime.SetFromTimestamp(json.stringOf("Employee.MetaData.CreateTime"))
dt = chilkat.CkDtObj()
dtime.ToDtObj(bLocalTime,dt)

print(str(dt.get_Month()) + "/" + str(dt.get_Day()) + "/" + str(dt.get_Year()) + "  " + str(dt.get_Hour()) + ":" + str(dt.get_Minute()))

print("Success.")

#  Use this online tool to generate parsing code from sample JSON: 
#  Generate Parsing Code from JSON

#  ------------------------------------------------------
#  The JSON response looks like this:

#  {
#    "Employee": {
#      "SSN": "XXX-XX-XXXX",
#      "PrimaryAddr": {
#        "Id": "116",
#        "Line1": "45 N. Elm Street",
#        "City": "Middlefield",
#        "CountrySubDivisionCode": "CA",
#        "PostalCode": "93242"
#      },
#      "BillableTime": false,
#      "domain": "QBO",
#      "sparse": false,
#      "Id": "98",
#      "SyncToken": "0",
#      "MetaData": {
#        "CreateTime": "2015-07-24T09:34:35-07:00",
#        "LastUpdatedTime": "2015-07-24T09:34:35-07:00"
#      },
#      "GivenName": "Bill",
#      "FamilyName": "Miller",
#      "DisplayName": "Bill Miller",
#      "PrintOnCheckName": "Bill Miller",
#      "Active": true,
#      "PrimaryPhone": {
#        "FreeFormNumber": "234-525-1234"
#      }
#    },
#    "time": "2015-07-24T09:35:54.805-07:00"
#  }