Lua

Get a Google Calendar OAuth2 Access Token

See more Google Calendar Examples

Demonstrates how to get a Google Calendar OAuth2 access token from a desktop application or script. Lua

local chilkat = require("chilkat")

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

local oauth2 = chilkat.OAuth2.new()

-- For Google OAuth2, set the listen port equal to the port used
-- in the Authorized Redirect URL for the Client ID.
-- For example, in this case the Authorized Redirect URL would be http://localhost:55568/
-- Your app should choose a port not likely not used by any other application.
oauth2.listen_port = 55568

oauth2.authorization_endpoint = "https://accounts.google.com/o/oauth2/v2/auth"
oauth2.token_endpoint = "https://www.googleapis.com/oauth2/v4/token"

-- Replace these with actual values.
oauth2.client_id = "GOOGLE-CLIENT-ID"
oauth2.client_secret = "GOOGLE-CLIENT-SECRET"

oauth2.code_challenge = true
oauth2.code_challenge_method = "S256"

-- These are the scopes for Google Calendar:
-- https://www.googleapis.com/auth/calendar     read/write access to Calendars
-- https://www.googleapis.com/auth/calendar.readonly     read-only access to Calendars
oauth2.scope = "https://www.googleapis.com/auth/calendar"

-- Begin the OAuth2 three-legged flow.  This returns a URL that should be loaded in a browser.
local url = oauth2:start_auth()
if not oauth2.last_method_success then
    print(oauth2.last_error_text)
    return
end

print(url)

-- Launch the system's default browser navigated to the URL.
local success = oauth2:launch_browser(url)
if not success then
    print(oauth2.last_error_text)
    return
end

-- Now wait for the authorization.
-- We'll wait for a max of 30 seconds.
local numMsWaited = 0
while (numMsWaited < 30000) and (oauth2.auth_flow_state < 3) do
    oauth2:sleep_ms(100)
    numMsWaited = numMsWaited + 100
end

-- If there was no response from the browser within 30 seconds, then
-- the AuthFlowState will be equal to 1 or 2.
-- 1: Waiting for Redirect. The OAuth2 background thread is waiting to receive the redirect HTTP request from the browser.
-- 2: Waiting for Final Response. The OAuth2 background thread is waiting for the final access token response.
-- In that case, cancel the background task started in the call to StartAuth.
if oauth2.auth_flow_state < 3 then
    oauth2:cancel()
    print("No response from the browser!")
    return
end

-- Check the AuthFlowState to see if authorization was granted, denied, or if some error occurred
-- The possible AuthFlowState values are:
-- 3: Completed with Success. The OAuth2 flow has completed, the background thread exited, and the successful JSON response is available in AccessTokenResponse property.
-- 4: Completed with Access Denied. The OAuth2 flow has completed, the background thread exited, and the error JSON is available in AccessTokenResponse property.
-- 5: Failed Prior to Completion. The OAuth2 flow failed to complete, the background thread exited, and the error information is available in the FailureInfo property.
if oauth2.auth_flow_state == 5 then
    print("OAuth2 failed to complete.")
    print(oauth2.failure_info)
    return
end

if oauth2.auth_flow_state == 4 then
    print("OAuth2 authorization was denied.")
    print(oauth2.access_token_response)
    return
end

if oauth2.auth_flow_state ~= 3 then
    print("Unexpected AuthFlowState:" .. oauth2.auth_flow_state)
    return
end

-- Save the full JSON access token response to a file.
local sbJson = chilkat.StringBuilder.new()
sbJson:append(oauth2.access_token_response)
sbJson:write_file("qa_data/tokens/googleCalendar.json", "utf-8", false)

-- The saved JSON response looks like this:

--     {
--      "access_token": "ya39.Ci-XA_C5bGgRDC3UaD-h0_NeL-DVIQnI2gHtBBBHkZzrwlARkwX6R3O0PCDEzRlfaQ",
--      "token_type": "Bearer",
--      "expires_in": 3600,
--      "refresh_token": "1/r_2c_7jddspcdfesrrfKqfXtqo08D6Q-gUU0DsdfVMsx0c"
--     }
--
print("OAuth2 authorization granted!")
print("Access Token = " .. oauth2.access_token)