Lua

Automatically Refresh Token for 401 Unauthorized

See more Google Calendar Examples

Demonstrates how to automatically refresh an access token (without user interaction) when the token expires and a 401 Unauthorized response is received. Lua

local chilkat = require("chilkat")

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

local tokenFilePath = "qa_data/tokens/googleCalendar.json"

-- Get our current access token.
local jsonToken = chilkat.JsonObject.new()
local success = jsonToken:load_file(tokenFilePath)
if not jsonToken:has_member("access_token") then
    print("No access token found.")
    return
end

local http = chilkat.Http.new()
http.auth_token = jsonToken:string_of("access_token")

local jsonResponse = http:quick_get_str("https://www.googleapis.com/calendar/v3/users/me/calendarList")
if not http.last_method_success then
    if http.last_status ~= 401 then
        print(http.last_error_text)
        print("----")
        print(http.last_response_body)
        return
    end

    -- The access token must've expired.
    -- Refresh the access token and then retry the request.
    local oauth2 = chilkat.OAuth2.new()

    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"

    -- Get the "refresh_token"
    oauth2.refresh_token = jsonToken:string_of("refresh_token")

    -- Send the HTTP POST to refresh the access token..
    success = oauth2:refresh_access_token()
    if not success then
        print(oauth2.last_error_text)
        return
    end

    -- The response contains a new access token, but we must keep
    -- our existing refresh token for when we need to refresh again in the future.
    jsonToken:update_string("access_token", oauth2.access_token)

    -- Save the new JSON access token response to a file.
    local sbJson = chilkat.StringBuilder.new()
    jsonToken.emit_compact = false
    jsonToken:emit_sb(sbJson)
    sbJson:write_file(tokenFilePath, "utf-8", false)

    print("OAuth2 authorization granted!")
    print("New Access Token = " .. oauth2.access_token)

    -- re-try the original request.
    http.auth_token = oauth2.access_token
    jsonResponse = http:quick_get_str("https://www.googleapis.com/calendar/v3/users/me/calendarList")
    if not http.last_method_success then
        print(http.last_error_text)
        return
    end
end

print(jsonResponse)
print("-----------------------------")