Lua Requires Chilkat v10.1.2+

HMRC OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to get an HMRC OAuth2 access token from a desktop (installed) application or script. This example gets an HMRC MTD VAT read/write access token. Lua

local chilkat = require("chilkat")

-- To further clarify, see OAuth 2.0 Authorization Flow

local oauth2 = chilkat.OAuth2.new()

-- This should be the port in the localhost callback URL for your app.
-- Important: Make sure the callback URI in your HMRC developer app
-- is exactly "http://localhost:3017/".  Don't forget the ending "/" char.
-- The callback URL would look like "http://localhost:3017/" if the port number is 3017.

-- IMPORTANT: Don't forget to setup your HMRC application to use the Redirect URI "http://localhost:3017/" as shown
-- here: Configure Redirect URI for HMRC application
oauth2.listen_port = 3017

oauth2.authorization_endpoint = "https://test-api.service.hmrc.gov.uk/oauth/authorize"
oauth2.token_endpoint = "https://test-api.service.hmrc.gov.uk/oauth/token"

-- Replace with your actual client ID
oauth2.client_id = "HMRC-CLIENT-ID"

-- The scopes are documented in the HMRC reference documentation for each API.
-- This example gets a read/write access token for the HMRC MTD VAT API.
oauth2.scope = "read:vat write:vat"

-- Begin the OAuth2 Authorization code 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

-- Launch the default browser on the system and navigate to the url.
local success = oauth2:launch_browser(url)
if not success then
    print(oauth2.last_error_text)
    return
end

-- Wait for the user to approve or deny authorization in the browser.
local numMsWaited = 0
while (numMsWaited < 90000) and (oauth2.auth_flow_state < 3) do
    oauth2:sleep_ms(100)
    numMsWaited = numMsWaited + 100
end

-- If the browser does not respond within the specified time, AuthFlowState will be:
--
-- 1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
-- 2: Waiting for Final Response – The thread is awaiting the final access token response.
-- In either case, cancel the background task initiated by StartAuth.

if oauth2.auth_flow_state < 3 then
    oauth2:cancel()
    print("No response from the browser!")
    return
end

-- Check AuthFlowState to determine if authorization was granted, denied, or failed:
--
-- 3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
-- 4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
-- 5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

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

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

-- Get the full JSON response:
local json = chilkat.JsonObject.new()
json:load(oauth2.access_token_response)
json.emit_compact = false
print(json:emit())

-- The JSON response looks like this:

-- {
--   "token_type": "Bearer",
--   "scope": "user_impersonation",
--   "expires_in": "3599",
--   "ext_expires_in": "0",
--   "expires_on": "1524783438",
--   "not_before": "1524779538",
--   "resource": "https://mydomain.api.crm.dynamics.com",
--   "access_token": "...",
--   "refresh_token": "...",
--   "id_token": "..."
-- }

-- If an "expires_on" member does not exist, then add the JSON member by
-- getting the current system date/time and adding the "expires_in" seconds.
-- This way we'll know when the token expires.
if not json:has_member("expires_on") then
    local dtExpire = chilkat.DateTime.new()
    dtExpire:set_from_current_system_time()
    dtExpire:add_seconds(json:int_of("expires_in"))
    json:append_string("expires_on", dtExpire:get_as_unix_time_str(false))
end

print(json:emit())

-- Save the JSON to a file for future requests.
local fac = chilkat.FileAccess.new()
fac:write_entire_text_file("qa_data/tokens/hmrc.json", json:emit(), "utf-8", false)