Lua

Refresh HMRC OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to refresh an HMRC access token. Lua

local chilkat = require("chilkat")

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

-- See Get HMRC Access Token
-- for sample code showing how to obtain a HMRC access token for desktop apps.

-- It is assumed we previously obtained an OAuth2 access token for HMRC.

local jsonToken = chilkat.JsonObject.new()
local success = jsonToken:load_file("qa_data/tokens/hmrc.json")
if not success then
    print("Failed to load hmrc.json")
    return
end

-- The access token JSON looks something 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": "..."
-- }

local oauth2 = chilkat.OAuth2.new()

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

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

-- Load the access token response into the json object
jsonToken:load(oauth2.access_token_response)

-- 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 jsonToken:has_member("expires_on") then
    local dtExpire = chilkat.DateTime.new()
    dtExpire:set_from_current_system_time()
    dtExpire:add_seconds(jsonToken:int_of("expires_in"))
    jsonToken:append_string("expires_on", dtExpire:get_as_unix_time_str(false))
end

-- 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.
local sbJson = chilkat.StringBuilder.new()
jsonToken.emit_compact = false
jsonToken:emit_sb(sbJson)
sbJson:write_file("qa_data/tokens/hmrc.json", "utf-8", false)

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