Visual FoxPro

Refresh HMRC OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to refresh an HMRC access token. Visual FoxPro

LOCAL lnSuccess
LOCAL loJsonToken
LOCAL loOauth2
LOCAL loDtExpire
LOCAL loSbJson

lnSuccess = 0

* 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.

loJsonToken = CreateObject('Chilkat.JsonObject')
lnSuccess = loJsonToken.LoadFile("qa_data/tokens/hmrc.json")
IF (lnSuccess <> 1) THEN
    ? "Failed to load hmrc.json"
    RELEASE loJsonToken
    CANCEL
ENDIF

* 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": "..."
* }

loOauth2 = CreateObject('Chilkat.OAuth2')

loOauth2.TokenEndpoint = "https://test-api.service.hmrc.gov.uk/oauth/token"

* Replace these with actual values.
loOauth2.ClientId = "HMRC-CLIENT-ID"
loOauth2.ClientSecret = "HMRC-CLIENT-SECRET"

* Get the "refresh_token"
loOauth2.RefreshToken = loJsonToken.StringOf("refresh_token")

* Send the HTTP POST to refresh the access token..
lnSuccess = loOauth2.RefreshAccessToken()
IF (lnSuccess <> 1) THEN
    ? loOauth2.LastErrorText
    RELEASE loJsonToken
    RELEASE loOauth2
    CANCEL
ENDIF

* Load the access token response into the json object 
loJsonToken.Load(loOauth2.AccessTokenResponse)

* 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 (loJsonToken.HasMember("expires_on") = 0) THEN
    loDtExpire = CreateObject('Chilkat.CkDateTime')
    loDtExpire.SetFromCurrentSystemTime()
    loDtExpire.AddSeconds(loJsonToken.IntOf("expires_in"))
    loJsonToken.AppendString("expires_on",loDtExpire.GetAsUnixTimeStr(0))
ENDIF

* 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.
loSbJson = CreateObject('Chilkat.StringBuilder')
loJsonToken.EmitCompact = 0
loJsonToken.EmitSb(loSbJson)
loSbJson.WriteFile("qa_data/tokens/hmrc.json","utf-8",0)

? "OAuth2 authorization granted!"
? "New Access Token = " + loOauth2.AccessToken

RELEASE loJsonToken
RELEASE loOauth2
RELEASE loDtExpire
RELEASE loSbJson