Xbase++

Refresh HMRC OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to refresh an HMRC access token. Xbase++

LOCAL nSuccess
LOCAL oJsonToken
LOCAL oOauth2
LOCAL oDtExpire
LOCAL oSbJson

nSuccess := 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.

oJsonToken := CreateObject("Chilkat.JsonObject")
nSuccess := oJsonToken:LoadFile("qa_data/tokens/hmrc.json")
IF (nSuccess != 1)
    ? "Failed to load hmrc.json"
    oJsonToken:destroy()
    RETURN
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": "..."
//  }

oOauth2 := CreateObject("Chilkat.OAuth2")

oOauth2:TokenEndpoint := "https://test-api.service.hmrc.gov.uk/oauth/token"

//  Replace these with actual values.
oOauth2:ClientId := "HMRC-CLIENT-ID"
oOauth2:ClientSecret := "HMRC-CLIENT-SECRET"

//  Get the "refresh_token"
oOauth2:RefreshToken := oJsonToken:StringOf("refresh_token")

//  Send the HTTP POST to refresh the access token..
nSuccess := oOauth2:RefreshAccessToken()
IF (nSuccess != 1)
    ? oOauth2:LastErrorText
    oJsonToken:destroy()
    oOauth2:destroy()
    RETURN
ENDIF

//  Load the access token response into the json object 
oJsonToken:Load(oOauth2: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 (oJsonToken:HasMember("expires_on") == 0)
    oDtExpire := CreateObject("Chilkat.CkDateTime")
    oDtExpire:SetFromCurrentSystemTime()
    oDtExpire:AddSeconds(oJsonToken:IntOf("expires_in"))
    oJsonToken:AppendString("expires_on", oDtExpire: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.
oSbJson := CreateObject("Chilkat.StringBuilder")
oJsonToken:EmitCompact := 0
oJsonToken:EmitSb(oSbJson)
oSbJson:WriteFile("qa_data/tokens/hmrc.json", "utf-8", 0)

? "OAuth2 authorization granted!"
? "New Access Token = " + oOauth2:AccessToken

oJsonToken:destroy()
oOauth2:destroy()
oDtExpire:destroy()
oSbJson:destroy()