(Visual FoxPro) Refresh a Dynamics CRM OAuth2 Access Token

Demonstrates how to refresh an expiring Dynamics CRM access token using the refresh token. endpoint.

(If a REST API call fails with a 401 unauthorized error, an application can auto-recover by refreshing the access token, and then re-send the request using the new token.)

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loJson
LOCAL lnSuccess
LOCAL loDtExpire
LOCAL loReq
LOCAL loHttp
LOCAL loResp
LOCAL loFac

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

* We previously obtained an access token and saved the JSON to a file using this example:
* Get Dynamics CRM OAuth2 Access Token

* This example will examine the JSON and expiration date, and if near expiration will
* refresh the access token.

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJson = CreateObject('Chilkat.JsonObject')
lnSuccess = loJson.LoadFile("qa_data/tokens/dynamicsCrm.json")
IF (lnSuccess <> 1) THEN
    RELEASE loJson
    CANCEL
ENDIF

* The contents of the JSON look 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": "..."
* }

* The "expires_on" value is a Unix time.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.CkDateTime')
loDtExpire = CreateObject('Chilkat.CkDateTime')
loDtExpire.SetFromUnixTime(0,loJson.IntOf("expires_on"))

* If this date/time expires within 10 minutes of the current system time, refresh the token.

* OK, we need to refresh the access token by sending a POST...
* 

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.HttpRequest')
loReq = CreateObject('Chilkat.HttpRequest')
loReq.AddParam("grant_type","refresh_token")
loReq.AddParam("redirect_uri","http://localhost:3017/")
loReq.AddParam("client_id","DYNAMICS-CRM-CLIENT-ID")
loReq.AddParam("client_secret","DYNAMICS-CRM-SECRET-KEY")
loReq.AddParam("refresh_token",loJson.StringOf("refresh_token"))
loReq.AddParam("resource","https://mydynamicsdomain.api.crm.dynamics.com")

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Http')
loHttp = CreateObject('Chilkat.Http')

loResp = loHttp.PostUrlEncoded("https://login.microsoftonline.com/DYNAMICS-ENDPOINT-GUID/oauth2/token",loReq)
IF (loHttp.LastMethodSuccess <> 1) THEN
    ? loHttp.LastErrorText
    RELEASE loJson
    RELEASE loDtExpire
    RELEASE loReq
    RELEASE loHttp
    CANCEL
ENDIF

* Load the JSON response.
loJson.Load(loResp.BodyStr)
loJson.EmitCompact = 0

* Show the JSON response.
? loJson.Emit()

? "Response status code: " + STR(loResp.StatusCode)

* If the response status code is not 200, then it's an error.
IF (loResp.StatusCode <> 200) THEN
    RELEASE loJson
    RELEASE loDtExpire
    RELEASE loReq
    RELEASE loHttp
    CANCEL
ENDIF

RELEASE loResp

* 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 (loJson.HasMember("expires_on") <> 1) THEN
    loDtExpire.SetFromCurrentSystemTime()
    loDtExpire.AddSeconds(loJson.IntOf("expires_in"))
    loJson.AppendString("expires_on",loDtExpire.GetAsUnixTimeStr(0))
ENDIF

* Save the refreshed access token JSON to a file for future requests.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.FileAccess')
loFac = CreateObject('Chilkat.FileAccess')
loFac.WriteEntireTextFile("qa_data/tokens/dynamicsCrm.json",loJson.Emit(),"utf-8",0)

RELEASE loJson
RELEASE loDtExpire
RELEASE loReq
RELEASE loHttp
RELEASE loFac