(PureBasic) 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 PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkJsonObject.pb"
IncludeFile "CkDateTime.pb"
IncludeFile "CkHttp.pb"
IncludeFile "CkFileAccess.pb"
IncludeFile "CkHttpRequest.pb"
IncludeFile "CkHttpResponse.pb"

Procedure ChilkatExample()

    ;  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.

    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success.i = CkJsonObject::ckLoadFile(json,"qa_data/tokens/dynamicsCrm.json")
    If success <> 1
        CkJsonObject::ckDispose(json)
        ProcedureReturn
    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.
    dtExpire.i = CkDateTime::ckCreate()
    If dtExpire.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkDateTime::ckSetFromUnixTime(dtExpire,0,CkJsonObject::ckIntOf(json,"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...
    ; 

    req.i = CkHttpRequest::ckCreate()
    If req.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkHttpRequest::ckAddParam(req,"grant_type","refresh_token")
    CkHttpRequest::ckAddParam(req,"redirect_uri","http://localhost:3017/")
    CkHttpRequest::ckAddParam(req,"client_id","DYNAMICS-CRM-CLIENT-ID")
    CkHttpRequest::ckAddParam(req,"client_secret","DYNAMICS-CRM-SECRET-KEY")
    CkHttpRequest::ckAddParam(req,"refresh_token",CkJsonObject::ckStringOf(json,"refresh_token"))
    CkHttpRequest::ckAddParam(req,"resource","https://mydynamicsdomain.api.crm.dynamics.com")

    http.i = CkHttp::ckCreate()
    If http.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    resp.i = CkHttp::ckPostUrlEncoded(http,"https://login.microsoftonline.com/DYNAMICS-ENDPOINT-GUID/oauth2/token",req)
    If CkHttp::ckLastMethodSuccess(http) <> 1
        Debug CkHttp::ckLastErrorText(http)
        CkJsonObject::ckDispose(json)
        CkDateTime::ckDispose(dtExpire)
        CkHttpRequest::ckDispose(req)
        CkHttp::ckDispose(http)
        ProcedureReturn
    EndIf

    ;  Load the JSON response.
    CkJsonObject::ckLoad(json,CkHttpResponse::ckBodyStr(resp))
    CkJsonObject::setCkEmitCompact(json, 0)

    ;  Show the JSON response.
    Debug CkJsonObject::ckEmit(json)

    Debug "Response status code: " + Str(CkHttpResponse::ckStatusCode(resp))

    ;  If the response status code is not 200, then it's an error.
    If CkHttpResponse::ckStatusCode(resp) <> 200
        CkJsonObject::ckDispose(json)
        CkDateTime::ckDispose(dtExpire)
        CkHttpRequest::ckDispose(req)
        CkHttp::ckDispose(http)
        ProcedureReturn
    EndIf

    CkHttpResponse::ckDispose(resp)

    ;  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 CkJsonObject::ckHasMember(json,"expires_on") <> 1
        CkDateTime::ckSetFromCurrentSystemTime(dtExpire)
        CkDateTime::ckAddSeconds(dtExpire,CkJsonObject::ckIntOf(json,"expires_in"))
        CkJsonObject::ckAppendString(json,"expires_on",CkDateTime::ckGetAsUnixTimeStr(dtExpire,0))
    EndIf

    ;  Save the refreshed access token JSON to a file for future requests.
    fac.i = CkFileAccess::ckCreate()
    If fac.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkFileAccess::ckWriteEntireTextFile(fac,"qa_data/tokens/dynamicsCrm.json",CkJsonObject::ckEmit(json),"utf-8",0)


    CkJsonObject::ckDispose(json)
    CkDateTime::ckDispose(dtExpire)
    CkHttpRequest::ckDispose(req)
    CkHttp::ckDispose(http)
    CkFileAccess::ckDispose(fac)


    ProcedureReturn
EndProcedure