(Go) 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.)

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    // 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 := chilkat.NewJsonObject()
    success := json.LoadFile("qa_data/tokens/dynamicsCrm.json")
    if success != true {
        json.DisposeJsonObject()
        return
    }

    // 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 := chilkat.NewCkDateTime()
    dtExpire.SetFromUnixTime(false,*json.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...
    // 

    req := chilkat.NewHttpRequest()
    req.AddParam("grant_type","refresh_token")
    req.AddParam("redirect_uri","http://localhost:3017/")
    req.AddParam("client_id","DYNAMICS-CRM-CLIENT-ID")
    req.AddParam("client_secret","DYNAMICS-CRM-SECRET-KEY")
    req.AddParam("refresh_token",*json.StringOf("refresh_token"))
    req.AddParam("resource","https://mydynamicsdomain.api.crm.dynamics.com")

    http := chilkat.NewHttp()

    resp := http.PostUrlEncoded("https://login.microsoftonline.com/DYNAMICS-ENDPOINT-GUID/oauth2/token",req)
    if http.LastMethodSuccess() != true {
        fmt.Println(http.LastErrorText())
        json.DisposeJsonObject()
        dtExpire.DisposeCkDateTime()
        req.DisposeHttpRequest()
        http.DisposeHttp()
        return
    }

    // Load the JSON response.
    json.Load(resp.BodyStr())
    json.SetEmitCompact(false)

    // Show the JSON response.
    fmt.Println(*json.Emit())

    fmt.Println("Response status code: ", resp.StatusCode())

    // If the response status code is not 200, then it's an error.
    if resp.StatusCode() != 200 {
        json.DisposeJsonObject()
        dtExpire.DisposeCkDateTime()
        req.DisposeHttpRequest()
        http.DisposeHttp()
        return
    }

    resp.DisposeHttpResponse()

    // 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 json.HasMember("expires_on") != true {
        dtExpire.SetFromCurrentSystemTime()
        dtExpire.AddSeconds(*json.IntOf("expires_in"))
        json.AppendString("expires_on",*dtExpire.GetAsUnixTimeStr(false))
    }

    // Save the refreshed access token JSON to a file for future requests.
    fac := chilkat.NewFileAccess()
    fac.WriteEntireTextFile("qa_data/tokens/dynamicsCrm.json",*json.Emit(),"utf-8",false)

    json.DisposeJsonObject()
    dtExpire.DisposeCkDateTime()
    req.DisposeHttpRequest()
    http.DisposeHttp()
    fac.DisposeFileAccess()