Xbase++ Requires Chilkat v10.1.2+

Facebook OAuth2 Access Token

See more Facebook Examples

Demonstrates how to get a Facebook OAuth2 access token from a desktop application or script. Xbase++

LOCAL nSuccess
LOCAL oOauth2
LOCAL cUrl
LOCAL nNumMsWaited

nSuccess := 0

//  To further clarify, see OAuth 2.0 Authorization Flow

oOauth2 := CreateObject("Chilkat.OAuth2")

//  This should match the Site URL configured for your Facebook APP, such as "http://localhost:3017/"
oOauth2:ListenPort := 3017

oOauth2:AuthorizationEndpoint := "https://www.facebook.com/dialog/oauth"
oOauth2:TokenEndpoint := "https://graph.facebook.com/oauth/access_token"

//  Replace this with your actual App ID
oOauth2:ClientId := "APP_ID"

//  Set the Scope to a comma-separated list of permissions the app wishes to request.
//  See https://developers.facebook.com/docs/facebook-login/permissions/ for a full list of permissions.
oOauth2:Scope := "public_profile,user_friends,email,user_posts,user_likes,user_photos"

//  This is for Require Proof Key for Code Exchange (PKCE)
//  See OAuth2 PKCE Explained
oOauth2:CodeChallenge := 1
oOauth2:CodeChallengeMethod := "S256"

//  Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
cUrl := oOauth2:StartAuth()
IF (oOauth2:LastMethodSuccess != 1)
    ? oOauth2:LastErrorText
    oOauth2:destroy()
    RETURN
ENDIF

? "url = " + cUrl

//  Launch the default browser on the system and navigate to the url.
//  The LaunchBrowser method was added in Chilkat v10.1.2.
nSuccess := oOauth2:LaunchBrowser(cUrl)
IF (nSuccess == 0)
    ? oOauth2:LastErrorText
    oOauth2:destroy()
    RETURN
ENDIF

//  Wait for the user to approve or deny authorization in the browser.
nNumMsWaited := 0
DO WHILE (nNumMsWaited < 90000) .AND. (oOauth2:AuthFlowState < 3)
    oOauth2:SleepMs(100)
    nNumMsWaited := nNumMsWaited + 100
ENDDO

//  If the browser does not respond within the specified time, AuthFlowState will be:
//  
//  1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
//  2: Waiting for Final Response – The thread is awaiting the final access token response.
//  In either case, cancel the background task initiated by StartAuth.

IF (oOauth2:AuthFlowState < 3)
    oOauth2:Cancel()
    ? "No response from the browser!"
    oOauth2:destroy()
    RETURN
ENDIF

//  Check AuthFlowState to determine if authorization was granted, denied, or failed:
//  
//  3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
//  4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
//  5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

IF (oOauth2:AuthFlowState == 5)
    ? "OAuth2 failed to complete."
    ? oOauth2:FailureInfo
    oOauth2:destroy()
    RETURN
ENDIF

IF (oOauth2:AuthFlowState == 4)
    ? "OAuth2 authorization was denied."
    ? oOauth2:AccessTokenResponse
    oOauth2:destroy()
    RETURN
ENDIF

IF (oOauth2:AuthFlowState != 3)
    ? "Unexpected AuthFlowState:" + Str(oOauth2:AuthFlowState)
    oOauth2:destroy()
    RETURN
ENDIF

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

oOauth2:destroy()