(Visual Basic 6.0) Facebook OAuth2 Access Token

See more Facebook Examples

Note: This example requires Chilkat v10.1.2 or greater.

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

' To further clarify, see OAuth 2.0 Authorization Flow

Dim oauth2 As New ChilkatOAuth2

' This should match the Site URL configured for your Facebook APP, such as "http://localhost:3017/"
oauth2.ListenPort = 3017

oauth2.AuthorizationEndpoint = "https://www.facebook.com/dialog/oauth"
oauth2.TokenEndpoint = "https://graph.facebook.com/oauth/access_token"

' Replace this with your actual App ID
oauth2.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.
oauth2.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
oauth2.CodeChallenge = 1
oauth2.CodeChallengeMethod = "S256"

' Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
Dim url As String
url = oauth2.StartAuth()
If (oauth2.LastMethodSuccess <> 1) Then
    Debug.Print oauth2.LastErrorText
    Exit Sub
End If

Debug.Print "url = " & url

' Launch the default browser on the system and navigate to the url.
' The LaunchBrowser method was added in Chilkat v10.1.2.
Dim success As Long
success = oauth2.LaunchBrowser(url)
If (success = 0) Then
    Debug.Print oauth2.LastErrorText
    Exit Sub
End If

' Wait for the user to approve or deny authorization in the browser.
Dim numMsWaited As Long
numMsWaited = 0
Do While (numMsWaited < 90000) And (oauth2.AuthFlowState < 3)
    oauth2.SleepMs 100
    numMsWaited = numMsWaited + 100
Loop

' 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 (oauth2.AuthFlowState < 3) Then
    success = oauth2.Cancel()
    Debug.Print "No response from the browser!"
    Exit Sub
End If

' 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 (oauth2.AuthFlowState = 5) Then
    Debug.Print "OAuth2 failed to complete."
    Debug.Print oauth2.FailureInfo
    Exit Sub
End If

If (oauth2.AuthFlowState = 4) Then
    Debug.Print "OAuth2 authorization was denied."
    Debug.Print oauth2.AccessTokenResponse
    Exit Sub
End If

If (oauth2.AuthFlowState <> 3) Then
    Debug.Print "Unexpected AuthFlowState:" & oauth2.AuthFlowState
    Exit Sub
End If

Debug.Print "OAuth2 authorization granted!"
Debug.Print "Access Token = " & oauth2.AccessToken