(Visual FoxPro) Dropbox: OAuth2 Authorization to Obtain an Access Token

See more Dropbox Examples

This example runs the OAuth 2.0 authorization flow that lets the user sign in to Dropbox and authorize your app.

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

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

LOCAL loOauth2
LOCAL lcUrl
LOCAL lnSuccess
LOCAL lnNumMsWaited
LOCAL loJson

* For more information about the OAuth2, see OAuth 2.0 Authorization Flow

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.OAuth2')
loOauth2 = CreateObject('Chilkat.OAuth2')

* The port should match the Authorized Redirect URL in your Dropbox app, 
* which would look like "http://localhost:3017/"
loOauth2.ListenPort = 3017

* IMPORTANT: One of the OAuth2 redirect URIs for your Dropbox app must be
* exactly this string:  http://localhost:3017/

loOauth2.AuthorizationEndpoint = "https://www.dropbox.com/oauth2/authorize"
loOauth2.TokenEndpoint = "https://api.dropboxapi.com/oauth2/token"

* Replace this with your actual Dropbox App Key
loOauth2.ClientId = "DROPBOX_APP_KEY"

* This is for Require Proof Key for Code Exchange (PKCE)
* See OAuth2 PKCE Explained
loOauth2.CodeChallenge = 1
loOauth2.CodeChallengeMethod = "S256"

* Add token_access_type=offline to also get a refresh token in the response
loOauth2.AddAuthQueryParam("token_access_type","offline")

* Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
lcUrl = loOauth2.StartAuth()
IF (loOauth2.LastMethodSuccess <> 1) THEN
    ? loOauth2.LastErrorText
    RELEASE loOauth2
    CANCEL
ENDIF

? "url = " + lcUrl

* Launch the default browser on the system and navigate to the url.
* The LaunchBrowser method was added in Chilkat v10.1.2.
lnSuccess = loOauth2.LaunchBrowser(lcUrl)
IF (lnSuccess = 0) THEN
    ? loOauth2.LastErrorText
    RELEASE loOauth2
    CANCEL
ENDIF

* Wait for the user to approve or deny authorization in the browser.
lnNumMsWaited = 0
DO WHILE (lnNumMsWaited < 90000) AND (loOauth2.AuthFlowState < 3)
    loOauth2.SleepMs(100)
    lnNumMsWaited = lnNumMsWaited + 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 (loOauth2.AuthFlowState < 3) THEN
    loOauth2.Cancel()
    ? "No response from the browser!"
    RELEASE loOauth2
    CANCEL
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 (loOauth2.AuthFlowState = 5) THEN
    ? "OAuth2 failed to complete."
    ? loOauth2.FailureInfo
    RELEASE loOauth2
    CANCEL
ENDIF

IF (loOauth2.AuthFlowState = 4) THEN
    ? "OAuth2 authorization was denied."
    ? loOauth2.AccessTokenResponse
    RELEASE loOauth2
    CANCEL
ENDIF

IF (loOauth2.AuthFlowState <> 3) THEN
    ? "Unexpected AuthFlowState:" + STR(loOauth2.AuthFlowState)
    RELEASE loOauth2
    CANCEL
ENDIF

? "OAuth2 authorization granted!"

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJson = CreateObject('Chilkat.JsonObject')
loJson.Load(loOauth2.AccessTokenResponse)
loJson.EmitCompact = 0

? "Access Token Response = " + loJson.Emit()

* A sample access token response:

* {
*   "access_token": "...",
*   "token_type": "bearer",
*   "expires_in": 14399,
*   "refresh_token": "...",
*   "scope": "account_info.read",
*   "uid": "562542581",
*   "account_id": "dbid:AACQhDS0E3_Vb72Ynd0F-GxGWdTI2qcTHzA"
* }

? "Access Token = " + loOauth2.AccessToken

* Save the JSON access token response to a file for subsequent use..
loJson.WriteFile("qa_data/tokens/dropbox.json")

RELEASE loOauth2
RELEASE loJson