(PureBasic) 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 PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkOAuth2.pb"
IncludeFile "CkJsonObject.pb"

Procedure ChilkatExample()

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

    oauth2.i = CkOAuth2::ckCreate()
    If oauth2.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; The port should match the Authorized Redirect URL in your Dropbox app, 
    ; which would look like "http://localhost:3017/"
    CkOAuth2::setCkListenPort(oauth2, 3017)

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

    CkOAuth2::setCkAuthorizationEndpoint(oauth2, "https://www.dropbox.com/oauth2/authorize")
    CkOAuth2::setCkTokenEndpoint(oauth2, "https://api.dropboxapi.com/oauth2/token")

    ; Replace this with your actual Dropbox App Key
    CkOAuth2::setCkClientId(oauth2, "DROPBOX_APP_KEY")

    ; This is for Require Proof Key for Code Exchange (PKCE)
    ; See OAuth2 PKCE Explained
    CkOAuth2::setCkCodeChallenge(oauth2, 1)
    CkOAuth2::setCkCodeChallengeMethod(oauth2, "S256")

    ; Add token_access_type=offline to also get a refresh token in the response
    CkOAuth2::ckAddAuthQueryParam(oauth2,"token_access_type","offline")

    ; Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
    url.s = CkOAuth2::ckStartAuth(oauth2)
    If CkOAuth2::ckLastMethodSuccess(oauth2) <> 1
        Debug CkOAuth2::ckLastErrorText(oauth2)
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    Debug "url = " + url

    ; Launch the default browser on the system and navigate to the url.
    ; The LaunchBrowser method was added in Chilkat v10.1.2.
    success.i = CkOAuth2::ckLaunchBrowser(oauth2,url)
    If success = 0
        Debug CkOAuth2::ckLastErrorText(oauth2)
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    ; Wait for the user to approve or deny authorization in the browser.
    numMsWaited.i = 0
    While (numMsWaited < 90000) AND (CkOAuth2::ckAuthFlowState(oauth2) < 3)
        CkOAuth2::ckSleepMs(oauth2,100)
        numMsWaited = numMsWaited + 100
    Wend

    ; 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 CkOAuth2::ckAuthFlowState(oauth2) < 3
        CkOAuth2::ckCancel(oauth2)
        Debug "No response from the browser!"
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    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 CkOAuth2::ckAuthFlowState(oauth2) = 5
        Debug "OAuth2 failed to complete."
        Debug CkOAuth2::ckFailureInfo(oauth2)
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    If CkOAuth2::ckAuthFlowState(oauth2) = 4
        Debug "OAuth2 authorization was denied."
        Debug CkOAuth2::ckAccessTokenResponse(oauth2)
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    If CkOAuth2::ckAuthFlowState(oauth2) <> 3
        Debug "Unexpected AuthFlowState:" + Str(CkOAuth2::ckAuthFlowState(oauth2))
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    Debug "OAuth2 authorization granted!"

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

    CkJsonObject::ckLoad(json,CkOAuth2::ckAccessTokenResponse(oauth2))
    CkJsonObject::setCkEmitCompact(json, 0)

    Debug "Access Token Response = " + CkJsonObject::ckEmit(json)

    ; 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"
    ; }

    Debug "Access Token = " + CkOAuth2::ckAccessToken(oauth2)

    ; Save the JSON access token response to a file for subsequent use..
    CkJsonObject::ckWriteFile(json,"qa_data/tokens/dropbox.json")


    CkOAuth2::ckDispose(oauth2)
    CkJsonObject::ckDispose(json)


    ProcedureReturn
EndProcedure