(Delphi DLL) 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 for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, OAuth2, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
oauth2: HCkOAuth2;
url: PWideChar;
success: Boolean;
numMsWaited: Integer;
json: HCkJsonObject;

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

oauth2 := CkOAuth2_Create();

// The port should match the Authorized Redirect URL in your Dropbox app, 
// which would look like "http://localhost:3017/"
CkOAuth2_putListenPort(oauth2,3017);

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

CkOAuth2_putAuthorizationEndpoint(oauth2,'https://www.dropbox.com/oauth2/authorize');
CkOAuth2_putTokenEndpoint(oauth2,'https://api.dropboxapi.com/oauth2/token');

// Replace this with your actual Dropbox App Key
CkOAuth2_putClientId(oauth2,'DROPBOX_APP_KEY');

// This is for Require Proof Key for Code Exchange (PKCE)
// See OAuth2 PKCE Explained
CkOAuth2_putCodeChallenge(oauth2,True);
CkOAuth2_putCodeChallengeMethod(oauth2,'S256');

// Add token_access_type=offline to also get a refresh token in the response
CkOAuth2_AddAuthQueryParam(oauth2,'token_access_type','offline');

// Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
url := CkOAuth2__startAuth(oauth2);
if (CkOAuth2_getLastMethodSuccess(oauth2) <> True) then
  begin
    Memo1.Lines.Add(CkOAuth2__lastErrorText(oauth2));
    Exit;
  end;

Memo1.Lines.Add('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 := CkOAuth2_LaunchBrowser(oauth2,url);
if (success = False) then
  begin
    Memo1.Lines.Add(CkOAuth2__lastErrorText(oauth2));
    Exit;
  end;

// Wait for the user to approve or deny authorization in the browser.
numMsWaited := 0;
while (numMsWaited < 90000) and (CkOAuth2_getAuthFlowState(oauth2) < 3) do
  begin
    CkOAuth2_SleepMs(oauth2,100);
    numMsWaited := numMsWaited + 100;
  end;

// 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_getAuthFlowState(oauth2) < 3) then
  begin
    CkOAuth2_Cancel(oauth2);
    Memo1.Lines.Add('No response from the browser!');
    Exit;
  end;

// 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_getAuthFlowState(oauth2) = 5) then
  begin
    Memo1.Lines.Add('OAuth2 failed to complete.');
    Memo1.Lines.Add(CkOAuth2__failureInfo(oauth2));
    Exit;
  end;

if (CkOAuth2_getAuthFlowState(oauth2) = 4) then
  begin
    Memo1.Lines.Add('OAuth2 authorization was denied.');
    Memo1.Lines.Add(CkOAuth2__accessTokenResponse(oauth2));
    Exit;
  end;

if (CkOAuth2_getAuthFlowState(oauth2) <> 3) then
  begin
    Memo1.Lines.Add('Unexpected AuthFlowState:' + IntToStr(CkOAuth2_getAuthFlowState(oauth2)));
    Exit;
  end;

Memo1.Lines.Add('OAuth2 authorization granted!');

json := CkJsonObject_Create();
CkJsonObject_Load(json,CkOAuth2__accessTokenResponse(oauth2));
CkJsonObject_putEmitCompact(json,False);

Memo1.Lines.Add('Access Token Response = ' + CkJsonObject__emit(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"
// }

Memo1.Lines.Add('Access Token = ' + CkOAuth2__accessToken(oauth2));

// Save the JSON access token response to a file for subsequent use..
CkJsonObject_WriteFile(json,'qa_data/tokens/dropbox.json');

CkOAuth2_Dispose(oauth2);
CkJsonObject_Dispose(json);

end;