(Delphi DLL) PayPal -- Get an OAuth 2.0 Access Token

Demonstrates how to send a request to get a PayPal OAuth2 access token. Sends an HTTP request equivalent to the following:

curl https://api.sandbox.paypal.com/v1/oauth2/token \
  -H "Accept: application/json" \
  -H "Accept-Language: en_US" \
  -u "Client-Id:Secret" \
  -d "grant_type=client_credentials"

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, StringBuilder, Rest, JsonObject, CkDateTime;

...

procedure TForm1.Button1Click(Sender: TObject);
var
rest: HCkRest;
bAutoReconnect: Boolean;
success: Boolean;
responseStr: PWideChar;
json: HCkJsonObject;
dateTime: HCkDateTime;
bLocalTime: Boolean;
dtNow: Integer;
sbResponse: HCkStringBuilder;
bEmitBom: Boolean;

begin
// Note: Requires Chilkat v9.5.0.64 or greater.

// This requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

rest := CkRest_Create();

// Make the initial connection.
// A single REST object, once connected, can be used for many PayPal REST API calls.
// The auto-reconnect indicates that if the already-established HTTPS connection is closed,
// then it will be automatically re-established as needed.
bAutoReconnect := True;
success := CkRest_Connect(rest,'api.sandbox.paypal.com',443,True,bAutoReconnect);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

// Duplicate this request:

// 	curl https://api.sandbox.paypal.com/v1/oauth2/token \
// 	  -H "Accept: application/json" \
// 	  -H "Accept-Language: en_US" \
// 	  -u "Client-Id:Secret" \
// 	  -d "grant_type=client_credentials"

CkRest_AddHeader(rest,'Accept','application/json');
CkRest_AddHeader(rest,'Accept-Language','en_US');

// For additional help on where to find  your client ID and API secret, see PayPal Client_ID and API_Secret
CkRest_SetAuthBasic(rest,'PAYPAL_REST_API_CLIENT_ID','PAYPAL_REST_API_SECRET');

CkRest_AddQueryParam(rest,'grant_type','client_credentials');

responseStr := CkRest__fullRequestFormUrlEncoded(rest,'POST','/v1/oauth2/token');
if (CkRest_getLastMethodSuccess(rest) <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

Memo1.Lines.Add(CkRest__lastRequestHeader(rest));

// A sample response:

// 	{
// 	  "scope": "https://api.paypal.com/v1/payments/.* https://api.paypal.com/v1/vault/credit-card https://api.paypal.com/v1/vault/credit-card/.*",
// 	  "access_token": "EEwJ6tF9x5WCIZDYzyZGaz6Khbw7raYRIBV_WxVvgmsG",
// 	  "token_type": "Bearer",
// 	  "app_id": "APP-6XR95014BA15863X",
// 	  "expires_in": 28800
// 	}

json := CkJsonObject_Create();
CkJsonObject_Load(json,responseStr);
CkJsonObject_putEmitCompact(json,False);

// Check the response status code.  A 200 indicates success..
if (CkRest_getResponseStatusCode(rest) <> 200) then
  begin
    Memo1.Lines.Add(CkJsonObject__emit(json));
    Memo1.Lines.Add('Failed.');
    Exit;
  end;

// Given that the access token expires in approx 8 hours,
// let's record the date/time this token was created.
// This will allow us to know beforehand if the token
// is expired (and we can then fetch a new token).
dateTime := CkDateTime_Create();
bLocalTime := False;
dtNow := CkDateTime_GetAsUnixTime(dateTime,bLocalTime);
CkJsonObject_AppendInt(json,'tokenCreateTimeUtc',dtNow);

// Examine the access token and save to a file.
Memo1.Lines.Add('Access Token: ' + CkJsonObject__stringOf(json,'access_token'));
Memo1.Lines.Add('Full JSON Response:');
Memo1.Lines.Add(CkJsonObject__emit(json));

sbResponse := CkStringBuilder_Create();
CkStringBuilder_Append(sbResponse,CkJsonObject__emit(json));
bEmitBom := False;
CkStringBuilder_WriteFile(sbResponse,'qa_data/tokens/paypal.json','utf-8',bEmitBom);

CkRest_Dispose(rest);
CkJsonObject_Dispose(json);
CkDateTime_Dispose(dateTime);
CkStringBuilder_Dispose(sbResponse);

end;