Lazarus Pascal

USPS OAuth2 Client Credentials

See more OAuth2 Examples

Get an OAuth2 access token for the United States Postal Service (USPS) REST API. Lazarus Pascal

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Http,
  Chilkat.HttpRequest,
  Chilkat.HttpResponse,
  Chilkat.StringBuilder,
  Chilkat.JsonObject;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  http: THttp;
  req: THttpRequest;
  resp: THttpResponse;
  sbResponseBody: TStringBuilder;
  jResp: TJsonObject;
  respStatusCode: Integer;
  access_token: string;
  token_type: string;
  issued_at: Integer;
  expires_in: Integer;
  status: string;
  scope: string;
  issuer: string;
  client_id: string;
  application_name: string;
  api_products: string;
  public_key: string;

begin
  success := False;

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

  http := THttp.Create;

  //  Implements the following CURL command:

  //  curl -X POST https://apis.usps.com/oauth2/v3/token \
  //    -H "Content-Type: application/x-www-form-urlencoded" \
  //    -d "grant_type=client_credentials" \
  //    -d "client_id=123456789" \
  //    -d "client_secret=A1B2C3D4E5" \
  //    -d "scope=ResourceA+ResourceB+ResourceC"

  //  Use the following online tool to generate HTTP code from a CURL command
  //  Convert a cURL Command to HTTP Source Code

  req := THttpRequest.Create;
  req.AddParam('grant_type','client_credentials');
  req.AddParam('client_id','123456789');
  req.AddParam('client_secret','A1B2C3D4E5');
  req.AddParam('scope','ResourceA+ResourceB+ResourceC');

  req.HttpVerb := 'POST';
  req.ContentType := 'application/x-www-form-urlencoded';

  resp := THttpResponse.Create;
  success := http.HttpReq('https://apis.usps.com/oauth2/v3/token',req,resp);
  if (success = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  sbResponseBody := TStringBuilder.Create;
  resp.GetBodySb(sbResponseBody);

  jResp := TJsonObject.Create;
  jResp.LoadSb(sbResponseBody);
  jResp.EmitCompact := False;

  WriteLn('Response Body:');
  WriteLn(jResp.Emit());

  respStatusCode := resp.StatusCode;
  WriteLn('Response Status Code = ' + respStatusCode);
  if (respStatusCode >= 400) then
    begin
      WriteLn('Response Header:');
      WriteLn(resp.Header);
      WriteLn('Failed.');
      Exit;
    end;

  //  Sample JSON response:
  //  (Sample code for parsing the JSON response is shown below)

  //  {
  //    "access_token": "eyJraWQiOiIxMDEwMTAiLCJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.eyJzdWIiOiIiLCJhdWQiOiJhZGRyZXNzZXMgaW50ZXJuYXRpb25hbC1wcmljZXMgc3Vic2NyaXB0aW9ucyBwYXltZW50cyBwaWNrdXAgdHJhY2tpbmcgbGFiZWxzIHNjYW4tZm9ybXMgY29tcGFuaWVzIHNlcnZpY2UtZGVsaXZlcnktc3RhbmRhcmRzIGxvY2F0aW9ucyBpbnRlcm5hdGlvbmFsLWxhYmVscyBwcmljZXMiLCJhenAiOiJoeXI3YjN2Q1J0cFl0QUhNMWE4Y2RVcmt5eUZtTmtiZyIsIm9yZ2FuaXphdGlvbl9pZCI6IjAiLCJpc3MiOiJ1cm46XC9cL2FwaS51c3BzLmNvbSIsImV4cCI6MTY4MDkxNzc4NiwiaWF0IjoxNjgwODg4OTg2LCJqdGkiOiI3YjU5MzJlMS05NjIxLTQzZDAtYTMyNy0xMzIxYWVjNzJjZGYifQ.QzrUxlT2rG4jvYbMDGnk23j8ZYfHJcdXPKR9CbSmcKeVpURaHhEMpPB6K4x5ut3xxeEGSzeE5VRz8vixI4iqyHsD8rSdkLTPHy0iovUHOZQBAJVQ6hii9jpLhxUXmiTtH3jKzSj_f2fuNmZbIGhf-CR2FBeWF-aBPzEDEMV95nkCUMfW_Z2BmkbraSfvQZxkCO-cLrMAwlYcrzUtaJ7vnazeQB4sep5BBHBEvsa4kfq6_tz6BAKgv3R7cI2NkSv-wgy_IGoTjVCMTS8mJHGs_t8cWCO8-z4lxW1tUwIBKOCUDpmEEnGgiG6Sl0C_gGl4bZ5cDSl4IgPpcOVi9jZ7LA",
  //    "token_type": "Bearer",
  //    "issued_at": 1680888985929,
  //    "expires_in": 28799,
  //    "status": "approved",
  //    "scope": "addresses international-prices subscriptions payments pickup tracking labels scan-forms companies service-delivery-standards locations international-labels prices",
  //    "issuer": "api.usps.com",
  //    "client_id": "hyr7b3vCRtpYtAHM1a8cdUrkyyFmNkbg",
  //    "application_name": "Silver Shipper Developer",
  //    "api_products": "[Shipping-Silver]",
  //    "public_key": "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"
  //  }

  //  Sample code for parsing the JSON response...
  //  Use the following online tool to generate parsing code from sample JSON:
  //  Generate Parsing Code from JSON

  access_token := jResp.StringOf('access_token');
  token_type := jResp.StringOf('token_type');
  issued_at := jResp.IntOf('issued_at');
  expires_in := jResp.IntOf('expires_in');
  status := jResp.StringOf('status');
  scope := jResp.StringOf('scope');
  issuer := jResp.StringOf('issuer');
  client_id := jResp.StringOf('client_id');
  application_name := jResp.StringOf('application_name');
  api_products := jResp.StringOf('api_products');
  public_key := jResp.StringOf('public_key');


  http.Free;
  req.Free;
  resp.Free;
  sbResponseBody.Free;
  jResp.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.