(Delphi DLL) USPS OAuth2 Client Credentials

See more OAuth2 Examples

For more information, see https://developers.usps.com/api/81

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, Http, HttpRequest, HttpResponse, StringBuilder, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
http: HCkHttp;
success: Boolean;
req: HCkHttpRequest;
resp: HCkHttpResponse;
sbResponseBody: HCkStringBuilder;
jResp: HCkJsonObject;
respStatusCode: Integer;
access_token: PWideChar;
token_type: PWideChar;
issued_at: Integer;
expires_in: Integer;
status: PWideChar;
scope: PWideChar;
issuer: PWideChar;
client_id: PWideChar;
application_name: PWideChar;
api_products: PWideChar;
public_key: PWideChar;

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

http := CkHttp_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 := CkHttpRequest_Create();
CkHttpRequest_AddParam(req,'grant_type','client_credentials');
CkHttpRequest_AddParam(req,'client_id','123456789');
CkHttpRequest_AddParam(req,'client_secret','A1B2C3D4E5');
CkHttpRequest_AddParam(req,'scope','ResourceA+ResourceB+ResourceC');

resp := CkHttp_PostUrlEncoded(http,'https://apis.usps.com/oauth2/v3/token',req);
if (CkHttp_getLastMethodSuccess(http) = False) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

sbResponseBody := CkStringBuilder_Create();
CkHttpResponse_GetBodySb(resp,sbResponseBody);

jResp := CkJsonObject_Create();
CkJsonObject_LoadSb(jResp,sbResponseBody);
CkJsonObject_putEmitCompact(jResp,False);

Memo1.Lines.Add('Response Body:');
Memo1.Lines.Add(CkJsonObject__emit(jResp));

respStatusCode := CkHttpResponse_getStatusCode(resp);
Memo1.Lines.Add('Response Status Code = ' + IntToStr(respStatusCode));
if (respStatusCode >= 400) then
  begin
    Memo1.Lines.Add('Response Header:');
    Memo1.Lines.Add(CkHttpResponse__header(resp));
    Memo1.Lines.Add('Failed.');
    CkHttpResponse_Dispose(resp);
    Exit;
  end;
CkHttpResponse_Dispose(resp);

// 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 := CkJsonObject__stringOf(jResp,'access_token');
token_type := CkJsonObject__stringOf(jResp,'token_type');
issued_at := CkJsonObject_IntOf(jResp,'issued_at');
expires_in := CkJsonObject_IntOf(jResp,'expires_in');
status := CkJsonObject__stringOf(jResp,'status');
scope := CkJsonObject__stringOf(jResp,'scope');
issuer := CkJsonObject__stringOf(jResp,'issuer');
client_id := CkJsonObject__stringOf(jResp,'client_id');
application_name := CkJsonObject__stringOf(jResp,'application_name');
api_products := CkJsonObject__stringOf(jResp,'api_products');
public_key := CkJsonObject__stringOf(jResp,'public_key');

CkHttp_Dispose(http);
CkHttpRequest_Dispose(req);
CkStringBuilder_Dispose(sbResponseBody);
CkJsonObject_Dispose(jResp);

end;