(Delphi DLL) DVLA Vehicle Enquiry Service

Demonstrates how to make a call to the DVLA Vehicle Enquiry API to get vehicle details of a specified vehicle. It uses the vehicle registration number as input to search and provide details of the vehicle.

For more information, see https://developer-portal.driver-vehicle-licensing.api.gov.uk/apis/vehicle-enquiry-service/vehicle-enquiry-service-description.html

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, StringBuilder, HttpResponse, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
http: HCkHttp;
success: Boolean;
json: HCkJsonObject;
resp: HCkHttpResponse;
sbResponseBody: HCkStringBuilder;
jResp: HCkJsonObject;
respStatusCode: Integer;
artEndDate: PWideChar;
co2Emissions: Integer;
colour: PWideChar;
engineCapacity: Integer;
fuelType: PWideChar;
make: PWideChar;
markedForExport: Boolean;
monthOfFirstRegistration: PWideChar;
motStatus: PWideChar;
registrationNumber: PWideChar;
revenueWeight: Integer;
taxDueDate: PWideChar;
taxStatus: PWideChar;
typeApproval: PWideChar;
wheelplan: PWideChar;
yearOfManufacture: Integer;
euroStatus: PWideChar;
realDrivingEmissions: PWideChar;
dateOfLastV5CIssued: 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://driver-vehicle-licensing.api.gov.uk/vehicle-enquiry/v1/vehicles \
//   -H "x-api-key: supplied API key" \
//   -H "Accept: application/json" \
//   -d '{"registrationNumber": "ABC1234"}'

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

// Use this online tool to generate code from sample JSON:
// Generate Code to Create JSON

// The following JSON is sent in the request body.

// {
//   "registrationNumber": "ABC1234"
// }

json := CkJsonObject_Create();
CkJsonObject_UpdateString(json,'registrationNumber','ABC1234');

CkHttp_SetRequestHeader(http,'Accept','application/json');
CkHttp_SetRequestHeader(http,'x-api-key','supplied API key');

resp := CkHttp_PostJson3(http,'https://driver-vehicle-licensing.api.gov.uk/vehicle-enquiry/v1/vehicles','application/json',json);
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)

// {
//   "artEndDate": "2025-02-28",
//   "co2Emissions": 135,
//   "colour": "BLUE",
//   "engineCapacity": 2494,
//   "fuelType": "PETROL",
//   "make": "ROVER",
//   "markedForExport": false,
//   "monthOfFirstRegistration": "2004-12",
//   "motStatus": "No details held by DVLA",
//   "registrationNumber": "ABC1234",
//   "revenueWeight": 1640,
//   "taxDueDate": "2007-01-01",
//   "taxStatus": "Untaxed",
//   "typeApproval": "N1",
//   "wheelplan": "NON STANDARD",
//   "yearOfManufacture": 2004,
//   "euroStatus": "EURO 6 AD",
//   "realDrivingEmissions": "1",
//   "dateOfLastV5CIssued": "2016-12-25"
// }

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

artEndDate := CkJsonObject__stringOf(jResp,'artEndDate');
co2Emissions := CkJsonObject_IntOf(jResp,'co2Emissions');
colour := CkJsonObject__stringOf(jResp,'colour');
engineCapacity := CkJsonObject_IntOf(jResp,'engineCapacity');
fuelType := CkJsonObject__stringOf(jResp,'fuelType');
make := CkJsonObject__stringOf(jResp,'make');
markedForExport := CkJsonObject_BoolOf(jResp,'markedForExport');
monthOfFirstRegistration := CkJsonObject__stringOf(jResp,'monthOfFirstRegistration');
motStatus := CkJsonObject__stringOf(jResp,'motStatus');
registrationNumber := CkJsonObject__stringOf(jResp,'registrationNumber');
revenueWeight := CkJsonObject_IntOf(jResp,'revenueWeight');
taxDueDate := CkJsonObject__stringOf(jResp,'taxDueDate');
taxStatus := CkJsonObject__stringOf(jResp,'taxStatus');
typeApproval := CkJsonObject__stringOf(jResp,'typeApproval');
wheelplan := CkJsonObject__stringOf(jResp,'wheelplan');
yearOfManufacture := CkJsonObject_IntOf(jResp,'yearOfManufacture');
euroStatus := CkJsonObject__stringOf(jResp,'euroStatus');
realDrivingEmissions := CkJsonObject__stringOf(jResp,'realDrivingEmissions');
dateOfLastV5CIssued := CkJsonObject__stringOf(jResp,'dateOfLastV5CIssued');

CkHttp_Dispose(http);
CkJsonObject_Dispose(json);
CkStringBuilder_Dispose(sbResponseBody);
CkJsonObject_Dispose(jResp);

end;