(Delphi DLL) Get GMail Message Metadata

Demonstrates how to get the metadata for each message in a list of message IDs.

For more information, see https://developers.google.com/gmail/api/v1/reference/users/messages/get

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, HttpResponse, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
http: HCkHttp;
jsonMsgIds: HCkJsonObject;
success: Boolean;
id: PWideChar;
i: Integer;
count_i: Integer;
resp: HCkHttpResponse;
jsonResponse: HCkJsonObject;

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

http := CkHttp_Create();

CkHttp_putAuthToken(http,'ACCESS_TOKEN');

CkHttp_putAccept(http,'application/json');

// Let's say we have the following JSON containing a list of message ID's

// {
//   "messages": [
//     {
//       "id": "1712bc1dc22da2a2",
//       "threadId": "1712bc1dc22da2a2"
//     },
//     {
//       "id": "1712b94fa2168040",
//       "threadId": "1712b94fa2168040"
//     },
//     {
//       "id": "1711e4bd96ded05e",
//       "threadId": "1711e4bd96ded05e"
//     },
//     {
//       "id": "1711de0d119e751e",
//       "threadId": "1711de0d119e751e"
//     },
//     {
//       "id": "1711c81a43050f59",
//       "threadId": "1711c81a43050f59"
//     },
//     {
//       "id": "1711c2c1516abce5",
//       "threadId": "1711c2c1516abce5"
//     },
//     {
//       "id": "1711c161e655c915",
//       "threadId": "1711c161e655c915"
//     },
//     {
//       "id": "171199c6e454558c",
//       "threadId": "171199c6e454558c"
//     },
//     {
//       "id": "17119474c8aa248e",
//       "threadId": "17119474c8aa248e"
//     }
//   ],
//   "nextPageToken": "16710921492249671162",
//   "resultSizeEstimate": 309
// }

// Normally your program would have the above JSON in a string variable (obtained from a previous call to get
// a list of message IDs from a GMail mailbox).  In this example, we'll load the JSON from a file.
jsonMsgIds := CkJsonObject_Create();
success := CkJsonObject_LoadFile(jsonMsgIds,'qa_data/json/gmail_message_ids.json');

i := 0;
count_i := CkJsonObject_SizeOfArray(jsonMsgIds,'messages');
while i < count_i do
  begin
    CkJsonObject_putI(jsonMsgIds,i);
    id := CkJsonObject__stringOf(jsonMsgIds,'messages[i].id');

    // Get the metadata for this message ID.
    CkHttp_SetUrlVar(http,'id',id);

    resp := CkHttp_QuickRequest(http,'GET','https://www.googleapis.com/gmail/v1/users/userId/messages/{$id}?format=metadata');
    if (CkHttp_getLastMethodSuccess(http) <> True) then
      begin
        Memo1.Lines.Add(CkHttp__lastErrorText(http));
        Exit;
      end;

    Memo1.Lines.Add('Response Status Code: ' + IntToStr(CkHttpResponse_getStatusCode(resp)));

    jsonResponse := CkJsonObject_Create();
    CkJsonObject_Load(jsonResponse,CkHttpResponse__bodyStr(resp));
    CkJsonObject_putEmitCompact(jsonResponse,False);
    Memo1.Lines.Add(CkJsonObject__emit(jsonResponse));

    if (CkHttpResponse_getStatusCode(resp) <> 200) then
      begin
        Memo1.Lines.Add('Failed.');
        CkHttpResponse_Dispose(resp);
        Exit;
      end;

    CkHttpResponse_Dispose(resp);

    i := i + 1;
  end;

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

CkHttp_Dispose(http);
CkJsonObject_Dispose(jsonMsgIds);
    CkJsonObject_Dispose(jsonResponse);

end;