Delphi DLL Requires Chilkat v11.0.0+

Lower-Level REST API Methods (Google Cloud Storage)

See more REST Examples

The FullRequest* methods, such as FullRequestBinary, FullRequestMultipart, FullRequestNoBody, FullRequestStream, FullRequestString, etc. are high-level REST API methods that both send the request and receive the response. It is often the case that an application needs make a REST call, but with a finer level of control. The Chilkat REST API provides this feature. An application can break a REST call into the following parts:

1. Send the HTTP request. (via the SendReq* methods)
2. Receive the HTTP response header. (ReadResponseHeader)
3. Receive the HTTP response body. (via the ReadRespBody* methods)

This example demonstrates a REST call using SendReqStringBody, ReadResonseHeader, and ReadRespBodyString.

Delphi DLL

var
success: Boolean;
gAuth: HCkAuthGoogle;
rest: HCkRest;
bAutoReconnect: Boolean;
jsonReqBody: HCkJsonObject;
objVersioning: HCkJsonObject;
responseStatusCode: Integer;
responseBodyStr: PWideChar;

begin
success := False;

//  This example demonstrates a REST call using SendReqStringBody, ReadResonseHeader, and ReadRespBodyString.
//  It will create a bucket in Google Cloud Storage.

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

gAuth := CkAuthGoogle_Create();
//  Obtain an access token as shown in one of the following examples:
//  See Get Access Token using a Service Account JSON Key
//  See Get Access Token using a P12 File

rest := CkRest_Create();

//  Connect using TLS.
bAutoReconnect := True;
success := CkRest_Connect(rest,'www.googleapis.com',443,True,bAutoReconnect);

//  Provide the authentication credentials (i.e. the access key)
success := CkRest_SetAuthGoogle(rest,gAuth);

//  Build the JSON request body for creating a bucket.
//  The only required property is the "name", but we'll add more
//  to make a better example..
jsonReqBody := CkJsonObject_Create();
success := CkJsonObject_AddStringAt(jsonReqBody,-1,'name','chilkat-bucket-c');
success := CkJsonObject_AddStringAt(jsonReqBody,-1,'kind','storage#bucket');
success := CkJsonObject_AddStringAt(jsonReqBody,-1,'location','US');

objVersioning := CkJsonObject_Create();
CkJsonObject_AppendObject2(jsonReqBody,'versioning',objVersioning);
success := CkJsonObject_AddBoolAt(objVersioning,-1,'enabled',True);

//  Show the HTTP request body we'll be sending.
Memo1.Lines.Add(CkJsonObject__emit(jsonReqBody));

//  Add the required query parameter.
//  See https://cloud.google.com/storage/docs/json_api/v1/buckets/insert
success := CkRest_AddQueryParam(rest,'project','chilkattest-1050');

//  Add the Content-Type HTTP request header.
success := CkRest_AddHeader(rest,'Content-Type','application/json; charset=UTF-8');

//  Send the REST HTTP request.
success := CkRest_SendReqStringBody(rest,'POST','/storage/v1/b',CkJsonObject__emit(jsonReqBody));
if (success = False) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

//  Read the response header.
responseStatusCode := CkRest_ReadResponseHeader(rest);
if (responseStatusCode < 0) then
  begin
    //  We were unable to receive the response header.
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

if (responseStatusCode <> 200) then
  begin
    //  The response was not successful.  We'll still need to receive 
    //  the response body, which may contain an error message from the server.
    //  If the response has no body, then the method for reading the
    //  response body can still be called.  It will simply return with an empty
    //  response body.

    //  We can examine the response header and status text:
    Memo1.Lines.Add('Response status text: ' + CkRest__responseStatusText(rest));
    Memo1.Lines.Add('Response header: ' + CkRest__responseHeader(rest));
  end;

//  Read the response body.  In this case we're expecting it to be JSON..
responseBodyStr := CkRest__readRespBodyString(rest);
if (CkRest_getLastMethodSuccess(rest) <> True) then
  begin
    //  We were unable to receive the response body.
    //  Note: If the response did not include a body (such as for cases where
    //  the Content-Length header is 0, or if the response status code implicitly
    //  indicates no body, then ReadRespBodyString returns cktrue, and the
    //  responseBodyString will be an empty string.
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

//  Show the JSON response.
Memo1.Lines.Add('Json Response: ' + responseBodyStr);

CkAuthGoogle_Dispose(gAuth);
CkRest_Dispose(rest);
CkJsonObject_Dispose(jsonReqBody);
CkJsonObject_Dispose(objVersioning);