(Delphi DLL) Azure Storage: Download Blob to File

See more Azure Cloud Storage Examples

Sample code to download an Azure blob to a file.

For more information, see https://docs.microsoft.com/en-us/rest/api/storageservices/get-blob

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, Rest, AuthAzureStorage, Stream;

...

procedure TForm1.Button1Click(Sender: TObject);
var
rest: HCkRest;
bTls: Boolean;
port: Integer;
bAutoReconnect: Boolean;
success: Boolean;
azAuth: HCkAuthAzureStorage;
fileStream: HCkStream;
expectedStatus: Integer;
responseStr: PWideChar;

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

rest := CkRest_Create();

// Connect to the Azure Storage Blob Service
bTls := True;
port := 443;
bAutoReconnect := True;
// In this example, the storage account name is "chilkat".
success := CkRest_Connect(rest,'chilkat.blob.core.windows.net',port,bTls,bAutoReconnect);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

// Provide Azure Cloud credentials for the REST call.
azAuth := CkAuthAzureStorage_Create();
CkAuthAzureStorage_putAccessKey(azAuth,'AZURE_ACCESS_KEY');
// The account name used here should match the 1st part of the domain passed in the call to Connect (above).
CkAuthAzureStorage_putAccount(azAuth,'chilkat');
CkAuthAzureStorage_putScheme(azAuth,'SharedKey');
CkAuthAzureStorage_putService(azAuth,'Blob');
// This causes the "x-ms-version: 2021-08-06" header to be automatically added.
CkAuthAzureStorage_putXMsVersion(azAuth,'2021-08-06');
success := CkRest_SetAuthAzureStorage(rest,azAuth);

// Note: The application does not need to explicitly set the following
// headers: Content-Length, x-ms-date, Authorization.  These headers
// are automatically set by Chilkat.

// Setup a file stream for the download
fileStream := CkStream_Create();
CkStream_putSinkFile(fileStream,'qa_output/starfish.jpg');

// Indicate that the call to FullRequestNoBody should send the response body
// to fileStream if the response status code is 200.
// If a non-success response status code is received, then nothing
// is streamed to the output file and the error response is returned by FullRequestNoBody.
expectedStatus := 200;
CkRest_SetResponseBodyStream(rest,expectedStatus,True,fileStream);

// The Azure blob container is "test", the file is "starfish.jpg"
responseStr := CkRest__fullRequestNoBody(rest,'GET','/test/starfish.jpg');
if (CkRest_getLastMethodSuccess(rest) <> True) then
  begin
    // Examine the request/response to see what happened.
    Memo1.Lines.Add('response status code = ' + IntToStr(CkRest_getResponseStatusCode(rest)));
    Memo1.Lines.Add('response status text = ' + CkRest__responseStatusText(rest));
    Memo1.Lines.Add('response header: ' + CkRest__responseHeader(rest));
    Memo1.Lines.Add('response body (if any): ' + responseStr);
    Memo1.Lines.Add('---');
    Memo1.Lines.Add('LastRequestStartLine: ' + CkRest__lastRequestStartLine(rest));
    Memo1.Lines.Add('LastRequestHeader: ' + CkRest__lastRequestHeader(rest));
    Exit;
  end;

Memo1.Lines.Add('Success.');

CkRest_Dispose(rest);
CkAuthAzureStorage_Dispose(azAuth);
CkStream_Dispose(fileStream);

end;