M. Toussaint

Hi,

From our application we use several procedures and functions to upload files to AWS S3 and also download text-like files from AWS S3.

We use the function below to get the contents of text-like files (.SVG, .TXT, .CSV) from S3, but we have no idea how to (download and) process binary files.
 

function S3Get_Object_AsString(const bucket, key: string): string;
var
  pyKey            : TPythonDelphiVar;
  pyBucket         : TPythonDelphiVar;
  pyObj            : TPythonDelphiVar;
  PyEngine         : IPyEngineAndGIL;
  pyError          : TPythonDelphiVar;

  Script          : TStringList;
  cModuleName     : AnsiString;

begin
  pyKey         := TPythonDelphiVar.Create(nil);
  pyBucket      := TPythonDelphiVar.Create(nil);
  pyObj         := TPythonDelphiVar.Create(nil);
  pyError       := TPythonDelphiVar.Create(nil);

  script := TStringList.Create;
  try
    PyEngine    := TPyEngineAndGIL.Create;
    cModuleName := AnsiString(TGUID.NewGuid.ToString);


    pyBucket.Engine   := PyEngine.getPyEngine;
    pyBucket.VarName  := 'BUCKET';
    pyBucket.Module   := cModuleName;
    pyBucket.Initialize;
    pyBucket.Value    := bucket;

    pyKey.Engine  := PyEngine.getPyEngine;
    pyKey.VarName := 'S3KEY';
    pyKey.Module  := cModuleName;
    pyKey.Initialize;
    pyKey.Value   := key;

    pyObj.Engine   := PyEngine.getPyEngine;
    pyObj.VarName  := 'OBJ';
    pyObj.Module   := cModuleName;
    pyObj.Initialize;

    pyError.Engine  := PyEngine.getPyEngine;
    pyError.VarName := 'ERROR';
    pyError.Module  := cModuleName;
    pyError.Initialize;
    pyError.Value   := '';

    InitBotoClient(Script);

    Script.Add('import json ');
    Script.Add('from botocore.exceptions import ClientError ');

    Script.Add('s3_client = client(''s3'')');

    Script.Add('try: ' );
    Script.Add('    s3_object = s3_client.get_object(Bucket=BUCKET.VALUE, Key=S3KEY.VALUE)');
    Script.Add('    OBJ.VALUE = s3_object[''Body''].read()');
    Script.Add('except ClientError as e: ');
    Script.Add('    print("Get Object failed:" + e.response[''Error''][''Message''])');
    Script.Add('else:');
    Script.Add('    print("Get Object:" + BUCKET.VALUE + "-" + S3KEY.VALUE)');


    PyEngine.getPyEngine.ExecModule := cModuleName;
    PyEngine.getPyEngine.ExecStrings(Script);

    if pyError.ValueAsString <> '' then
    begin
      //Log(pyError.ValueAsString  + 'bucket: ' + bucket + ' key:' + key , 'E');
      result := '';
    end
    else
    begin
      if VarIsStr(pyObj.Value) then result := pyObj.Value else result := '';
    end;


  finally
    Script.Free;
    pyBucket.Finalize;
    pyKey.Finalize;
    pyObj.Finalize;
    pyError.Finalize;

    pyBucket.Free;
    pyKey.Free;
    pyObj.Free;
    pyError.Free;
  end;
end;

So far we found an alternative for downloading a file object from S3, but how to process this in Delphi?

    Script.Add('import json ');
    Script.Add('import io ');
    Script.Add('from botocore.exceptions import ClientError ');

    Script.Add('s3_client = client(''s3'')');
    Script.Add('io_stream = io.BytesIO()');

    Script.Add('try: ' );
    // Script.Add('    s3_object = s3_client.get_object(Bucket=BUCKET.VALUE, Key=S3KEY.VALUE, )');
    // Script.Add('    OBJ.VALUE = s3_object[''Body''].read()');
    // Use download_fileobj to gat a file-like object
    Script.Add('   s3_client.download_fileobj(Bucket=BUCKET.VALUE, Key=S3KEY.VALUE, Fileobj=io_stream)');
    Script.Add('   io_stream.seek(0)');
    Script.Add('   OBJ.VALUE = io_stream.getvalue()');
    Script.Add('except ClientError as e: ');
    Script.Add('    print("Get Object failed:" + e.response[''Error''][''Message''])');
    Script.Add('else:');
    Script.Add('    print("Get Object:" + BUCKET.VALUE + "-" + S3KEY.VALUE)');

I just got an answer from Embarcadero in which they state API 30 is not officially supported with 10.4.2. They plan on supporting API 30 in Delphi 10.5....