Copy Sqlite DB to tethered app

[GreatDayDan 0]

I have created a tethered app. The server needs to copy a Sqlite db and stream it to the client.

I get the db with this code:

procedure TfmxServer.actStreamTheDbExecute(Sender: TObject);
var
  ms: TMemoryStream;
begin
  ms := tmemorystream.Create;
  ms := dmplanner.GetDbAsStream;  // get it from the datamodule
  ms.Position := 0;
  thrprofServer.SendStream(thrmanServer.RemoteProfiles.First,
          'Stream_TheDB', ms);  // send it to the client
end;


function TdmPlanner.GetDbAsStream: TMemoryStream;  // datamodule
var
  fs: TFilestream;
  ms: TMemoryStream;
begin
  fs := tfilestream.Create(consqlite.Params.Values['Database'] , fmOpenRead);
  ms := tmemorystream.Create;
  try
   ms.loadfromstream(fs); // ms.size = 315392, file size = (315,392 bytes
   result := ms;               // so I am getting the full db3 file.
   result.Position := 0;
  finally
   freeandnil(fs);
   freeandnil(ms); // does this kill the result?
  end;
end;

I catch the stream and to write the db with this code:

procedure TfrmMobile_Client_Main.DoStreamTheDb(
  const Aresource: TremoteResource);
var
  fs: TFilestream;
  ms: TMemoryStream;
begin
  fs := tfilestream.Create
    (dmplannerclient.consqlite.Params.Values['Database'] ,
    fmopenreadwrite or fmCreate);
  try
   ms := TMemoryStream.Create;
   ms := TMemoryStream(AResource.Value.AsStream);
   ms.Position := 0;    // ms.size = 315392, so I got the whole file.
   ms.SaveToStream(fs);
  dmPlannerClient.FillLbx(lbxRecipeNames);
  // now fill a listbox, but when I open a query, I get
  //  [FireDAC][Phys][SQLite] ERROR: unable to open database file.
  finally
   freeandnil(fs);
   freeandnil(ms);
  end;
end;

So my question is, How do I copy the db to the client and then use it on the client?

Better yet, How do I an in-memory db instead of an on-disk db? I have tried setting the FDConnection filename to :memory: but that did not work.

Delphi CE Rio 10.3.2

Thanks...Dan'l' +

[Rollo62 536]

Sorry, TLDR.

 

These lines are a little doubtful to me.

ms := TMemoryStream.Create;

//<-- This is overwriting the formerly created TMemoryStream.
ms := dmplanner.GetDbAsStream;  

I would expect some kind of CopyStream here.

[Markus Kinzler 174]

Quote

These lines are a little doubtful to me.

Seems to be taken from:

https://stackoverflow.com/questions/55455875/copy-database-to-tethered-client

 

The manual creation of the Stream leads to a memory leak.

 

I would prefer the stream as inputvar.

Quote

How do I copy the db to the client and then use it on the client?

 ms.SaveToStream(fs);

Should write it to the client.

[Hans J. Ellingsgaard 21]

On 4/1/2019 at 2:11 PM, GreatDayDan said:

Better yet, How do I an in-memory db instead of an on-disk db? I have tried setting the FDConnection filename to :memory: but that did not work.

You can use FDMemTables, they can load and save from streams, files and other datasets.