Multiple DB connections in a single resource

[ertankucukoglu]

Hello,

Is it possible to use multiple database connections in the same resource? What I am looking for is a way to do something like below

  [Path('twodb'), Connection('MAIN_DB'), Connection('MYSQL_DB'), RolesAllowed('user')]
  TMyTwoDBResource = class
  protected
    [Context] UD: TMARSUniDAC;
    [Context] UD2: TMARSUniDAC;
  public
...

I can read database connection parameters from some settings file and connect to the second database writing my own code. However, it would be more convenient if something like above is available.

Thanks & Regards,
Ertan

[ertankucukoglu]

Multiple database usage in a single class seems to be already exists.

Below works just fine

  [Path('somepath'), Connection('MAIN_DB'), Connection('MYSQL_DB'), RolesAllowed('user')]
  TSomeResource = class
  protected
    [Context, Connection('MAIN_DB')] UD: TMARSUniDAC;
    [Context, Connection('MYSQL_DB')] UD2: TMARSUniDAC;
    ....

Thanks & Regards,
Ertan

[ertankucukoglu]

I though this is working but it didn't. Likely I made a mistake while testing.
Below seems to work fine for me. I need to take care of freeing the instance though.

[Path('somepath'), RolesAllowed('user')]
TSomeResource = class
protected
  [Context] UD: TMARSUniDAC;
  ....

In any class procedure/function secondary database can be accessed as below

procedure TSomeResource.UsesDoubleDB;
var
  LConnection: TUniConnection; // for the second database access
  LQuery1stDB: TUniQuery,
  LQuery2ndDB: TUniQuery;
begin
  LConnection := nil;
  LQuery1stDB := nil;
  LQuery2ndDB := nil;
  try
    LConnection := UD.CreateConnectionByDefName('SECOND_DB', nil); // Get a connection object for the SEDOND_DB

    LQuery1stDB := TUniQuery.Create(nil);
    LQuery1stDB.Connection := UD.Connection; // MAIN_DB connection

    LQuery2ndDB := TUniQuery.Create(nil);
    LQuery2ndDB.Connection := LConnection; // SECOND_DB connection
  finally
    LQuery1stDB.Free();
    LQuery2ndDB.Free();
    LConnection.Free();
  end;
end;

I am leaving the issue open as I still would like to know if there is an alternative version that the MARS engine has the control on the connection object freeing.

Thanks.