Inherit from TClientDataSet - strange problem - Thread - go-pugleaf

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2 total messages Started by John Molyneux Wed, 24 Jun 2009 08:44

Inherit from TClientDataSet - strange problem

#183

Author: John Molyneux
Date: Wed, 24 Jun 2009 08:44

65 lines
2936 bytes

Hi.

I'm trying to use a TClientDataSet as a native type for transporting data 
around a bunch of network applications, purely because the SaveToStream and 
LoadFromStream are A LOT faster than KbmMemTable's similar methods, but I'm 
having a bizarre problem.

I'm creating a new class, inherited from TClientDataSet, so that I can add 
an extra couple of properties and methods, and this is causing a problem.

If you create a new console app and paste the code below into it, you'll see 
my issue.

Can anyone (please!!!) advise me on how to resolve this rather strange 
problem??

Thanks in advance,

John.


//    Start of 
application --------------------------------------------------------------------------------

program ClientDataSetDates;

{$APPTYPE CONSOLE}

uses
  DBClient,
  DB;

type
 TMyClientDataSet = class(TClientDataSet)
  end;

var
 ClientDataSet: TClientDataSet;
  MyClientDataSet: TMyClientDataSet;
begin
 ClientDataSet := TClientDataSet.Create(nil);

  ClientDataSet.FieldDefs.Add('Field1', ftDateTime);
  ClientDataSet.CreateDataSet;

  ClientDataSet.Append;
  ClientDataSet.FieldByName('Field1').Value := '5/11/1955 11:30:15';
  ClientDataSet.Post;

  MyClientDataSet := TMyClientDataSet.Create(nil);
  MyClientDataSet.Data := ClientDataSet.Data;
  MyClientDataSet.First;

  Writeln('ClientDataSet : ' + 
ClientDataSet.FieldByName('Field1').AsString);
  Writeln('MyClientDataSet : ' + 
MyClientDataSet.FieldByName('Field1').AsString);

  Writeln('');
  Writeln('Press enter to exit');
  Readln;
end.

//    End of 
application --------------------------------------------------------------------------------

Re: Inherit from TClientDataSet - strange problem

#184

Author: John Molyneux
Date: Wed, 24 Jun 2009 10:17

78 lines
3325 bytes

Just an extra note on this problem.

I've saved both ClientDataSet and MyClientDataSet as XML, and they are 
identical.  It appears that the problem occurs when doing Field.Value (or 
Field.AsDateTime, Field.AsString, Field.AsFloat etc. on the ftDateTime 
field).

Still gagging for some help with this ridiculous problem!

"John Molyneux" <johncmolyneux@ntlworld.com> wrote in message 
news:0Il0m.11084$xw7.10600@newsfe26.ams2...
> Hi.
>
> I'm trying to use a TClientDataSet as a native type for transporting data 
> around a bunch of network applications, purely because the SaveToStream 
> and LoadFromStream are A LOT faster than KbmMemTable's similar methods, 
> but I'm having a bizarre problem.
>
> I'm creating a new class, inherited from TClientDataSet, so that I can add 
> an extra couple of properties and methods, and this is causing a problem.
>
> If you create a new console app and paste the code below into it, you'll 
> see my issue.
>
> Can anyone (please!!!) advise me on how to resolve this rather strange 
> problem??
>
> Thanks in advance,
>
> John.
>
>
> //    Start of 
> application --------------------------------------------------------------------------------
>
> program ClientDataSetDates;
>
> {$APPTYPE CONSOLE}
>
> uses
>  DBClient,
>  DB;
>
> type
> TMyClientDataSet = class(TClientDataSet)
>  end;
>
> var
> ClientDataSet: TClientDataSet;
>  MyClientDataSet: TMyClientDataSet;
> begin
> ClientDataSet := TClientDataSet.Create(nil);
>
>  ClientDataSet.FieldDefs.Add('Field1', ftDateTime);
>  ClientDataSet.CreateDataSet;
>
>  ClientDataSet.Append;
>  ClientDataSet.FieldByName('Field1').Value := '5/11/1955 11:30:15';
>  ClientDataSet.Post;
>
>  MyClientDataSet := TMyClientDataSet.Create(nil);
>  MyClientDataSet.Data := ClientDataSet.Data;
>  MyClientDataSet.First;
>
>  Writeln('ClientDataSet : ' + 
> ClientDataSet.FieldByName('Field1').AsString);
>  Writeln('MyClientDataSet : ' + 
> MyClientDataSet.FieldByName('Field1').AsString);
>
>  Writeln('');
>  Writeln('Press enter to exit');
>  Readln;
> end.
>
> //    End of 
> application --------------------------------------------------------------------------------
>
>

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