How to add all fields without opening dataset? - delphi

Question

I'm using TFIBDataSet (Firebird dataset component) and I'm trying to automatically create all fields at runtime, without loading any record into the dataset.
Here is the code of my test:
uses
FIBDatabase, FIBDataSet, Dialogs;
...
var
Db : TFIBDataBase;
Tr : TFIBTransaction;
Dst : TFIBDataSet;
begin
//connection
Db := TFIBDatabase.Create(Self);
Db.ConnectParams.UserName := 'SYSDBA';
Db.ConnectParams.Password := 'masterkey';
Db.DatabaseName := 'localhost:mydatabase.fdb';
Db.SQLDialect := 3;
Db.Connected := True;
//transaction
Tr := TFIBTransaction.Create(Self);
Tr.DefaultDatabase := Db;
Tr.Active := True;
//dataset
Dst := TFIBDataSet.Create(Self);
Dst.Database := Db;
Dst.Transaction := Tr;
Dst.SelectSQL.Text := 'SELECT * FROM rdb$database';
//...
ShowMessage(IntToStr(Dst.FieldCount));
end;
The previous code produces '0' as output..
I've tried using Dst.Open() and it produces '5', but it also executes the SQL query.

Answer 1

I did it by calling FieldDefs.Update and creating the fields from the FieldDefs list.
uses
FIBDatabase, FIBDataSet, Dialogs;
...
var
Db : TFIBDataBase;
Tr : TFIBTransaction;
Dst : TFIBDataSet;
I : integer;
begin
//connection
Db := TFIBDatabase.Create(Self);
Db.ConnectParams.UserName := 'SYSDBA';
Db.ConnectParams.Password := 'masterkey';
Db.DatabaseName := 'localhost:mydatabase.fdb';
Db.SQLDialect := 3;
Db.Connected := True;
//transaction
Tr := TFIBTransaction.Create(Self);
Tr.DefaultDatabase := Db;
Tr.Active := True;
//dataset
Dst := TFIBDataSet.Create(Self);
Dst.Database := Db;
Dst.Transaction := Tr;
Dst.SelectSQL.Text := 'SELECT * FROM rdb$database';
//create fields
Dst.FieldDefs.Update();
for I := 0 to Dst.FieldDefs.Count - 1 do
Dst.FieldDefs[I].CreateField(Dst);
ShowMessage(IntToStr(Dst.FieldCount));
end;