Datamodule, what are they for? are they working?

[gypsymauro]

I created a new project , I added a new datamodule and then
on it I created a new postgresql connection, a transaction a datasource and a tquery object,
I connected them then I wrote a sql statement

select field1 from table, I run the query with the green button available when the query object
is connected to the db and it works, and it displays data.. but when I try to add fields
it says me

"it was not possible to get the dataset field's list check dataset settings, access violation"

then I create the same object on a form and everything goes right..
so are the Datamodule broken? I tried this on linux with 0.9.26 and 0.9.28


I hope there is a solution cause Datamodule are so usefull to keep ordered things

tank you
Mauro

[a.atalla]

i have similar problem here with lazarus 0.9.19 fromsvn  fpc2.4

i use datamodule contains sqlite3dataset and a datasource
when i try executing the following code in the main unit
i get the Access violation error

Code: [Select]

procedure TfrmMain.FormCreate(Sender: TObject);
begin
     DM.Sqlite3Dataset1.FileName:='st4.db';
     DM.Sqlite3Dataset1.TableName:='equipment';
     DM.Sqlite3Dataset1.Open;
end;   


[bflm]

i have similar problem here with lazarus 0.9.19 fromsvn  fpc2.4

i use datamodule contains sqlite3dataset and a datasource
when i try executing the following code in the main unit
i get the Access violation error

Code: [Select]

procedure TfrmMain.FormCreate(Sender: TObject);
begin
     DM.Sqlite3Dataset1.FileName:='st4.db';
     DM.Sqlite3Dataset1.TableName:='equipment';
     DM.Sqlite3Dataset1.Open;
end;   


Was a valid, non nil value ever assigned to 'DM' at the time 'TfrmMain.FormCreate' gets invoked? Can't figure out that from the snippet alone...

[davesimplewear]

also in the project form create is the datamodule the first form created? This will result in an error if not.

Regards
Dave