Re: [wxperl-users] Grids and Data

[Mattia B. <mat...@li...>]

Il Tue, 2 Dec 2003 10:23:17 +0100 Thomas Klausner <do...@zs...> ha scritto:

  Hello,

> I'm currently developing a small application for in-house use.
> Basically,
> it's a database front end, i.e. users should be able to view,
> insert, edit,
> delete some data.
> 
> I got some basic stuff working, but I'm wondering if there is a
> "standard"
> way of generating a Wx::Grid from database data.
  No, there isn't.
 
> Here's what I'm doing:
> in MyApp::new, I set up a panel, and generate a grid
> 
>   my $grid=Wx::Grid->new($panel,-1,wxDefaultPosition,[750,300]);
> 
> I fetch stuff from a database (using Class::DBI):
> 
>   my @ks=ZCont::DB::Kostenstelle->retrieve_all;
>   my $rows=@ks || 1;
>   $grid->CreateGrid($rows,7);
> 	      
>   foreach my $kostenstelle (@ks) {
>       my $row=0;
>       my $col=0;
>       foreach(qw(kostenstelle titel beginn ende leitung overhead
> budget)) {
> 	   $grid->SetCellValue($row,$col,$kostenstelle->$_);
>            $col++;
>       }
>       $row++;
>   }
> 
> (If you're not familiar with Class::DBI : @ks is an array containing
> objects. Each object as accessors which correlate to a column)
> 
> This is working as expected, but there might be some better ways to
> set up a
> Grid ?
  Using a custom Wx::GridTable (there is a xample in the wxPerl demo)
might be a good idea.

> Additionally, some more questions (I'm coming from a Web
> background..):
> 
> Say I've got 1000 rows in a table, but only want to display 100 in
> a Grid,
> would I:

> * fetch all 1000 columns and add/delete them from the Grid if the
> user pages
>   up/down
> 
> * fetch only 100, delete them when they disappear from the screen,
> and fetch
>   new ones if they are needed (this is what I would do in a Web
> Environment,
>   which is stateless)
> 
> * something completly different?
  It depends. I think that, for a GUI application, it is better to display
all 1000 rows at once and let the user scroll them using the scrollbars.
If you use a custom Wx::GridTable you can fetch the rows on demand
(thus avoiding fetching a large amount of data the user might not need/look at).

HTH
Mattia

P.S.: I think that a generic "Database Grid" might be a good candidate for CPAN.
      if you feel like releasing it