Poincare has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to use CGI::Application to make a simple web blog. Here's my code: 
package Bloggie;
use base qw(CGI::Application);
use CGI::Carp qw/fatalsToBrowser/;
use CGI::Application::Plugin::TT;
use DB_File;

sub setup {
        my $self=shift;
        $self->start_mode('start');
        $self->mode_param('rm');
        $self->run_modes(
                'start' => 'start',
                'new post form' => 'new_post_form',
                'new post success' => 'new_post_success',
                'redirect' => 'redirect',
        )
}

## overrided so CGI.pm can be replaced by CGI::Simple
sub cgiapp_get_query {
        require CGI::Simple;
        CGI::Simple->new();
}
## set up preliminary stuff like opening the database.
sub cgiapp_init {
        my $self = shift;
        my $dataname = "data.dbm";
        my %database;

        dbmopen(%database, $dataname, 0666) or die "Can't open $datana
+me: $!\n";

        $self->{DATA}=\%database;
}

## displays posts
sub start {
        my $self = shift;
        my $templatename = "start.tt";
        my %database = %{$self->{DATA}};
        my $posts = $database{POSTS};

        my $vars = {
                                "posts" => $posts,
                                };
        return $self->tt_process($templatename, $vars);
}

## displays form to create new pots
sub new_post_form {
        my $self = shift;
        my $templatename = "new_post_form.tt";

        return $self->tt_process($templatename);
}

## displayed on success of a posts
## also writes to database the post that was submitted by new_post_for
+m
sub new_post_success {
        my $self = shift;
        my $templatename = "new_post_success.tt";
        my %database = %{$self->{DATA}};
        my @posts=();
        my $post;

        #get current posts from database, if they're there
        #if not, make an empty array.
        if(defined($database{POSTS})) {
                @posts = @{$database{POSTS}};
        }

        #get CGI object
        my $query = $self->query();

        #get parameters
        my $title = $self->param('title');
        my $content = $self->param('content');
        my $post = {
                                title => $title,
                                content => $content,
                                };

        my $vars = {
                                title => $title,
                                content => $content,
                                };
        push(@posts, $post);

        $database{POSTS}=\@posts;

        return $self->tt_process($templatename, $vars);
}
1;

[download]
The functions are called in the exact order that they are in. As in, start first, new_post_form next and so on. The thing is, I have my template in new_post_success show me the values of $title and $content and they turn out to be empty! As expected, the central page of the blog never changes (i.e. start() which lists all the current blog entries)! What am I doing wrong? How can I fix it? Also, please reply if you need to see the templates in order to find the solution and I will post them.

Replies are listed 'Best First'.
Re: CGI::Application giving blank forms
by wfsp (Abbot) on Mar 31, 2010 at 07:18 UTC
    See if this helps. 
    my $title = $self->param(q{title});

    [download]
    should be something like 
    my $q = $self->query;
my $title = $q->param(q{title});

    [download]
    $self->param(xxx) returns params set by, say, your instance script. You need the params from the query which in CGI::A is in $self->query.

    update: fixed $q->param(q{title});

[reply]
[d/l]
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Re: CGI::Application giving blank forms
by Khen1950fx (Canon) on Mar 31, 2010 at 07:10 UTC
    I fixed a few minor errors in your script. Try this and see if it helps:
    #!/usr/bin/perl

package Bloggie;

use base qw(CGI::Application);

use strict;
use warnings;
use CGI::Carp qw/fatalsToBrowser/;
use CGI::Application::Plugin::TT;
use DB_File;

sub setup {
    my $self = shift @_;
    $self->start_mode('start');
    $self->mode_param('rm');
    $self->run_modes(
        'start'            => 'start',
        'new post form'    => 'new_post_form',
        'new post success' => 'new_post_success',
        'redirect'         => 'redirect',
    );
}

sub cgiapp_get_query {
    require CGI::Simple;
    CGI::Simple->new();
}

sub cgiapp_init {
    my $self     = shift;
    my $dataname = "data.dbm";
    my %database;
    die("Can't open ${dataname}: $!\n")
      unless dbmopen %database, $dataname, 438;
    $$self{'DATA'} = \%database;
}

sub start {
    my $self         = shift;
    my $templatename = 'start.tt';
    my %database     = %{ $$self->{'DATA'}; };
    my $posts        = $database{'POSTS'};
    my $vars         = { 'posts', $posts };
    return $self->tt_process( $templatename, $vars );
}

sub new_post_form {
    my $self         = shift;
    my $templatename = 'new_post_form.tt';
    return $self->tt_process($templatename);
}

sub new_post_success {
    my $self         = shift;
    my $templatename = "new_post_success.tt";
    my (%database) = %{ $$self->{'DATA'}; };
    my @posts = ();
    my $post;
    if ( defined $database{'POSTS'} ) {
        @posts = @{ $database{'POSTS'}; };
    }
    my $query   = $self->query;
    my $title   = $self->param('title');
    my $content = $self->param('content');
    $post = {
        title   => $title,
        content => $content
    };
    my $vars = {
        title   => $title,
        content => $content
    };
    push @posts, $post;
    $database{'POSTS'} = \@posts;
    return $self->tt_process( $templatename, $vars );
}
1;

    [download]
[reply]
[d/l]
      Error executing run mode 'start': Not a SCALAR reference at Bloggie.pm line 40. at /var/www/Bloggie.pl line 7 ^ that's what CGI::Carp gives me.
[reply]
        I wonder whether line 40 might be this one, in "sub start...": 
            my %database     = %{ $$self->{'DATA'}; };

        [download]
        If so, you should try "$self" instead of "$$self" there. The extra "$" was probably a mistake. (The extra semi-colon, immediately following {'DATA'}, might also be a mistake, which might show up as such when you fix the sigil problem...)
[reply]
[d/l]
[select]
      Can someone please help? It just isn't working!
[reply]

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