Recently in Snippet Category

Figuring this out was somewhat painful, so I thought I would blog it.

I want to use the same form yaml for several different actions (update, create, view) andI had a list of field names I wanted to remove that were not relevant for create.

The remove_element method only works on the immediate children of the invoking object (as does get element), so $form->remove_element does not usually work.  I found a posting on the HTML::FormFu list where Carl Franks showed the idiom $element->parent->remove_element($element);

So my code became:

# remove fields not needed for this action
for (qw(created_by created_time changed_by changed_time version)) {
	my $element = $form->get_all_element({name => $_});
	if ($element) {
		$element->parent->remove_element($element);
	}
}


Works great!

Here is a quick script I wrote to load SQLite tables from CSV files.  I exported the files from Microsoft Access.  The first row has to have correct column names.

Text::xSV is the best CSV file handler I could find on CPAN.  It correctly handles files with embedded newlines as well as very large files.  SQL::Abstract makes it very easy to use straight DBI to speed up the load without going through an ORM. 

I prepare each row separately because I may have cases where there are trailing unused fields, and some Microsoft programs (Outlook comes to mind) do not attempt to output empty fields for them.  If the speed difference is important, you may want to try to guarantee the exact number of fields in each row so you can prepare once.

#!/usr/bin/perl

# load_csv.pl - Load a db table from a csv file.
#               First row must be field names.
# 04/28/2009  W. Ruppert

use strict;
use warnings;
use Text::xSV;
use DBI;
use SQL::Abstract;

$| = 1;

sub usage {
    my ($msg) = @_;
    warn "$msg\n" if $msg;
    die "Usage: load_csv.pl db table csvfile\n";
}

# get parms
my $db        = shift || usage "No database name";
my $table     = shift || usage "No table name";
my $data_file = shift || usage "No csv data file";

usage "No such file: $db"        unless -e $db;
usage "No such file: $data_file" unless -e $data_file;

# setup csv file
my $csv = new Text::xSV;
$csv->open_file("$data_file");
$csv->read_header();

my $sql = SQL::Abstract->new;

# connect to db
my $dbh = DBI->connect("dbi:SQLite:$db", "","",
        { RaiseError => 1, PrintError => 0 }
) or die "can't connect\n";

$dbh->do('begin');

my $max_commit  = 1000;
my $inserted    = 0;

# process csv rows
while (my %fieldvals = $csv->fetchrow_hash) {

    # SQL::Abstract sets up the DBI variables
    my($stmt, @bind) = $sql->insert($table, \%fieldvals);

    # insert the row
    my $sth = $dbh->prepare($stmt);
    $inserted += $sth->execute(@bind);

    # progress bar
    print "*"            unless $inserted % 10;
    print " $inserted\n" unless $inserted % 500;

    # commit every once in a while
    unless ($inserted % $max_commit) {
        $dbh->do('commit');
        $dbh->do('begin');
    }
}

$dbh->do('commit');
$dbh->disconnect;

print "\nInserted $inserted records\n";
exit 1;

Need to get the size of an image on the web without storing it.  Done by pulling the image with LWP::Simple and giving the content buffer to Image::Size.

#!/usr/bin/perl
# Get dimensions of web image
# 04/17/2009  WR

use strict;
use warnings;
use LWP::Simple;
use Image::Size;

my @urls = (
	"http://www.google.com/intl/en_ALL/images/logo.gif",
	"http://l.yimg.com/a/i/ww/beta/y3.gif",
	"http://www.example.com/nothing.gif",
	"http://graphics8.nytimes.com/images/misc/nytlogo379x64.gif",
);

URL:
for my $url (@urls) {
	my $image = get $url;
	unless (defined $image) {
		warn "Couldn't get $url!\n";
		next URL;
	}
	my ($width, $height) = imgsize(\$image);
	printf "%4d %4d   %s\n", $width, $height, $url;
}

exit 1;