Cannot update record in file with Dump module

[yesilikeit]

Hi experts,

I am new in Perl and DBI - I have been following book:

O'reilly - Programming Perl DBI - From the ...

I cannot deal with chapter:

2.5.1 The Perl Data:umper Module

I rewrote the code and I try to run it with my text-db xxx.txt :

$name="MyName";$location="MyLoc";$mapRef="MyRef";$type="MyType";$description="MyDesc";

My code:

#!/usr/bin/perl
use Data::Dumper;

$Data::Dumper::Indent = 0;
$Data::Dumper::Useqq = 1;

$Data::Dumper::Purity = 1;
	
die "Usage: updatemegadata <data file> <site name> <new map reference>\n"
unless @ARGV == 3;

my $megalithFile = $ARGV[0];
my $siteName = $ARGV[1];
my $siteMapRef = $ARGV[2];
my $tempFile = "tmp.$$";

open MEGADATA, "<$megalithFile" or die "Can't open $megalithFile: $!\n";

open TMPMEGADATA, ">$tempFile" or die "Can't open temporary file $tempFile: $!\n";

while ( <MEGADATA> ) {

	next unless m/\Q$siteName/;

	my $fields;
	eval $_;
	die if $@;

	my ( $name, $location, $mapref, $type, $description ) = @$fields;

	next unless $siteName eq $name;

	$fields = [ $name, $location, $siteMapRef, $type, $description ];

	$_ = Data::Dumper->new( [ $fields ], [ 'fields' ] )->Dump();
	$_ .= "\n";

} continue {
	print TMPMEGADATA $_ or die "Error writing $tempFile: $!\n";
}
close MEGADATA;

close TMPMEGADATA or die "Error closing $tempFile: $!\n";

unlink $megalithFile or die "Can't delete old $megalithFile: $!\n";

rename $tempFile, $megalithFile or die "Can't rename '$tempFile' to '$megalithFile': $!\n";
exit 0;

It gives no effects after:

perl myScript.pl xxx.txt MyName Lalala

Could you help me? Probably format of my file-db is wrong...

 

[goBoating]

First, I'm rather pedantic and tend to use explicit variables rather that playing with $_, except in very well defined and brief instances. And, drop some print statements in a few places to see what's working and what's not.

while ( my $line = <MEGADATA> ) {
	print "LINE: $line";
	next unless ($line =~ m/\Q$siteName/);

	my $fields;
	eval $line;  # Not sure what you're doing, here.
	die if $@;

	my ( $name, $location, $mapref, $type, $description ) = split /some delimiter/, $line;
	print "NAME: $name\n";
	unless ($name =~ /\w/) { die "Apparently don't have a name and we should.\n"; }

and so on....


'hope this helps

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