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File handling? How to make the better one?

by heatblazer (Scribe)
on Jun 11, 2012 at 14:01 UTC ( #975568=perlquestion: print w/ replies, xml ) Need Help??
heatblazer has asked for the wisdom of the Perl Monks concerning the following question:

Hello again!

I`ve actually managed to crete my serverside perl script for creating and/or overwriting an existing json file for my JSONP script. But my perl script is kinda weird. I had to open file 2 times, truncate it and the process looks not reliable... or it`s ok...

I need a quick review and an info if the script is good to go or it must undergo some maintenance.

#!/opt/lampp/bin/perl use strict; use CGI; ##### S U B S ######### sub speaker { my $text = shift; print "Content-type: text/html\n\n"; print $text; } sub makeJSON { #create and record a JSON file my ( $name, $mail, $pass ) = @_; if ( system("ls -l | grep datafile.json") == 0 ) { my $replace_me =""; #the storage for replace; my $jobj = "\n \t\t{ \"name\":\t\"$name\",\n\t\t\"mail\":\t\"$ +mail\",\n\t\t\"pass\":\t\"$pass\",\n\t\t },\n];"; open (FH, "</opt/lampp/htdocs/datafile.json") or die("can`t op +en filehandle: $!\n"); while ( <FH> ) { if ( /\]/ ) { $replace_me .= $jobj; } else { $replace_me .= $_; } } close(FH); #truncate and create again open (FR, ">/opt/lampp/htdocs/datafile.json") or die("can`t op +en filehandle: $!\n"); print FR $replace_me; close(FR); } else { my $jobj = "var user = [ \n\t\t{ \"name\":\t\"$name\",\n\t\t\" +mail\":\t\"$mail\",\n\t\t\"pass\":\t\"$pass\",\n\t\t },\n];"; open (FH, ">/opt/lampp/htdocs/datafile.json") or die("can`t op +en filehandle: $!\n"); print FH $jobj; close(FH); } print "Content-type: text/html\n\n"; print "<p>Finished file</p>"; } ################################################## my $q = CGI->new(); my ($name, $mail, $pass) = ( $q->param('name'), $q->param('mail'), $q->param('pass'), ); makeJSON($name, $mail, $pass);

THanks in advance

Comment on File handling? How to make the better one?
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Re: File handling? How to make the better one?
by tobyink (Abbot) on Jun 11, 2012 at 15:08 UTC
    if ( system("ls -l | grep datafile.json") == 0 ) {

    Sweet Jesus! Is this you trying to check whether a file exists?! You know Perl does have built-ins for checking the existence of a file...

    if (-f "datafile.json") {

    Using a few commodity modules from CPAN, you can make your life a lot easier...

    #!/opt/lampp/bin/perl use strict; use CGI; use CGI::Carp 'fatalsToBrowser'; use File::Slurp qw< read_file write_file >; use JSON qw< from_json to_json >; use constant USER_ACCOUNT_FILE => '/opt/lampp/htdocs/datafile.json'; sub store_user_account { my ($name, $mail, $pass) = @_; my $existing_data = -f USER_ACCOUNT_FILE ? from_json(scalar read_file(USER_ACCOUNT_FILE, err_mode => 'c +roak')) : []; push @$existing_data, { name => $name, mail => $mail, pass => $pass, }; write_file( USER_ACCOUNT_FILE, { atomic => 1, err_mode => 'croak' }, to_json($existing_data), ); } sub process_cgi { my ($q) = @_; store_user_account( map { scalar $q->param($_) } qw(name mail pass), ); print $q->header('text/html'); print "<p>Finished file.</p>\n"; } process_cgi( CGI->new );
    perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

      Thanks, I don`t know all these tricks. I`ll most definitely look upon that JSON module too. Looks like it will make my life better.

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