changing DB delimiters

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

Could anyone tell me what in this script separates the
records by a newline character? I am wanting to change
this to separate the entries/records with my own character, and not "\n". This script modifies records found in a flat-file database THANKS

#!/usr/local/bin/perl-w
use strict;
use CGI;

my $query =new CGI;

my $guest_file = "new_guestbook.html";

&print_page_start;

if ($query->param()) {
    if ($query->param('new_name')) {
    if (&valid_form) {

        eval {
        open (GUESTS, "+>> $guest_file") or
              die "Can't open $guest_file: $!";
        flock GUESTS, 2;
        seek GUESTS, 0, 0;
        my @guests = <GUESTS>;
        my @new_guests = ();

        foreach $guest (@guests) {
             chomp $guest;
             ($name, $email, $comments) = split /::/, $guest;
             if ($name eq $query->param('name') &&
             $email eq $query->param('email') &&
             $comments eq $query->param('comments')) {
             $name = $query->param('new_name');
             $email = $query->param('new_email');
             $comments = $query->param('new_comments');
             $guest = "$name::$email::$comments";
             }
             $guest .= "\n";
             push @new_guests, $guest;
       }
       seek GUESTS, 0,0;
       truncate GUESTS, 0;
       print GUESTS @new_guests;
       close GUESTS;

       print "<P>Record(s) modified.</P>\n";
       print "<A HREF=\"retrieve.pl\">Retrieve records.</A>\n";
       }
}
else {
      &print_form;
}
}
else {
&print_form;
}
}
else {
      &print_record_list;
}

chomp $@;
if ($@) {
   print "ERROR: $@<BR>\n";
}

&print_page_end;

sub print_page_start {
      print $query->header;
      print "<HTML>\n<HEAD>\n<TITLE>Modify Records</TITLE>\n";
      print "</HEAD>\n<BODY>\n";
      print "<H1>Modify Records</H1>\n";
}

sub print_form {
      print "<P>\n<FORM>\n";
      if (!$query->param()) {
      print "Name: <INPUT TYPE=\"text\" NAME=\"new_name\"><BR>\n";
      print "Email: <INPUT TYPE=\"text\" NAME=\"new_email\"><BR>\n";
      print "Comments: <INPUT TYPE=\"text\" NAME=\"new_comments\"><BR>
+\n";
      print "VALUE=\"$comments\">$comments<BR>\n";
      }
      
      else {
           if ($query->param('new_name')) {
           print "Name: <INPUT TYPE=\"text\" NAME=\"new_name\" ";
           print "VALUE=\"", $query->param('new_name'), "\"><BR>\n";
           print "Email: <INPUT TYPE=\"text\" NAME=\"new_email\" ";
           print "VALUE=\"", $query->param('new_email'), "\"><BR>\n";
           print "Comments: <INPUT TYPE=\"text\" NAME=\"new_comments\"
+ ";
           print "VALUE=\"", $query->param('new_comments'), "\"><BR>\n
+";
           }
      
      else {
           print "Name: <INPUT TYPE=\"text\" NAME=\"new_name\" ";
           print "VALUE=\"", $query->param('name'), "\"><BR>\n";
           print "Email: <INPUT TYPE=\"text\" NAME=\"new_email\" ";
           print "VALUE=\"", $query->param('email'), "\"><BR>\n";
           print "Comments: <INPUT TYPE=\"text\" NAME=\"new_comments\"
+ ";
           print "VALUE=\"", $query->param('comments'), "\"><BR>\n";
           }
      }
      }
      print "<INPUT TYPE=\"hidden\" NAME=\"name\" ";
      print "VALUE=\"" . $query->param('name') . "\">\n";
      print "<INPUT TYPE=\"hidden\" NAME=\"email\" ";
      print "VALUE=\"" . $query->param('email') . "\">\n";
      print "<INPUT TYPE=\"hidden\" NAME=\"comments\" ";
      print "VALUE=\"" . $query->param('comments') . "\">\n";
      print "</FORM>\n</P>\n";


sub valid_form {
      $return_code = 1;
      if (!$query->param('new_name')) {
      print "You must enter a name.<BR>\n";
      $return_code = 0;
      }
      if (!$query->param('new_email')) {
      print "You must enter an email address.<BR>\n";
      $return_code = 0;
      }
   
      if (!$query->param('comments')) {
      print "You must enter some comments.<BR>\n";
      $return_code =0;
      }
  return $return_code;


sub print_record_list {
      open (GUESTS, "< $guest_file") or
      die "Can't open guest file: $!";
      while (<GUESTS>) {
      chomp;
      ($name, $email, $comments) = split /::/;
      print "<P>\n";
      print "<FORM>\n";
      print "Name: $name<BR>\n";
      print "Email: $email<BR>\n";
      print "Comments: $comments<BR>\n";
      print "<INPUT TYPE=\"hidden\" NAME=\"name\" VALUE=\"$name\">\n";
      print "<INPUT TYPE=\"hidden\" NAME=\"email\" VALUE=\"$email\">\n
+";
      print "<INPUT TYPE=\"hidden\" NAME=\"comments\" VALUE=\"$comment
+s\">\n";
      print "<INPUT TYPE=\"submit\" VALUE=\"Edit this entry\">\n";
      print "</FORM>\n";
      print "</P>\n";
      }
}

sub print_page_end {
      print "</BODY>\n</HTML>\n";
}

}
[download]

Comment on changing DB delimiters Download Code

Replies are listed 'Best First'.
Re: changing DB delimiters by azatoth (Curate) on Jun 20, 2001 at 10:28 UTC
`$guest .= "\n";` [download] FYI, the `.=` assignment operator is a shortcut for concatenating the value of `$guest` with `"\n"`. To wit, a quicker way of writing `$new_guest = $guest . "\n";` Next! Azatoth a.k.a Captain Whiplash Make Your Die Messages Full of Wisdom! Get YOUR PerlMonks Stagename here! Want to speak like a Londoner?	[reply] [d/l] [select]
Re: changing DB delimiters by jeroenes (Priest) on Jun 20, 2001 at 11:19 UTC
You can choose them yourself. See perlvar. `local $/ = "vroom"; #$/ is input separator. From now on, # script will split lines on 'vroom' local $, = "PM!PM!" #$, is print rec separator. From now on, # script will print 'PM!PM!' between items of arr +ay` [download] Jeroen "We are not alone"(FZ)	[reply] [d/l]
Re: changing DB delimiters by Abigail (Deacon) on Jun 20, 2001 at 20:35 UTC
Actually, `$,` would be the field separator, while `$\` is the record separator. If you want it to work for the given code, you'd need to do: `local $/ = local $\ = local $, = "\n";` [download] or else the last record isn't properly terminated. -- Abigail	[reply] [d/l] [select]
Re:{2} Output Separators (Was: changing DB delimiters) by jeroenes (Priest) on Jun 20, 2001 at 20:50 UTC
Well, it depends on what you do, actually. I understand that he prints his 'DB' with `print @guests`. In that case, you need to separate the fields with `$,`. The `$\` is active after each print statement, as appears from: $OUTPUT_FIELD_SEPARATOR $OFS $, The output field separator for the print operator. Ordinarily the print operator simply prints out its arguments without further adornment. To get behavior more like awk, set this variable as you would set awk's OFS variable to specify what is printed between fields. (Mnemonic: what is printed when there is a "," in your print statement.) $OUTPUT_RECORD_SEPARATOR $ORS $\ The output record separator for the print operator. Ordinarily the print operator simply prints out its arguments as is, with no trailing newline or other end-of-record string added. To get behavior more like awk, set this variable as you would set awk's ORS variable to specify what is printed at the end of the print. (Mnemonic: you set `$\' instead of adding "\n" at the end of the print. Also, it's just like `$/', but it's what you get "back" from Perl.) So it makes no sense to set `$,` and `$\` to the same value. Jeroen	[reply] [d/l] [select]
Re: Output Separators (Was: changing DB delimiters) by Abigail (Deacon) on Jun 20, 2001 at 22:27 UTC
Re:{4} Output Separators (Was: changing DB delimiters) by jeroenes (Priest) on Jun 21, 2001 at 01:26 UTC
Some notes below your chosen depth have not been shown here
Re: changing DB delimiters by Abigail (Deacon) on Jun 20, 2001 at 20:31 UTC
It looks quite obvious to me what makes the record separator. You are writing records called `$guest` to a file, and you append newlines to `$guest` just before storing it. Where else would you expect this to happen? Now that you have posted all this code (of which most is completely pointless - if you have a question about your database, don't post dozens of lines of HTML generation, it makes it much harder to figure out what's going on), why are you opening the file `new_guestbook.html` for append if you truncate it to 0 bytes before prints? And why aren't you checking the return value of `flock`? What if the `flock` fails? You should also realize that reading in the entire database and writing it out again is ineffecient. Why not just use a dbm file? -- Abigail	[reply] [d/l] [select]
Re: changing DB delimiters by thabenksta (Pilgrim) on Jun 21, 2001 at 18:28 UTC
The Database is separated on the `\n` when you say `my @guests = <GUESTS>;`. When you assign a filehandle to an array, it automatically splits on `\n`. I'm not sure how to change this, but I assume that jeroenes is right. But I do know you can use `split`. `my @guests = split(/delimiter/, <GUESTS>);` hope that helps -thabenksta `my $name = 'Ben Kittrell'; $name=~s/^(.+)\s(.).+$/\L$1$2/g; my $nick = 'tha' . $name . 'sta';` [download]	[reply] [d/l] [select]
Re: Re: changing DB delimiters by Anonymous Monk on Jun 21, 2001 at 21:07 UTC
Thank you so much Thabenksta, you and jeroenes are the ones that addressed the problem most effectively. I agree with you in that I'm wanting to write code to get around this kind of "default" setting of splitting records on the newline character.......although I'm still testing code to accomplish this.	[reply]