Formatting Lists and Tables with HTML Shortcuts (Perl Cookbook, 2nd Edition)

19.6.3. Discussion

The HTML-generating functions in CGI.pm can make it easy to generate lists and tables. Passed a simple string, these functions produce HTML for that string. But passed an array reference, they work on all strings in that array.

print li("alpha");
<LI>alpha</LI>
print li( [ "alpha", "omega"] ); 
<LI>alpha</LI> <LI>omega</LI>

The shortcut functions for lists are loaded when you use the :standard import tag, but you need to ask for :html3 explicitly to get helper functions for tables. There's also a conflict between the <TR> tag, which would normally make a tr( ) function, and Perl's built-in tr/// operator. Therefore, to make a table row, use the Tr( ) function.

This example generates an HTML table starting with a hash of arrays. The keys will be the row headers, and the array of values are the columns.

use CGI qw(:standard :html3);

%hash = (
    "Wisconsin"  => [ "Superior", "Lake Geneva", "Madison" ],
    "Colorado"   => [ "Denver", "Fort Collins", "Boulder" ],
    "Texas"      => [ "Plano", "Austin", "Fort Stockton" ],
    "California" => [ "Sebastopol", "Santa Rosa", "Berkeley" ],
);

$\ = "\n";

print "<TABLE><CAPTION>Cities I Have Known</CAPTION>";
print Tr(th [qw(State Cities)]);
for $k (sort keys %hash) {
    print Tr(th($k), td( [ sort @{$hash{$k}} ] ));
}
print "</TABLE>";

That generates text like this:

<TABLE> <CAPTION>Cities I Have Known</CAPTION>
    <TR><TH>State</TH> <TH>Cities</TH></TR>
    <TR><TH>California</TH> <TD>Berkeley</TD> <TD>Santa Rosa</TD> 
        <TD>Sebastopol</TD> </TR>
    <TR><TH>Colorado</TH> <TD>Boulder</TD> <TD>Denver</TD>
        <TD>Fort Collins</TD> </TR>
    <TR><TH>Texas</TH> <TD>Austin</TD> <TD>Fort Stockton</TD> 
        <TD>Plano</TD> </TR>
    <TR><TH>Wisconsin</TH> <TD>Lake Geneva</TD> <TD>Madison</TD> 
        <TD>Superior</TD></TR>
</TABLE>

You can produce the same output using one print statement, although it is slightly trickier because you have to use a map to create the implicit loop. This print statement produces output identical to that displayed previously:

print table
        caption('Cities I have Known'),
        Tr(th [qw(State Cities)]),
        map { Tr(th($_), td( [ sort @{$hash{$_}} ] )) } sort keys %hash;

This is especially useful for formatting the results of a database query, as in Example 19-3 (see Chapter 14 for more on databases).

Example 19-3. salcheck

  #!/usr/bin/perl
  # salcheck - check for salaries
  use DBI;
  use strict;
  use CGI qw(:standard :html3);
  
  my $limit = param("LIMIT");
  
  print header( ), start_html("Salary Query"),
        h1("Search"),
        start_form( ),
        p("Enter minimum salary", textfield("LIMIT")),
        submit( ),
        end_form( );
  
  if (defined $limit) {
      my $dbh = DBI->connect("dbi:mysql:somedb:server.host.dom:3306", 
          "username", "password") 
          or die "Connecting: $DBI::errstr";
      my $sth = $dbh->prepare("SELECT name,salary FROM employees 
          WHERE salary > $limit")
          or die "Preparing: ", $dbh->errstr;
      $sth->execute
          or die "Executing: ", $sth->errstr;
  
      print h1("Results"), "<TABLE BORDER=1>";
  
      while (my $row = $sth->fetchrow_arrayref( )) {
             print Tr( td( $row ) );
      }
  
      print "</TABLE>\n";
      $sth->finish;
      $dbh->disconnect;
  }
  
  print end_html( );

Example 19-3. salcheck

19.6. Formatting Lists and Tables with HTML Shortcuts

19.6.1. Problem

19.6.2. Solution

19.6.3. Discussion

19.6.4. See Also