Perl Cd Bookshelf [Electronic resources] نسخه متنی

19.6. Formatting Lists and Tables with HTML Shortcuts

19.6.1. Problem

You have
several lists and tables to generate and wish they were easier to
output.

19.6.2. Solution

The CGI module provides HTML helper functions that, when passed array
references, apply themselves to each element of the referenced
array:

print ol( li([ qw(red blue green)]) );
<OL><LI>red</LI><LI>blue</LI><LI>green</LI></OL>
@names = qw(Larry Moe Curly);
print ul( li({ -TYPE => "disc" }, \@names) );
<UL><LI TYPE="disc">Larry</LI> <LI TYPE="disc">Moe</LI>
    <LI TYPE="disc">Curly</LI></UL>

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( );

19.6.4. See Also

The documentation for the standard CGI module; Recipe 14.9