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

I am using the CGI module to write an html page. I'm using OO, so $q = new CGI; and $q->end_html prints the closing </body> and </html> tags fine. However, $q->start_html isn't printing the opening tags? Code below for the page and its associated 'view source'. Thanks. 

sub sectionOne() {
$q->header();
style ();
$q->start_html();
print "Enter the Number of Buildings:\n";
print "<form name=\"form1\" action=\"add_building_names.cgi\" method=\
+"POST\">\n";
print "<table style=\"border-collapse:separate;padding:0px;width:100px
+;font-size:8pt\">\n";
print "<tr>\n";
print "<td><input type=\"text\" name=\"num_buildings\" size=\"5\"></td
+>\n";
print "<td><input type=\"submit\" name=\"submit_num_buildings\" value=
+\"Update\"></td>\n";
print "</tr>\n";
print "<input type=\"hidden\" name=\"section_number\" value=\"2\">\n";
print "</form>\n";
print "</table>";
$q->end_html();
}

[download]


Here is the 'view source' 

<style type="text/css">
table {
      border:solid black 0px;
      padding:10px;
      border-collapse:separate;
      width:600px;
      }
td {
    border:solid black 1px;
    padding:5px;
    font-weight: bolder;
    text-align: center;
   }
</style>
Enter the Number of Buildings:
<form name="form1" action="add_building_names.cgi" method="POST">
<table style="border-collapse:separate;padding:0px;width:100px;font-si
+ze:8pt">
<tr>
<td><input type="text" name="num_buildings" size="5"></td>
<td><input type="submit" name="submit_num_buildings" value="Update"></
+td>
</tr>
<input type="hidden" name="section_number" value="2">
</form>
</table>
</body>
</html>

[download]

Replies are listed 'Best First'.
Re: CGI 'start_html' not printing opening <body> or <html>
by tilly (Archbishop) on Mar 04, 2009 at 23:10 UTC
    CGI just returns the text, it does not print it, so you have to print that for yourself. You also will need to print the header.

    If the end_html stuff is being printed, then I am guessing that whoever called the poorly named sectionOne function is printing what it returns, and end_html is what gets returned and therefore printed.

    As a random note, with most ways of organizing code, you are better off using a templating system and not using CGI's html generation methods. This is not a hard and fast rule, but it is a good guideline. See Re (tilly) 6: Code Critique for some general advice on templating.

[reply]
Re: CGI 'start_html' not printing opening <body> or <html>
by bellaire (Hermit) on Mar 04, 2009 at 23:10 UTC
    You need to print the return values of those calls. 
    print $q->header();
print $q->start_html();

    [download]
    The same should hold true for end_html, I'm not sure why view source shows that output for you, when I run your source from the command line, I don't see the closing body or html tags.
[reply]
[d/l]
Re: CGI 'start_html' not printing opening <body> or <html>
by cormanaz (Deacon) on Mar 04, 2009 at 23:14 UTC
    You'll have a better chance of getting a good answer if you post all the code. From this it's not clear how you're passing the CGI object $q to the sub. It's not an argument. Is it defined as a global? Also what's this style sub you're calling?
[reply]
      Below is the full code. I use the subroutines to print the HTML page based on the input required. The purpose of the page is to ask a user how many buildings are being worked on. I then reload the page, updating the section number to be the next section, and render the HTML pertinent to that section. The sub 'sectionTwo()' renders a table containing the number of input text boxes indicated in 'sectionOne()' by the user. The user enters the building names and proceeds to 'sectionThree()'. Section three shows a table that basically repeats the data input by the user and asks him/her to confirm that the data is correct prior to entering it into the database ('sectionFour()'). The sub 'style()' is simply a CSS sheet that gives me simple borders around my tables so I can see the layout. Once I get the forms working, I'll create a final CSS sheet and reference it in the 'start_html()'.
      Thanks.
      #!h:/xampp/perl/bin/perl -w

# PERL MODULES WE WILL BE USING
use DBI;
use DBD::mysql;
use CGI qw(:standard);
use CGI::Carp qw(warningsToBrowser fatalsToBrowser);
use dbConnect;

require "ap_messages_config.pl"; #PULL IN THE FILE THAT CREATES EACH H
+TML RESPONSE PAGE
                                  #INCLUDES THE SUB 'STYLE' FOR CSS
$q = new CGI;
print $q->header();
my @values = split(/=/,$ENV{QUERY_STRING});
my $customer_get = $values[1];
my $customer_post = $q->param('customer_post');
my $num_buildings = "";
my $errors = "";
my @parameters = $q->param(); #THIS JUST STORES THE NAMES OF THE PARAM
+ETERS. TO PRINT ITS VALUE, USE
                              #param($parameters[0]) . "<br>\n";

######################################################################
+###########################################
############################## BEGIN MAIN PROGRAM ####################
+###########################################
######################################################################
+###########################################
#style ();
print $q->start_html();
if (($q->param('section_number')) < 2) {

sectionOne($customer_get);
}
if (($q->param('section_number')) eq "2") {
sectionTwo();
}
if (($q->param('section_number')) eq "3") {
sectionThree($customer_post);
}
if (($q->param('section_number')) eq "4") {
sectionFour();
}
print $q->end_html();

######################################################################
+###########################################
############################## BEGIN MAIN PROGRAM ####################
+###########################################
######################################################################
+###########################################

############################################## SUBROUTINES ###########
+###########################################
=pod
sub javaScript() {
# USE CGI 'start_html' TO ADD JAVASCRIPT TO HEADER
print $q->start_html(
     -title=>'Enter AP Names',
     -script=> {
                -language => 'javascript',
                -src      => '../scripts/hideDiv.js'
               }
     );
style ();
}
=cut

################################## HTML PAGE TO ASK USER NUMBER OF BUI
+LDINGS #####################################
sub sectionOne() {
print "Section One.<br>\n";
print "The value of \$customer_get is: $customer_get.<br>\n";
print "The value of \$customer_post is: $customer_post.<br>\n";
print "Enter the Number of Buildings:\n";
print "<form name=\"form1\" action=\"add_building_names.cgi\" method=\
+"POST\">\n";
print "<table style=\"border-collapse:separate;padding:0px;width:100px
+;font-size:8pt\">\n";
print "<tr>\n";
print "<td><input type=\"text\" name=\"num_buildings\" size=\"5\"></td
+>\n";
print "<td><input type=\"submit\" name=\"submit_num_buildings\" value=
+\"Update\"></td>\n";
print "</tr>\n";
print "<input type=\"hidden\" name=\"section_number\" value=\"2\">\n";
print "<input type=\"hidden\" name=\"customer_post\" value=\"" . $_[0]
+ . "\">\n";
print "</form>\n";
print "</table>";
}

#print param('num_buildings') . "<br>\n"; #THIS WORKS
#print param($parameters[0]) . "<br>\n";  #THIS WORKS TOO.

################################### HTML PAGE TO RENDER INPUT BOXES FO
+R BUILDING NAMES ############################
sub sectionTwo() {
print "Section Two.<br>\n";
print "The value of \$customer_get is: $customer_get.<br>\n";
print "The value of \$customer_post is: $customer_post.<br>\n";
#print "The length of \@parameters is: $#parameters.\n";
print "<table>\n";
print "<form name=\"building_names\" method=\"POST\" action=\"add_buil
+ding_names.cgi\">\n";

my $num_buildings = $q->param('num_buildings');
for ($i=1; $i<=$num_buildings; $i++) {
print "<tr>\n";
print "<td>Building: " . $i . "</td>\n<td><input type=\"text\" name=\"
+building_" . $i . "\"></td>\n";
print "</tr>\n";
}
print "<tr>\n";
print "<td>";
print "<input type=\"submit\" name=\"submit_building_names\" value=\"U
+pdate\">\n";
print "</td>\n";
print "</tr>\n";
print "<input type=\"hidden\" name=\"section_number\" value=\"3\">\n";
print "</form>\n";
print "</table>\n";
}

###################################### PRINT AND CONFIRM BUILDING NAME
+S ########################################3
sub sectionThree() {
print "$_[0]<br>\n";
print "Section Three.<br>\n";
print "The value of \$customer_get is: $customer_get.<br>\n";
print "The value of \$customer_post is: $customer_post.<br>\n";
my $customer = $_[0];
print "The value of \$customer (passed in to sub) is: $customer.<br>\n
+";
#Store the building names to variables
for ($i = 0; $i<$#parameters; $i++) {
#print $q->param($parameters[$i]) . "<br>\n";
if (($parameters[$i]) =~ /^building/) {
     my @buildings = push (@buildings,($q->param($parameters[$i])));
     }
}

$j = scalar (@buildings);
my @building_nums;
for ($k = 1; $k<=$j; $k++) {
     push (@building_nums,$k);
     }

print "<form name=\"submit_bldg_names\" method=\"POST\" action=\"add_b
+uilding_names.cgi\">\n";
print "<table>\n";
print "<tr>\n";
print "<td>You entered the following building names.  If they are corr
+ect, select 
'Submit' to add them to the database for customer $customer</td>\n";
print "</tr>\n";
print "<tr>\n";
print "<td>";
print "<input type=\"submit\" name=\"add_bldgs_database\" value=\"Subm
+it\">";
print "</td>\n";
print "</tr>\n";
for ($i = 0; $i<=$#buildings; $i++) {
print "<tr>\n";
print "<td>";
print "Building $building_nums[$i]: $buildings[$i]";
print "<input type=\"hidden\" name=\"building_" . $i . "\" value=\"" .
+ $buildings[$i] . "\">";
print "</td>\n";
print "</tr>\n";
}
print "<input type=\"hidden\" name=\"section_number\" value=\"4\">\n";
print "</table>\n";
print "</form>";
}

######################## ADD BUILDING NAMES TO THE DATABASE TABLE ####
+####################################
sub sectionFour() {
}

######################################################################
+####################################

      [download]
[reply]
[d/l]
        Fixed it. Sloppy code in my 'style()' sub. I was making another call to $q-> new CGI; when I didn't need it. I removed the external subroutine all together and placed 'sub style()' in the main program. Works fine.
[reply]

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