comment on

Dear Monks,

Below is a simple cgi script I wrote to display different messages based on the value for $item using HTML Template

Everything worked fine and I didn't think about raising this question here until I read the following from HTML::Template Documentation

WARNING: Much of the benefit of HTML::Template is in decoupling your Perl and HTML. If you introduce numerous cases where you have TMPL_IFs and matching Perl if()s, you will create a maintenance problem in keeping the two synchronized. I suggest you adopt the practice of only using TMPL_IF if you can do so without requiring a matching if() in your Perl code.

Below is the script and template:-

use CGI qw/:standard :delete_all :escapeHTML :html3 :all/;
use HTML::Template; 

print header; 

my $item = "CONTINUE";

my ($item1_val, $item2_val, $item3_val ) = 0;

if ($item eq "SELECT") {
    $item1_val = 1;
}
elsif ($item eq "CONTINUE") {
    $item2_val = 1;
}
elsif ($item eq "DENIED"){
    $item3_val = 1;
}

my $template = HTML::Template->new( filename => 'template4.tmpl' ); 

$template->param( item1 => $item1_val );
$template->param( item2 => $item2_val );
$template->param( item3 => $item3_val );

print $template->output();
[download]

Template:-

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>HTML::Template example</title>
</head>

<body>


<TMPL_IF name = "item1">
<table align="center">
<tr><td align="center">
<font style="font-size: 14pt; font-family: Arial; solid #CCC; padding:
+ 3px" color="blue">
<p>Please Select  an Item</p></font>
</td></tr>
</table>
</TMPL_IF>

<TMPL_IF name = "item2">
<table align="center">
<tr><td align="center">
<font style="font-size: 14pt; font-family: Arial; solid #CCC; padding:
+ 3px" color="blue">
<p>Item Selected: Car</p></font>
</td></tr> 
<tr><td align="center">
<font style="font-size: 8pt; font-family: Arial; solid #CCC; padding: 
+3px" color="black">
<p>(Please click to continue)</p></font>
</td></tr> 
<tr><td align="center">
<input type="button" value="submit"/>
</td></tr>
</table>
</TMPL_IF>

<TMPL_IF name = "item3">
<table align="center">
<tr><td align="center">
<font style="font-size: 14pt; font-family: Arial; solid #CCC; padding:
+ 3px" color="blue">
<p>Item Selected: Mini Van</p></font>
</td></tr> 
<tr><td align="center">
<font style="font-size: 12pt; font-family: Arial; solid #CCC; padding:
+ 3px" color="red">
<b>Access to this Item is denied</b></font>
</td></tr> 
</table>
</TMPL_IF>

</body>
</html>
[download]

As you can see, I end up in a situation, where I have matching 'if' and 'TMPL_IF' loops in the perlscript and template, respectively

The other way I could think is to have a variable (say $html_output) in the script and use the cgi module to append the appropriate html code to the variable and finally display that using HTML::Template as follows:-

use CGI qw/:standard :delete_all :escapeHTML :html3 :all/;
use HTML::Template; 

print header; 

my $item = "CONTINUE";

if ($item eq "SELECT") {
   $html_output = ......
}
elsif ($item eq "CONTINUE") {
   $html_output = ......
}
elsif ($item eq "DENIED"){
   $html_output = ......
}

my $template = HTML::Template->new( filename => 'template4.tmpl' ); 

$template->param( html_output => $html_output );

print $template->output();
[download]

corresponding template...

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>HTML::Template example</title>
</head>

<body>

<TMPL_VAR name = "html_output">

</body>
</html>
[download]

In the above approach,I would be mixing scripts and html tags, which I hate to do.

Would you please suggest some ideas to handle this?

In reply to HTML::Template : How to separate code and html with lesser maintenance issues by sara2005

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