Perl CGI - How can I delete contents of text fields? - perl

Question

So, I am totally new with CGI programming in Perl.
The question is simple. Is there any chance to delete the content of a text field in CGI?
I must to write a code that have some popup_menu, submit button and text fields (area).
When I click on the submit button the program reads the value from one of the popup_menu.
The task is to copy this content into text field and then when I choose another element from the popup_menu (and click on the submit button of course), let the new content write into the text field replace the old one.
I think perldoc.perl.org gives only a little information about CGI programming. I'd have lot of questions in thema... :(
Any help would be approciate!

Answer 1

I guess, what you describe is: when you click the submit button, then your cgi script will run, given the parameters you entered in the form. What I then has to do is: write something back and print the form again - with different values.
So even if this is not the perfect way of doing such kind of things (for simple form element substitution you should do it client side and use javascript - you don't need a cgi backend script for this), let's see how a cgi script might look like.
First it's important to know, how you write your form. Let's assume you write it "the hard way" with print.
What your script has to do is parse the input and then add it as a value to the output.
use CGI;
my $q = CGI->new;
# get the value from the popup / html select
my $popup_value = $q->param('popup_menu'); # name of the <select name="..."> in your html
# ...
# writing the form
print $q->header;
# some more prints with form etc.
print textarea( -name => 'text_area',
-default => $popup_value // '', # will use empty string on first call
);
# Don't turn off autoescaping !
BTW, the value of a select option is meant to be a short indicator, not a full text (even this might be possible up to a certain amount of characters). So you might think of building a hash or an array with the appropriate values to be printed in the text area and give your select options the values 0, 1, 2 ...
my #text_values = ('', 'First text', 'second text', 'third text');
my $popup_value = $q->param('popup_menu') || 0; # default index.
# now use 1,2,3, ... as values in your popup_menu options
# ...
print textarea( -name => 'text_area',
-default => $text_values[$popup_value] );