Parsing cgi variable lists

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

I use Mason for my websites, so I don't usually run into the issue of getting variables. However, I need to dynamically get my variables (so I don't have to initialize each one).

<form method="get" action="test_list.html">
<input type="hidden" name="LineItem" value="1" />
First Number: <input type="text" name="first-1" /><br />
Second: <input type="text" name="second-1" /><br />
Third: <input type="text" name="third-1" />
</p>

<p>
<input type="hidden" name="LineItem" value="2" />
First Number: <input type="text" name="first-2" /><br />
Second: <input type="text" name="second-2" /><br />
Third: <input type="text" name="third-2" />
</p>

<input type="submit" name="a" value="go">
</form>
[download]

From a form like that I need to keep the components together that end in the same number so I can do something with it from the database. I found a mailing list post that suggested the following, but I kept getting an error from it:

foreach (values $ARGS{LineItem}) {
    $SQL->execute(
        $PONum,
        $ARGS{"first-${i}"},
        $ARGS{"second-${i}"},
        $ARGS{"third-${i}"}
    );
}
[download]

I tried a few things but my main problem was getting the LineItem variable into an array (not an array of arrays). So it only gets one of the sets of variables.

my @lineitems = $ARGS{"LineItem"};
foreach my $line (@lineitems) {
print "line is @$line[0]";
print $ARGS{"first-@$line[0]"};
print $ARGS{"second-@$line[0]"};
print $ARGS{"third-@$line[0]"};

}
[download]

I am guessing I am getting CLOSE, but I can't quite complete it without some help. Thanks!

Michael Jensen
inblosam.com

Comment on Parsing cgi variable lists Select or Download Code

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Re: Parsing cgi variable lists by tlm (Prior) on Jun 29, 2005 at 13:19 UTC
What errors are you getting? I don't know the first thing about Mason, but this bit `values $ARGS{LineItem}` [download] looks wrong, because the argument to the `values` builtin should be a hash, and `$ARGS{ LineItem }` is a scalar. Maybe you want something like this? `values %{ $ARGS{ LineItem } }` [download] Likewise, I suspect this `my @lineitems = $ARGS{"LineItem"};` [download] is not doing what you want (it creates an array of one item, which, in this case at least, would not warrant iterating over with a `foreach` loop). Maybe you want `my @lineitems = @{ $ARGS{ LineItem } }` [download] but both this and my earlier suggestion can't both be right (Perl doesn't permit something that is a reference to both an array and a hash). There are other basic syntax errors in your code, which suggests to me that reading `perldata`, `perlreftut`, and `perlref` would be useful to you. Otherwise I think you will be "programming by trial and error", which is not only painful but dangerous, because your only indication of success is when the thing "runs" and terminates normally. A program can easily pass this test and still be completely wrong. Also, from your code it is not clear to me what `$i` (i.e. `${i}`) is. the lowliest monk	[reply] [d/l] [select]
Re: Parsing cgi variable lists by fmerges (Chaplain) on Jun 29, 2005 at 13:50 UTC
Hi, Try this: `for my $i (@$ARGS{LineItem}) { $SQL->execute( $PONum, $ARGS{"first-${i}"}, $ARGS{"second-${i}"}, $ARGS{"third-${i}"} }` [download] $ARGS{LineItem} is a Reference to an Array, so you first need to dereference it. Take a look at http://www.masonbook.com/book/chapter-2.mhtml#TOC-ANCHOR-11 Regards, \|fire\|	[reply] [d/l]
Re: Parsing cgi variable lists by tcf03 (Deacon) on Jun 29, 2005 at 13:21 UTC
`foreach (values $ARGS{LineItem}) { $SQL->execute( $PONum, $ARGS{"first-${i}"}, $ARGS{"second-${i}"}, $ARGS{"third-${i}"} ); }` [download] Where is $i coming from shouldn't you be using `foreach my $i (values $ARGS{LineItem})` I may be missing something though. Ted -- "That which we persist in doing becomes easier, not that the task itself has become easier, but that our ability to perform it has improved." --Ralph Waldo Emerson	[reply] [d/l] [select]
Re: Parsing cgi variable lists by inblosam (Monk) on Jun 29, 2005 at 14:51 UTC
Okay, I tried an above suggestion and this worked out: `my @lineitems = @{ $ARGS{ LineItem } }; foreach my $line (@lineitems) { print "line is $line"; my $first = $ARGS{"first-$line"}; my $second = $ARGS{"second-$line"}; my $third = $ARGS{"third-$line"}; print "first is $first"; print "second is $second"; print "third is $third"; }` [download] This appears to be working now. Thanks for the help! Michael Jensen	[reply] [d/l]
Re^2: Parsing cgi variable lists by davidrw (Prior) on Jun 29, 2005 at 15:37 UTC
In the future (and in general cases where data structure isn't known), a simple `use Data::Dumper; warn Dumper \%ARGS; warn Dumper $ARGS{LineItem};` [download] would have show that it was an array ref, leading immediately to the `@{$ARGS{LineItem}}` solution. Also, in mason you can do this: `<%args> $LineItem=>[] </%args> <%init> warn join ":", @$LineItem; ... </%init>` [download] That takes care of the case where just one LineItem form element exists. Using that syntax, you'll still get an array ref. Using the above $ARGS{LineItem} syntax you'll get a scalar, which will make the `@{$ARGS{LineItem}}` solution error out.	[reply] [d/l] [select]
Re: Parsing cgi variable lists by inblosam (Monk) on Jun 29, 2005 at 13:32 UTC
I wasn't sure about the code from the mailing list either (like where did the $i come from etc) but I thought I would post it because it seems to be a decent attempt. The error I was getting with the mailing list code (beside not initializing the $i) was "Type of arg 1 to values must be hash (not hash element)". I will give it a try with your suggestions, but any more are welcome for the optimum way to do this. Thanks! Michael Jensen	[reply]