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POPerl: variable scope issue with CGI & DBI modules
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copied!<p>I've run into what appears to be a variable scope issue I haven't encountered before. I'm using Perl's CGI module and a call to DBI's do() method. Here's the code structure, simplified a bit:</p> <pre><code>use DBI; use CGI qw(:cgi-lib); &ReadParse; my $dbh = DBI->connect(...............); my $test = $in{test}; $dbh->do(qq{INSERT INTO events VALUES (?,?,?)},undef,$in{test},"$in{test}",$test); </code></pre> <p>The #1 placeholder variable evaluates as if it is uninitialized. The other two placeholder variables work.</p> <p><strong>The question: Why is the %in hash not available within the context of do(), unless I wrap it in double quotes (#2 placeholder) or reassign the value to a new variable (#3 placeholder)?</strong></p> <p>I think it's something to do with how the CGI module's ReadParse() function assigns scope to the %in hash, but I don't know Perl scoping well enough to understand why %in is available at the top level but not from within my do() statement.</p> <p>If someone does understand the scoping issue, is there a better way to handle it? Wrapping all the %in references in double quotes seems a little messy. Creating new variables for each query parameter isn't realistic.</p> <p>Just to be clear, my question is about the variable scoping issue. I realize that ReadParse() isn't the recommended method to grab query params with CGI.</p> <p>I'm using Perl 5.8.8, CGI 3.20, and DBI 1.52. Thank you in advance to anyone reading this.</p> <p>@Pi & @Bob, thanks for the suggestions. Pre-declaring the scope for %in has no effect (and I always use strict). The result is the same as before: in the db, col1 is null while cols 2 & 3 are set to the expected value.</p> <p>For reference, here's the ReadParse function (see below). It's a standard function that's part of CGI.pm. The way I understand it, I'm not meant to initialize the %in hash (other than satisfying strict) for purposes of setting scope, since the function appears to me to handle that:</p> <pre><code>sub ReadParse { local(*in); if (@_) { *in = $_[0]; } else { my $pkg = caller(); *in=*{"${pkg}::in"}; } tie(%in,CGI); return scalar(keys %in); } </code></pre> <p>I guess my question is what is the best way to get the %in hash within the context of do()? Thanks again! I hope this is the right way to provide additional info to my original question.</p> <p>@Dan: I hear ya regarding the &ReadParse syntax. I'd normally use CGI::ReadParse() but in this case I thought it was best to stick to how <a href="http://search.cpan.org/src/LDS/CGI.pm-3.42/cgi-lib_porting.html" rel="nofollow noreferrer">the CGI.pm documentation has it</a> exactly.</p>

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