Not a HASH reference

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

I am getting following error in perl. "Not a HASH reference at tocsvfd.pl line 31". the code.Below is the code through where I am getting this error. How can I correct it? The last line of the code is line 32

my $src = dir("C:/Perl/pubmed/Prasuna/DM/Database/Drugbank/Split");

#Check files in folder
my @txt_files = $src->children;

for my $txt_file ( @txt_files ) {
    my $in = $txt_file->openr;
    my $parser = new XML::Simple;
    my $tree = $parser->XMLin($in);

    $alldrug = $tree->{drug};
    #print pp($alldrug);
    @allkeys = keys % $alldrug;
[download]

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Re: Not a HASH reference by kennethk (Abbot) on Mar 22, 2017 at 16:43 UTC
Assuming line 31 is as you say, this means `$alldrug` does not contain hashref. If we trace that back, its value is assigned on line 29. That line looks fine (`XMLin` should return a data structure that mimics for XML), so that implies that your data structure is not as you expect. Are you sure that your `$tree->{drug}` branch contains a hash ref and not, for example, an array ref? To interrogate your data structure, try following the directions in Basic debugging checklist and use Data::Dumper or Data::Dump (It looks like you tried that because of your commented `#print pp($alldrug);` line, but then again you can't get that error if `$alldrug` contains what you seem to expect). #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.	[reply] [d/l] [select]
Re: Not a HASH reference by haukex (Archbishop) on Mar 22, 2017 at 16:38 UTC
So do I understand correctly that `@allkeys = keys %$alldrug;` is the line that is throwing the error? What does `print pp($alldrug);` show, and if that shows `undef`, what does `print pp($tree);` show? Also, note that there are much better modules to parse XML than XML::Simple! I would recommend either XML::LibXML or XML::Twig.	[reply] [d/l] [select]
Re: Not a HASH reference by Anonymous Monk on Mar 23, 2017 at 00:07 UTC
Hi, xpath is easy with xpather.pl `use XML::LibXML; my $dom = XML::LibXML->new(qw/ recover 2 /)->load_xml( IO => $in ); for my $key ( $dom->findnodes( q{ /drug/* } ) ){ print $key->nodeName, "\n", $key->nodePath, "\n", $key->textValue, "###\n"; }` [download] If /drug doesn't work then `*[local-name()='drug' ]` will Or even /x:drug if you use sub XML::LibXML::Node::F	[reply] [d/l] [select]
Re: Not a HASH reference by Anonymous Monk on Mar 22, 2017 at 16:09 UTC
`my $tree = $parser->XMLin($in);` [download] `$in` is not being opened. Check the return value. Check for errors.	[reply] [d/l]
Re^2: Not a HASH reference by haukex (Archbishop) on Mar 22, 2017 at 16:53 UTC
`$in` is not being opened. That seems to be very unlikely. Based on `dir(...)`, `->children` and `->openr`, I am guessing this is Path::Class. Its `openr` throws an error if the file couldn't be opened. Even if `$in` were `undef`, there would need to be a file named `tocsvfd.xml` in the same path as the script, otherwise `XMLin` would throw an error.	[reply] [d/l] [select]
Re^2: Not a HASH reference by pdahal (Acolyte) on Mar 22, 2017 at 16:19 UTC
how do I open $in?	[reply]


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