XML::Xpath: How to get string from literal

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

I am trying to use XML::Xpath to parse output from Alexa. The response content looks like this

<?xml version="1.0"?>
<aws:UrlInfoResponse xmlns:aws="http://alexa.amazonaws.com/doc/2005-10
+-05/"><aws:Response xmlns:aws="http://awis.amazonaws.com/doc/2005-07-
+11"><aws:OperationRequest><aws:RequestId>ebd2abff-7c52-49ec-a7f3-7714
+dd3934ec</aws:RequestId></aws:OperationRequest><aws:UrlInfoResult><aw
+s:Alexa>
  
  <aws:TrafficData>
    <aws:DataUrl type="canonical">look_again.blogspot.com/</aws:DataUr
+l>
    <aws:Asin>B00006D9SV</aws:Asin>
    <aws:Rank>14</aws:Rank>
  </aws:TrafficData>
</aws:Alexa></aws:UrlInfoResult><aws:ResponseStatus xmlns:aws="http://
+alexa.amazonaws.com/doc/2005-10-05/"><aws:StatusCode>Success</aws:Sta
+tusCode></aws:ResponseStatus></aws:Response><aws:Response xmlns:aws="
+http://awis.amazonaws.com/doc/2005-07-11"><aws:OperationRequest><aws:
+RequestId>ebd2abff-7c52-49ec-a7f3-7714dd3934ec</aws:RequestId></aws:O
+perationRequest><aws:UrlInfoResult><aws:Alexa>
  
  <aws:TrafficData>
    <aws:DataUrl type="canonical">77708.blogspot.com/</aws:DataUrl>
    <aws:Asin>B00006D9SV</aws:Asin>
    <aws:Rank>14</aws:Rank>
  </aws:TrafficData>
</aws:Alexa></aws:UrlInfoResult><aws:ResponseStatus xmlns:aws="http://
+alexa.amazonaws.com/doc/2005-10-05/"><aws:StatusCode>Success</aws:Sta
+tusCode></aws:ResponseStatus></aws:Response><aws:Response xmlns:aws="
+http://awis.amazonaws.com/doc/2005-07-11"><aws:OperationRequest><aws:
+RequestId>ebd2abff-7c52-49ec-a7f3-7714dd3934ec</aws:RequestId></aws:O
+perationRequest><aws:UrlInfoResult><aws:Alexa>
  
  <aws:TrafficData>
    <aws:DataUrl type="canonical">ddig.blogspot.com/</aws:DataUrl>
    <aws:Asin>B000JFQRGM</aws:Asin>
    <aws:Rank>834337</aws:Rank>
  </aws:TrafficData>
</aws:Alexa></aws:UrlInfoResult><aws:ResponseStatus xmlns:aws="http://
+alexa.amazonaws.com/doc/2005-10-05/"><aws:StatusCode>Success</aws:Sta
+tusCode></aws:ResponseStatus></aws:Response><aws:Response xmlns:aws="
+http://awis.amazonaws.com/doc/2005-07-11"><aws:OperationRequest><aws:
+RequestId>ebd2abff-7c52-49ec-a7f3-7714dd3934ec</aws:RequestId></aws:O
+perationRequest><aws:UrlInfoResult><aws:Alexa>
  
  <aws:TrafficData>
    <aws:DataUrl type="canonical">blog66137.blogspot.com/</aws:DataUrl
+>
    <aws:Asin>B00006D9SV</aws:Asin>
    <aws:Rank>14</aws:Rank>
  </aws:TrafficData>
</aws:Alexa></aws:UrlInfoResult><aws:ResponseStatus xmlns:aws="http://
+alexa.amazonaws.com/doc/2005-10-05/"><aws:StatusCode>Success</aws:Sta
+tusCode></aws:ResponseStatus></aws:Response><aws:Response xmlns:aws="
+http://awis.amazonaws.com/doc/2005-07-11"><aws:OperationRequest><aws:
+RequestId>ebd2abff-7c52-49ec-a7f3-7714dd3934ec</aws:RequestId></aws:O
+perationRequest><aws:UrlInfoResult><aws:Alexa>
  
  <aws:TrafficData>
    <aws:DataUrl type="canonical">webhostingservice-ka.blogspot.com/</
+aws:DataUrl>
    <aws:Asin>B00006D9SV</aws:Asin>
    <aws:Rank>14</aws:Rank>
  </aws:TrafficData>
</aws:Alexa></aws:UrlInfoResult><aws:ResponseStatus xmlns:aws="http://
+alexa.amazonaws.com/doc/2005-10-05/"><aws:StatusCode>Success</aws:Sta
+tusCode></aws:ResponseStatus></aws:Response></aws:UrlInfoResponse>
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The relevant code I am using to look a the file (via the debugger) is

my $output = $response->content;
my $xp = XML::XPath->new(xml => $output);
my $nodeset = $xp->find('/aws:UrlInfoResponse/aws:Response');
my $nnodes = @{ $nodeset };
for my $i (0..$nnodes-1) {
     my $status = $nodeset[$i]->findvalue('/aws:ResponseStatus/aws:Sta
+tusCode');
}
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In this code $status comes back with five XML:Xpath::Node::Element objects like it should, but $status comes back as XML::Xpath::Literal which according to the docs is supposed to be a string, but I can't find a way to get a string out of it. XML::Xpath::Literal is supposed to have a method toString but when I try to apply that as in

my $string = $status->toString
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I get error Can't locate object method "toString" via package "XML::XPath::Literal"

What am i doing wrong?

TIA...

Steve

readmore tags added by Arunbear

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Re: XML::Xpath: How to get string from literal
by ikegami (Patriarch) on Jan 19, 2007 at 22:01 UTC

According to XML::XPath::Literal, objects of that type are overloaded to return a string when needed.

print $status;  # Automatically gets converted to a string.
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The issue can be forced using interpolation, concatenation or the provided method.

my $status_str1 = "$status";      # Auto converted to a string.
my $status_str2 = '' . $status;   # Auto converted to a string.
my $status_str3 = $status->value();
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Re^2: XML::Xpath: How to get string from literal

by cormanaz (Deacon) on Jan 19, 2007 at 22:19 UTC

print $nodeset->[1]->string_value;
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I get

ebd2abff-7c52-49ec-a7f3-7714dd3934ec
  
  
    look_again.blogspot.com/
    B00006D9SV
    14
  
Success
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So I'm a little baffled here...

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Re: XML::Xpath: How to get string from literal
by jettero (Monsignor) on Jan 19, 2007 at 22:00 UTC

I'm pretty sure the method you want is $string = $status->value(). That method is shown on this page XML::XPath::Literal. You were so close!!

The auto string conversion from ikegami's post (below) is news to me. I'm going to use that from now on, where I don't need to be explicit.

-Paul

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Re: XML::Xpath: How to get string from literal
by Jenda (Abbot) on Feb 21, 2007 at 14:19 UTC

Sorry, no XML::Xpath here. Here's what you might do using XML::Rules:

use XML::Rules;

my $parser = XML::Rules->new(
 namespaces => {
    'http://alexa.amazonaws.com/doc/2005-10-05/' => '',
    'http://awis.amazonaws.com/doc/2005-07-11' => '',
 },
 rules => [
    'DataUrl,Asin,Rank,RequestId,StatusCode' => 'content',
    'TrafficData,Alexa,UrlInfoResult,OperationRequest,ResponseStatus' 
+=> 'no content',
    'Response' => sub {
        print <<"*END*"
Do something with request $_[1]->{OperationRequest}{RequestId}, it was
+ a $_[1]->{ResponseStatus}{StatusCode}
 URL: $_[1]->{UrlInfoResult}{Alexa}{TrafficData}{DataUrl}
 Rank: $_[1]->{UrlInfoResult}{Alexa}{TrafficData}{Rank}
*END*
        return;
    }
 ],
);

# or, if you want to simplify the data as you parse them:

my $parser = XML::Rules->new(
 namespaces => {
    'http://alexa.amazonaws.com/doc/2005-10-05/' => '',
    'http://awis.amazonaws.com/doc/2005-07-11' => '',
 },
 rules => [
    'DataUrl,Asin,Rank,RequestId,StatusCode' => 'content',
    'UrlInfoResult,OperationRequest' => 'no content',
    'TrafficData,Alexa' => 'pass no content',
    'ResponseStatus' => sub { return 'ResponseStatus' => $_[1]->{Statu
+sCode}},
    'Response' => sub {
        print <<"*END*"
Do something with request $_[1]->{OperationRequest}{RequestId}, it was
+ a $_[1]->{ResponseStatus}
 URL: $_[1]->{UrlInfoResult}{DataUrl}
 Rank: $_[1]->{UrlInfoResult}{Rank}
*END*
        return;
    }
 ],
);
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Jenda
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