Member Avatar for Vishwanath_1

Hi,
I am very new to this forum. I started learning XPath queries.
Can anyone please assist me on how to get elements from an xml where it doesn't contains any root element.

Thanks,
Vishwanath

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  • Latest Post Latest Post by xml_looser

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Short answer: XPath runs against a parsed XML document (an infoset), so you must feed a well-formed XML document to your parser. As pointed out, XML requires exactly one document element; the DOMDocument error you saw happens because the fragment contains multiple top-level elements. Two practical options follow.

Wrap the fragment in a temporary root before parsing (example in PHP):

<?php
$fragment = '<item id="i2"><title>Example</title></item><item id="i3"><title>Other</title></item>';
$fragment = preg_replace('/^<\?xml.*?\?>\s*/', '', $fragment); // strip any XML declaration
$xml = '<root>' . $fragment . '</root>';

$doc = new DOMDocument();
$doc->loadXML($xml);
$xpath = new DOMXPath($doc);
$node = $xpath->query('/root/item[@id="i2"]/title')->item(0);
echo $doc->saveXML($node);

Or do the same with Python + lxml:

import re
from lxml import etree

fragment = '<item id="i2"><title>Example</title></item><item id="i3"><title>Other</title></item>'
fragment = re.sub(r'^<\?xml.*?\?>\s*', '', fragment)
doc = etree.fromstring('<root>' + fragment + '</root>')
print(doc.xpath('/root/item[@id="i2"]/title/text()')[0])

Notes and gotchas: remove any internal XML declaration before wrapping (two declarations will break parsing); if your elements use a default namespace you must register a prefix for XPath lookups; for very large streams prefer a streaming parser (iterparse, XmlReader, SAX) and handle elements one by one instead of loading the whole string; never try to reliably parse XML with plain regex. This approach lets you run XPath against fragments even when the original input lacks a single root, and it addresses the exact DOMDocument error that encountered.

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Member Avatar for Vishwanath_1

For example, I wan tto find the book element where the book id is bk101 from the below xml conetent:

<book id="bk101">
      <author>Gambardella, Matthew</author>
      <description>with XML.</description>
</book>
<book id="bk201">
      <author>Gambardella, Matthew</author>
      <description>with XML.</description>
</book>
<book id="bk301">
      <author>Gambardella, Matthew</author>
      <description>with XML.</description>
</book>

Thanks in advance,
Vishwanath

Member Avatar for xml_looser

Each xml file must have a root node, this is a
xml condition

xpath but can also be wendt without root knot

tutorial
Click Here
example5

example6
Click Here

without rootnode

//book[@id="bk201"]/author

result

<author>Gambardella, Matthew</author>

I hope this helps

Member Avatar for Vishwanath_1

Thanks for the quick reply.

I tried the same in http://www.online-toolz.com/tools/xpath-editor.php
But I got an error:
*
Error:DOMDocument::loadXML() [<a href='domdocument.loadxml'>domdocument.loadxml</a>]: Extra content at the end of the document in Entity, line: 5*

Any help is appreciated

Thanks,
Vishwanath

Member Avatar for xml_looser

copy in xml window

<?xml version="1.0"?>
<bookstore>
    <book id="bk101">
        <author>Gambardella, Matthew</author>
        <description>with XML.</description>
    </book>
    <book id="bk201">
        <author>Gambardella, Matthew</author>
        <description>with XML.</description>
    </book>
    <book id="bk301">
        <author>Gambardella, Matthew</author>
        <description>with XML.</description>
    </book>
</bookstore>

and in xpath window

//book[@id="bk201"]/author

result

<author>Gambardella, Matthew</author>

if you not root node indicates it will never go
there are semi-regular in xml to which one must adhere to in order to apply it to

without rootnode

error

Error:DOMDocument::loadXML() [<a href='domdocument.loadxml'>domdocument.loadxml</a>]: Extra content at the end of the document in Entity, line: 5
Member Avatar for Vishwanath_1

Hi,
If the xml has root node, I am able to get the result. But I want to try XPath to get a particular book where the xml will not have a root node. There are multiple book elements exists with different ids but these elements are not wrapped under a root node.

As I mentioned in my first post, there is no root element.

Thanks,
Vishwanath

Member Avatar for xml_looser

xpath evaluations go only with valid xml files

for me the question is answered herewith
to regulate the keeping of xml
in xpath then ask without rootnode with '/ /'
the means to address all child nodes

Member Avatar for Vishwanath_1

So, We can't do XPath query agaonst the xml data which doesn't have a root node?

Member Avatar for xml_looser

everything which does not comply with the rules of xml
is not xml
see html xml is similar but is not xml
only by restrictions and user-dtd
and so from version 5 it is always more to xml

I suspect your question is create xpath request
without the root node to use and comes with 2 flash
the node and determine with the help xpath and attribute
is the node found

xml file

<?xml version="1.0"?>
    <bookstore>
    <book id="bk101">
    <author>Gambardella, Matthew</author>
    <description>with XML.</description>
    </book>
    <book id="bk201">
    <author>Gambardella, Matthew</author>
    <description>with XML.</description>
    </book>
    <book id="bk301">
    <author>Gambardella, Matthew</author>
    <description>with XML.</description>
    </book>
    </bookstore>

xpath

//*[@id="bk101"]

result

<author>Gambardella, Matthew</author>
<description>with XML.</description>
</book>
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