Consider an Xml document that contains an element <A>. This element contains several elements all named <B>. Each of these elements contains a number of elements.
I want to get a node set, containing the first element in every <B> element, in order of appearance.
You may want to consider this XPath :
//B/*[1]
The first bit of the XPath (//B) looks for all <B> elements. Then from each <B> element, the next bit (/*[1]) will return the first child element.
Sample XML (OP should've been the one who posted an example though, to make his question clearer) :
<A>
<B>
<foo/>
<bar/>
</B>
<B>
<foo/>
<bar/>
</B>
<B>
<foo/>
<bar/>
</B>
</A>
And the output of above XPath in an online xpath tester by freeformatter :
Element='<foo />'
Element='<foo />'
Element='<foo />'
Is this what you are after?
<?xml version="1.0"?>
<root>
<a>
<b><c id="1" /></b>
<b><c id="2" /></b>
</a>
<a>
<b><c id="3" /></b>
<b><c id="4" /></b>
<b><c id="5"/></b>
<b>
<c id="6" />
<c id="7" />
</b>
</a>
<a>
<f><c id="3" /></f>
<b><d id="4" /></b>
</a>
With XPath of
root/a/b[position() = 1]
Resulting in:
<?xml version="1.0" encoding="UTF-8"?>
<root>
<b>
<c id="1"/>
</b>
<b>
<c id="3"/>
</b>
<b>
<d id="4"/>
</b>
</root>
Given an example input XML
<root>
<A>
<B>B 1 1</B>
<B>B 1 2</B>
</A>
<A>
<B>B 2 1</B>
<B>B 2 2</B>
</A>
</root>
the following XPath
//A//B[1]/text()
has the result
B 1 1
B 2 1
as every first B that is a child element of A is selected.
Using //A//B[1] will result in the complete B nodes:
<B>B 1 1</B>
<B>B 2 1</B>
Related
I have an xml file in linux that I want to process.
I need to get all ids of a parent nodes based on its children.
Here I want to get all id of 'a' that have 'c' without key "f.g".
<a id="11111">
<b>
<c key="d.e">stuff1</c>
<c key="f.g">stuff2</c>
<c key="j.k">stuff4</c>
</b>
</a>
<a id="22222">
<b>
<c key="d.e">stuff1</c>
<c key="h.i">stuff3</c>
<c key="j.k">stuff4</c>
<c key="l.m">stuff5</c>
</b>
</a>
<a id="33333">
<b>
<c key="c.d">stuff0</c>
<c key="d.e">stuff1</c>
<c key="h.i">stuff3</c>
<c key="j.k">stuff4</c>
<c key="l.m">stuff5</c>
</b>
</a>
In this case I should be getting 22222 and 33333.
I'm not really sure how to write the xpath for this.
I think you are looking for something like:
//a[not(.//c[#key="f.g"])]/#id
which can be translated as: find any node <a> which does NOT have a child node <c> which itself has an attribute called key which itself has an attribute value of "f.g".
You can filter by (not):
//a[[not(#key = 'f.g')]]
It will return you needed 'a' elements, but I don't know how to get their ids.
#Jack Fleeting's answer is probably the best solution. As an alternative (more consuming) :
//c[not(#key="f.g" or preceding-sibling::c[#key="f.g"] or following-sibling::c[#key="f.g"])]/ancestor::a
Look for c elements where itself, and preceding or following siblings contain an attribute different from #key="f.g". Then select their a ancestors.
I need select a specific node name closest to (not needly on) root.
Example:
<root>
<a>
<b id="1"></b>
<b id="2">
<b id="3"></b>
</b>
<c>
<b id="4"></b>
</c>
</a>
</root>
It should select b#1, b#2 and b#4, but not b#2, because it is included inside of another b node.
Currently I'm doing that: select all b, so check if some of parents is b, if yes, discard that. But I do it hardcoded, maybe xpath can solve that alone?
I found the solution, just using not + ancestor, like:
//table[not(ancestor::table)]
I would try below expression-
//b[not(.//ancestor::b)]
It selects-
<b id="1"/>
<b id="4"/>
See live at here.
I have html structure like this:
<a>
<c>
</c>
</a>
<b>
<d>
</d>
</b>
<a>
<c>
</c>
</a>
<b>
<d>
</d>
</b>
How do I group node 'a' and node 'b' together?
The xpath should be able to select the pairs of node 'a' and 'b'.
The nodes have auto generated id's and name's so I can't use them in xpath.
You can use the | operator for two unrelated XPath Expressions:
(//a | //b)
Given xml
<a>
<b key=1>
<c value=xxx />
</b>
<b key=2>
<c value=yyy />
</b>
</a>
Goal: Get each "b" first, then get the "c" under that "b", like result below. With XPath for searching child.
for <b key=1>
<c value=xxx />
for <b key=2>
<c value=xxx />
but below code
b_elements = XPath.match(xml, "//b[#key]")
b_elements.each do |b_element|
puts b_element.elements["//c"]
end
will result in yeilding
for <b key=1>
<c value=xxx />
<c value=yyy />
for <b key=2>
<c value=xxx />
<c value=yyy />
instead of just getting the "c" under each "b"
I had tried below method but no luck, seems that if using Xpath, it will automatically search from root element
b.get_elements("//c")
XPath.first(b, "//c")
My workaround now is traverse child element 1 layer at a time and search for desired key, which seems quite stupid comparing to using XPath.
Please advise, thanks : )
Reference:
http://ruby-doc.org/stdlib-1.9.3/libdoc/rexml/rdoc/REXML/Element.html#method-i-each_element_with_attribute
Not sure here, but my assumption is that XPath looks at the first char, sees that it is a /, and thinks that the path is absolute (because the path starting with / is meant to be absolute).
Probably you can force the path to be relative by using a . before //, so the parser doesn't confuse // for /?
I mean, instead of "//c" use ".//c"? Hope this helps.
I have a transform that looks like this
<configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform">
<a>
<b>
<c>
<d>
<e name="UpdateLanguageProfile">
<f xdt:Transform="Replace" xdt:Locator="Condition(/..#name='UpdateLanguageProfile')">
stuff here
</f>
</e>
</d>
</c>
</b>
</a>
So I want the xdt:Locator to select the f node only if the parent node has an attribute with the specified value.
The xdt:Locator gets translated into the following xpath expression:
/a/b/c/d/e/f[/..#name='UpdateLanguageProfile']
Which is invalid.
So the question is, what could I put in the Condition, that is the XPath square brackets, in order to select the f node based on an attribute in the parent node.
The answer is that the xdt:Locator and the xdt:Transform do not need to be on the same node. They just happen to be on the same node in every example I've ever seen.
You can do this:
<configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform">
<a>
<b>
<c>
<d>
<e name="UpdateLanguageProfile" xdt:Locator="Match(name)">
<f xdt:Transform="Replace">
stuff here
</f>
</e>
</d>
</c>
</b>
</a>