I am using a mapping node in my messageflow and there is a part where i need to
conatenate a string/character n times in xpath function.
Is there any way to do this with some
xpath expression or xpath build function (or both) ?
for example: concatenate '~' 17 times.
Easy in XPath 2.0:
string-join(for $i in 1 to 17 return '~', '')
Easier still in XPath 3.0:
string-join((1 to 17)!'~')
In XPath 1.0 your best bet is probably to initialize a variable $tildes with 100 (or however many) tildes, and then use
substring($tildes, 1, 17)
Related
I have a short question. How can I display only the elements who's value is = '.'
I have no idea how to do that. I'm newbie in XPath.
<SalesTransaction>
<TransactionHeader>
<TransactionHeaderFields>
<WrntyID>a</WrntyID>
<ExternalID/>
<Type>.</Type>
<Status>
Submited
</Status>
<CreationDate>
2015-01-12
</CreationDate>
<Date>
2015-01-12T11:41:29Z
</Date>
<DeliveryDate>
2015-01-12
</DeliveryDate>
<Remark/>
</TransactionHeaderFields>
<CatalogFields>
<CatalogID>
saf
</CatalogID>
</CatalogFields>
</TransactionHeader>
</SalesTransaction>
Ignoring any of the structure and just looking for any element who's text() is equal to ".", you could use:
//*[text()='.']
//* will search through the entire tree structure, looking for any element at any level
[text()='.'] is a predicate filter (kind of like a WHERE clause in SQL) that performs a test on each of those matched elements. Only the ones that have a text() node who's value is equal to . will evaluate to true() and will be what is left.
It's not not he most efficient XPath expression, but may be good enough for what you need.
Given the following markup:
<div id="about">
<dl>
<dt>Date</dt>
<dd>1872</dd>
<dt>Names</dt>
<dd>A</dd>
<dd>B</dd>
<dd>C</dd>
<dt>Status</dt>
<dd>on</dd>
<dt>Another Field</dt>
<dd>X</dd>
<dd>Y</dd>
</dl>
</div>
I'm trying to extract all the <dd> nodes following <dt>Names</dt> but only until another <dt> starts. In this case, I'm after the following nodes:
<dd>A</dd>
<dd>B</dd>
<dd>C</dd>
I'm trying the following XPath code, but it's not working as intended.
xpath("//div[#id='about']/dl/dt[contains(text(),'Names')]/following-sibling::dd[not(following-sibling::dt)]/text()")
Any thoughts on how to fix it?
Many thanks.
Update: much simpler solution
There is a prerequisite in your situation, that is that the anchor item always is the first preceding sibling with a certain property. Because of that, here's a much simpler way of writing the below complex expression:
/div/dl/dd[preceding-sibling::dt[1][. = 'Names']]
In other words:
select any dd
that has a first preceding sibling dt (the preceding sibling axis counts backwards)
that itself has a value of "Names"
As can be seen in the following screenshot from oXygen, it selects the nodes you wanted to select (and if you change "Names" to "Status" or "Another Field", it will select only the following ones before the next dt also).
Original complex solution (leaving in for reference)
This is far easier in XPath 2.0, but let's assume you can only use XPath 1.0. The trick is to count the number of preceding siblings from your anchor element (the one with "Names" in it), and disregard any that have the wrong count (i.e., when we cross over <dt>Status</dt>, the number of preceding siblings has increased).
For XPath 1.0, remove the comments between (: and :) (in XPath, whitespace is insignificant, you can make it a multiline XPath for readability, but in 1.0, comments are not possible)
/div/dl/dd
(: any dd having a dt before it with "Names" :)
[preceding-sibling::dt[. = 'Names']]
(: count the preceding siblings up to dt with "Names", add one to include 'self' :)
[count(preceding-sibling::dt[. = 'Names']/preceding-sibling::dt) + 1
=
(: compare with count of all preceding siblings :)
count(preceding-sibling::dt)]
As a one-liner:
/div/dl/dd[preceding-sibling::dt[. = 'Names']][count(preceding-sibling::dt[. = 'Names']/preceding-sibling::dt) + 1 = count(preceding-sibling::dt)]
How about this:
//dd[preceding-sibling::dt[contains(., 'Names')]][following-sibling::dt]
Is it possible to select nodes in a similar way?
'./tr[position() in (1, 3, 7)]'
I found only this solution:
'./tr[position() = 1 or position() = 3 or position() = 7]'
In XPath 2.0 you would simply do:
./tr[position = (1,3,7)]
In XPath 1.0 the usual way to do it is the solution you already found, an alternative that is a bit shorter would be something like:
./tr[contains('1 3 7', position())]
The spaces in the string are essential here, otherwise you'd also get nodes 13,37 and 137.
I'm new to xpath and I understand how to get a range of values in xpath:
/bookstore/book[position()>=2 and position()<=10]
but in my case, I need to get above 2 and one less then the total(so if there's 10 then I need 9, or if there's 5, I need up to the 4th spot). I'm applying my code to different pages and the number of entries is not always the same.
In python, I could do something like book[2:-2], but I'm unsure if I can do this within xpath.
You can use last() which represents the last item in the context:
/bookstore/book[position()>=2 and position() <= (last() - 1)]
In my case this was working for me to get last but one element
/bookstore/book[position() = (last() - 1)]
Using the count(preceding-sibling::*) XPath expression one can obtaining incrementing counters. However, can the same also be accomplished in a two-levels deep sequence?
example XML instance
<grandfather>
<father>
<child>a</child>
</father>
<father>
<child>b</child>
<child>c</child>
</father>
</grandfather>
code (with Saxon HE 9.4 jar on the CLASSPATH for XPath 2.0 features)
Trying to get an counter sequence of 1,2 and 3 for the three child nodes with different kinds of XPath expressions:
XPathExpression expr = xpath.compile("/grandfather/father/child");
NodeList nodes = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
for (int i = 0 ; i < nodes.getLength() ; i++) {
Node node = nodes.item(i);
System.out.printf("child's index is: %s %s %s, name is: %s\n"
,xpath.compile("count(preceding-sibling::*)").evaluate(node)
,xpath.compile("count(preceding-sibling::child)").evaluate(node)
,xpath.compile("//child/position()").evaluate(doc)
,xpath.compile(".").evaluate(node));
}
The above code prints:
child's index is: 0 0 1, name is: a
child's index is: 0 0 1, name is: b
child's index is: 1 1 1, name is: c
None of the three XPaths I tried managed to produce the correct sequence: 1,2,3. Clearly it can trivially be done using the i loop variable but I want to accomplish it with XPath if possible. Also I need to keep the basic framework of evaluating an XPath expression to get all the nodes to visit and then iterating on that set since that's the way the real application I work on is structured. Basically I visit each node and then need to evaluate a number of XPath expressions on it (node) or on the document (doc); one of these XPAth expressions is supposed to produce this incrementing sequence.
Use the preceding axis with a name test instead.
count(preceding::child)
Using XPath 2.0, there is a much better way to do this. Fetch all <child/> nodes and use the position() function to get the index:
//child/concat("child's index is: ", position(), ", name is: ", text())
You don't say efficiency is important, but I really hate to see this done with O(n^2) code! Jens' solution shows how to do that if you can use the result in the form of a sequence of (position, name) pairs. You could also return an alternating sequence of strings and numbers using //child/(string(.), position()): though you would then want to use the s9api API rather than JAXP, because JAXP can only really handle the data types that arise in XPath 1.0.
If you need to compute the index of each node as part of other processing, it might still be worth computing the index for every node in a single initial pass, and then looking it up in a table. But if you're doing that, the simplest way is surely to iterate over the result of //child and build a map from nodes to the sequence number in the iteration.