I'm a bit confused about this key function:
<xsl:for-each select="article[count(. | key('idkey', #id)[1]) = 1]>
Is there anyone that can briefly explain whats happening in this for-each loop?
The key is: <xsl:key name="idkey" match="/newspapers/newspaper" use="#id"/>
#id is an attribute in newspaper.
Thanks.
The expression key('idkey', #id)[1] selects the first element whose idkey is equal to #id.
The expression count(A|B) = 1 is an insane XSLT 1.0 workaround for testing whether A and B are the same node. (You will also see people using generate-id(A)=generate-id(B) for this.)
Put these together and you are asking whether the current element is the first one in the document that has a particular id value.
This is the basis of the technique called Muenchian Grouping (which becomes redundant in XSLT 2.0).
There is something fishy about the code because the key seems to be matching newspaper id's, not article id's. But perhaps they are related in some way.
In this for-each element
<xsl:for-each select="article[count(. | key('idkey', #id)[1]) = 1]">
The for-each is being applied to the first article element for each #id attribute.
The call key('idkey', #id) is selecting all article elements with the same #id attribute as the current one.
key('idkey', #id)[1] selects the first of all article elements with the same #id.
Because a node cannot appear in a node set more than once, the union . | key('idkey', #id)[1] will contain one node if the current article is the same node as the first article with the same #id. Otherwise it will contain two.
Checking that the value of count() is one selects only the elements that are the first with any #id.
An alternative way of doing this, and the one I prefer, is to use generate-id like this
select="article[generate-id() = generate-id(key('idkey', #id)[1])]"
which checks directly whether the current element is the same one as the first element in the set by comparing their generated IDs.
Related
I have some trouble with a special XML-document.
The XML has only 3 nodes like the below the example:
<solidName>
<unknownNodeName>
<everytimeTheSame>blablabla</everytimeTheSame>
<everytimeTheSame2>blablabla</everytimeTheSame2>
<unknownChildNodeName>
<everytimeTheSame>blablabla</everytimeTheSame>
<everytimeTheSame2>blablabla</everytimeTheSame2>
</unknownChildNodeName>
</unknownNodeName>
</solidName>
I need to select the unknownNodeName and the unknownChildNodeName to use the function
<xsl:value-of select="everytimeTheSame"/> and so on. I tried to use a for-each select function, but I found no way to get the unknow Name of the node.
Are there any possibilities for my problem? Is it possible to say <xsl:for-each select ="NodeNumberX"> or things like that <xsl:for-each select ="/*/*">
to use the function and so on
is not a good description of what you want to do.
Selecting "unknown nodes" (i.e. nodes whose name you do not know, but you do know their position in the document's tree) is trivial by using the * symbol in an XPath expression, possibly combined with a positional predicate.
For example:
/*/*/*[2]
will select the <everytimeTheSame2> element in your example.
I have the following XML snippet:
<figure customer="ABC DEF">
<image customer="ABC"/>
<image customer="XYZ"/>
</figure>
I'd like to check if the figure element's customer attribute contains the customer attributes of the image elements.
<xsl:if test="contains(#customer, image/#customer)">
...
</xsl:if>
I get an error saying:
a sequence of more than one item is not allowed as the second argument of contains
It's important to note that I cannot tell the values of the customer attributes in advance, thus using xsl:choose is not an option here.
Is it possible to solve this without using xsl:for-each?
In XSLT 2.0 you can use:
test="image/#customer/contains(../../#customer, .) = true()"
and you will get a true() result if any of them are true. Actually, that leads me to suggest:
test="some $cust in image/#customer satisfies contains(#customer, $cust)"
but that won't address the situation where the customer string is a subset of another customer string.
Therefore, perhaps this is best:
test="tokenize(#customer,'\s+') = image/#customer"
... as that will do a string-by-string comparison and give you true() if any of the tokenized values of the figure attribute is equal to one of the image attributes.
I want to see if the parent node of the current node I am referring to is equal to a particular value. I did it as follows but no use.
eg.
<v:name>
<v:age>
when at "age" I tried <xsl:if test='.. = v:name'>. But it is not correct. What is the correct way? Can someone help?
I am inside a template which is true for both v:name and v:age. There are v:age's which are not children of v:name. I want to ensure that v:age I am referring to is a child of a v:name. That is what I want inside the test attribute.
From a comment by the OP:
I am inside a template which is true for both v:name and v:age.
There are v:age's which are not children of v:name. I want to
ensure that v:age I am referring to is a child of a v:name. That
is what I want inside the test attribute
Use:
parent::v:name
And this in a xsl:if becomes:
<xsl:if test="parent::v:name">
<!-- Whatever processing is necessary. -->
</xsl:if>
Use <xsl:if test="../v:name = 'somevalue'></xsl:if> or <xsl:if test="parent::v:name = 'somevalue'></xsl:if>
I suspect that when you say you want to know if the parent node is "equal" to a particular value, you really mean that you want to know whether its name is equal to a particular value (this would be immediately clear if you gave examples of your input and output).
If my conjecture is correct, use <xsl:if test="parent::xyz">
<xsl:apply-templates mode="block2sequence" select="NewDataSet/Table[CTD_CTD_PKG_ID =$PackageId][position()=1] and NewDataSet/Table[CTD_SEQ_NUM =$strXSLMsgType][position()=1]"/>
why cant i use two conditions in above select condition, can any one suggest me
<xsl:apply-templates mode="block2"
select="NewDataSet/Table[CTD_CTD_PKG_ID =$PackageId][position()=1] "/>
why cant i use two conditions in above select condition
I guess this is to mean, "why can't the two conditions be specified in the same predicate?"
The answer is that the expression:
NewDataSet/Table[CTD_CTD_PKG_ID =$PackageId and position() = 1]
isn't equivalent at all to the 1st expression above.
The first expression selects the first Table child of NewDataSet such that the string value of its CTD_CTD_PKG_ID child is equal to the string value of $PackageId. In this case we don't know which child (at which position) of NewDataSet will be selected -- any child that happens to be the first with the specified properties, will be selected.
On the other side, the latter expression selects the first Table child of NewDataSet only if the string value of its CTD_CTD_PKG_ID child is equal to the string value of $PackageId. In this case, if anything is selected, it would be the first Table child.
If you want an equivalent expression to the first one, that has only one predicate, one such expression is:
NewDataSet/Table
[CTD_CTD_PKG_ID =$PackageId
and
not(preceding-sibling::Table[CTD_CTD_PKG_ID =$PackageId ])
]
Update: The OP has published a code snippet:
<xsl:apply-templates mode="block2sequence" select=
"NewDataSet/Table[CTD_CTD_PKG_ID =$PackageId][position()=1]
and
NewDataSet/Table[CTD_SEQ_NUM =$strXSLMsgType][position()=1]"/>
This code will cause an error thrown at compile time by the XSLT processor.
The value of the select attribute is a boolean (expr1 and expr2), however templates in XSLT 1.0 and XSLT 2.0 can only be applied on nodes. A boolean isn't a node -- hence the error.
Solution:
My first guess is that you want templates to be applied on both nodes. If this is so, then use:
<xsl:apply-templates mode="block2sequence" select=
"NewDataSet/Table[CTD_CTD_PKG_ID =$PackageId][1]
|
NewDataSet/Table[CTD_SEQ_NUM =$strXSLMsgType][1]"/>
My second guess is that you want templates applied only on the first of the two nodes. If this is so, then use:
<xsl:apply-templates mode="block2sequence" select=
"(NewDataSet/Table[CTD_CTD_PKG_ID =$PackageId]
|
NewDataSet/Table[CTD_SEQ_NUM =$strXSLMsgType]
)
[1]
"/>
Notes:
Please, learn how to ask a question -- provide all relevant data and explain -- in the question, not in subsequent comments.
Did you know that [1] is equivalent to [position()=1] and is shorter?
You can use two conditions and your expression looks perfectly correct. If it is failing with an error, please tell us the error. If it is not selecting what you want, then (a) show us your source document, and (b) tell us what you want to be selected.
(You know, your question gives so little information, you don't give the impression that you really want an answer.)
Given
<xsl:variable name="datePrecision" as="element()*">
<p>Year</p>
<p>Month</p>
<p>Day</p>
<p>Time</p>
<p>Timestamp</p>
</xsl:variable>
The expression
$datePrecision[5]
returns a nodeSet containing one text node with value "Timestamp", as expected.
Later in a template, with a context element having an attribute
#precision="5"
I try the following expressions but all return an empty string:
$datePrecision[#precision]
$datePrecision[number(#precision)]
$datePrecision[xs:decimal(#precision)]
However, the following sequence does what I want
<xsl:variable name="prec" select="number(#precision)"/>
... $datePrecision[$prec] ...
Using Oxygen/XML's debugger I've stepped to the point where the expression is about to be evaluated and display the following in the watch window:
Expression Value Nodes/Values Set
-------------------------- --------------- -----------------------
$datePrecision[5] Node Set(1) #text Timestamp
#precision Node Set(1) precision 5
$datePrecision[#precision]
number(#precision) 5
$datePrecision[number(#precision)]
$prec 5
$datePrecision[$prec] Node Set(1) #text Timestamp
Obviously I've missed something fundamental about how attribute nodes are atomized for use in a predicate, but can't find anything in the docs (Michael Kay's XSLT/XPATH 2.0, 4th ed) that would explain this difference.
Can someone explain why this is occurring, and point me to where, in either the XSLT 2.0 spec or Michael Kay's book, where this is described?
(the XSLT processor is Saxon-PE 9.2.0.3)
Obviously I've missed something
fundamental
Yes. The XPath expression:
$datePrecision[#precision]
means: all elements in $datePrecision that have an attribute named precision.
But you want #precision to mean the attribute named precision of the currnet node that is matched by the template.
XSLT provides the current() function exactly for this purpose. Use:
$datePrecision[current()/#precision]
UPDATE: As Martin Honnen hinted, the OP probably wants to get the 5th element out of $datePrecision -- something not immediately visible from the description of the problem. In this case, it may be necessary to use:
$datePrecision[position() = current()/#precision]