XSLT 1.0:从外部文档中提取顺序信息 [英] XSLT 1.0: extract sequential infromation from external document
问题描述
我正在尝试使用 xslt 执行 xml 到 xml 的转换,这样每个元素都有一个 GUID,按顺序从外部 xml 文档中提取.
源 xml:
<数据集><data name="foo"/><data name="bar"/>...</数据集>
ID 列表:
<ids><id>some-GUID</id><id>another-GUID</id>...</ids>
所需的输出:
<数据集><data name="foo" id="some-GUID"/><data name="bar" id="another-GUID"/>...</数据集>
但我每次都得到相同的第一个 ID:
<数据集><data name="foo" id="some-GUID"/><data name="bar" id="some-GUID"/>...</数据集>
到目前为止,这是我得到的 xsl:
<xsl:transform version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"><xsl:template match="/|node()|@*"><xsl:copy><xsl:apply-templates select="node()|@*"/></xsl:copy></xsl:模板><xsl:template match="dataSets"><xsl:for-each select="data"><xsl:variable name="c"><xsl:number value="count(preceding-sibling::*|self::*)"/></xsl:变量><xsl:copy><xsl:attribute name="id"><xsl:value-of select="document('idList.xml')/ids/id[$c]"/></xsl:attribute><xsl:apply-templates select="node()|@*"/></xsl:copy></xsl:for-each></xsl:模板></xsl:transform>
我尝试添加 <xsl:attribute name="num"><xsl:value-of select="$c"/></xsl:attribute>
到 xsl 以查看每次迭代时变量是什么,它从 1 开始,每次通过 for-each
递增,正如我所期望的那样,所以我不知道为什么它不起作用.
任何帮助将不胜感激.
怎么样:
XSLT 1.0
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/><xsl:strip-space elements="*"/><!-- 身份变换--><xsl:template match="@*|node()"><xsl:copy><xsl:apply-templates select="@*|node()"/></xsl:copy></xsl:模板><xsl:template match="数据"><xsl:copy><xsl:copy-of select="@*"/><xsl:variable name="i" select="count(preceding::data) + 1"/><xsl:attribute name="id"><xsl:value-of select="document('idList.xml')/ids/id[$i]"/></xsl:attribute></xsl:copy></xsl:模板></xsl:stylesheet>
注意:
如果所有
data
元素都是同一个dataSets
父元素下的兄弟元素,你可以通过只计算前面的兄弟元素来加快速度:可能有更好的方法将 GUID 分配给节点.
<小时>
补充说明:
您的尝试不起作用的原因是两个因素的组合:
首先,定义变量的方式:
<xsl:number value="count(preceding-sibling::*|self::*)"/></xsl:变量>
导致变量成为结果树片段.该变量包含单个根节点,xsl:number
生成的字符串是该节点的子节点.
接下来,您尝试将该变量用作表达式中的数字谓词:
然而,由于变量不是一个数字,它被评估为一个布尔值 - 并且非空返回true,导致all id
节点以通过测试(当然,在 XSLT 1.0 中 xsl:value
将只返回其中第一个的值).
如何解决:
您可以通过三种方法解决此问题:
不要将变量用作数字谓词.相反,将它放在一个表达式中,将其与位置显式进行比较(如@potame 的回答中所建议的那样):
在将其用作谓词之前将其转换为数字:
通过使用
select
属性定义变量,从一开始就消除问题,这将导致变量成为以数字开头的数字:<xsl:variable name="c" select="count(preceding-sibling::*|self::*)"/>
另见:
http://www.w3.org/TR/xslt/#variable-values>
http://www.w3.org/TR/xpath/#predicates>
I am trying to use xslt to perform an xml to xml transform, such that each element is given a GUID, pulled in sequential order from an external xml document.
Source xml:
<?xml version="1.0"?>
<dataSets>
<data name="foo"/>
<data name="bar"/>
...
</dataSets>
List of IDs:
<?xml version="1.0"?>
<ids>
<id>some-GUID</id>
<id>another-GUID</id>
...
</ids>
Desired output:
<?xml version="1.0"?>
<dataSets>
<data name="foo" id="some-GUID"/>
<data name="bar" id="another-GUID"/>
...
</dataSets>
But I'm just getting the same, first ID each time:
<?xml version="1.0"?>
<dataSets>
<data name="foo" id="some-GUID"/>
<data name="bar" id="some-GUID"/>
...
</dataSets>
So far this is the xsl I've got:
<?xml version="1.0"?>
<xsl:transform version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/|node()|@*">
<xsl:copy>
<xsl:apply-templates select="node()|@*"/>
</xsl:copy>
</xsl:template>
<xsl:template match="dataSets">
<xsl:for-each select="data">
<xsl:variable name="c">
<xsl:number value="count(preceding-sibling::*|self::*)"/>
</xsl:variable>
<xsl:copy>
<xsl:attribute name="id">
<xsl:value-of select="document('idList.xml')/ids/id[$c]"/>
</xsl:attribute>
<xsl:apply-templates select="node()|@*"/>
</xsl:copy>
</xsl:for-each>
</xsl:template>
</xsl:transform>
I've tried adding <xsl:attribute name="num"><xsl:value-of select="$c"/></xsl:attribute>
to the xsl to see what the variable is each time it iterates and it starts at 1 and increments each time through the for-each
just as I'd expect so I've no idea why it's not working.
Any help would be appreciated.
How about:
XSLT 1.0
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:strip-space elements="*"/>
<!-- identity transform -->
<xsl:template match="@*|node()">
<xsl:copy>
<xsl:apply-templates select="@*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="data">
<xsl:copy>
<xsl:copy-of select="@*"/>
<xsl:variable name="i" select="count(preceding::data) + 1" />
<xsl:attribute name="id">
<xsl:value-of select="document('idList.xml')/ids/id[$i]"/>
</xsl:attribute>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
Note:
If all
data
elements are siblings under the samedataSets
parent, you can expedite this by counting only the preceding siblings:<xsl:variable name="i" select="count(preceding-sibling::data) + 1" />
There are probably better ways to assign GUIDs to nodes.
Addditional explanation:
The reason why your attempt does not work is a combination of two factors:
First, the way you define your variable:
<xsl:variable name="c">
<xsl:number value="count(preceding-sibling::*|self::*)"/>
</xsl:variable>
results in the variable being a result tree fragment. The variable contains a single root node, and the string generated by xsl:number
is a child of that node.
Next, you try to use the variable as a numeric predicate in the expression:
<xsl:value-of select="document('idList.xml')/ids/id[$c]"/>
However, since the variable is not a number, it is evaluated as a boolean - and being non-empty it returns true, causing all id
nodes to pass the test (and, of course, in XSLT 1.0 xsl:value
will only return the value of the first one of these).
How to fix it:
There are three ways you can fix this problem:
Do not use the variable as a numeric predicate. Instead, put it in an expression that compares it to the position explicitly (as suggested in the answer by @potame):
<xsl:value-of select="document('idList.xml')/ids/id[position()=$c]"/>
Convert it to number before using it as a predicate:
<xsl:value-of select="document('idList.xml')/ids/id[number($c)]"/>
Eliminate the problem right from the start by defining the variable using the
select
attribute, which will cause the variable to become a number to begin with:<xsl:variable name="c" select="count(preceding-sibling::*|self::*)" />
See also:
http://www.w3.org/TR/xslt/#variable-values
http://www.w3.org/TR/xpath/#predicates
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