如何使用XSLT 2.0按条件修改指定XML字段的值

需求很明确：遍历XML中所有/message/object/struct/substruct2/ss2field2字段，只要字段值以字符"i"结尾，就在值前面加一个"0"。

源XML如下：

<message>
    <object>
        <meta>
            <field>text</field>
        </meta>
        <struct>
            <sfield1>text</sfield1>
            <sfield2>text</sfield2>
            <substruct1>
                <ss1field>text</ss1field>
            </substruct1>
            <substruct2>
                <ss2field1>text</ss2field1>
                <ss2field2>0001</ss2field2>
            </substruct2>
            <substruct2>
                <ss2field1>text</ss2field1>
                <ss2field2>002i</ss2field2>
            </substruct2>
            <substruct2>
                <ss2field1>text</ss2field1>
                <ss2field2>0003</ss2field2>
            </substruct2>
        </struct>
    </object>
    <object>
        <meta>
            <field>text</field>
        </meta>
        <struct>
            <sfield1>text</sfield1>
            <sfield2>text</sfield2>
            <substruct1>
                <ss1field>text</ss1field>
            </substruct1>
            <substruct2>
                <ss2field1>text</ss2field1>
                <ss2field2>004i</ss2field2>
            </substruct2>
            <substruct2>
                <ss2field1>text</ss2field1>
                <ss2field2>0005</ss2field2>
            </substruct2>
        </struct>
    </object>
</message>

你写的XSLT代码报错了，错误信息是：

A sequence of more than one item is not allowed as the second argument of contains() ("0001", "002i", ...)

错误原因 #

你把问题复杂化了：

• 定义的$condition变量把所有ss2field2的处理结果拼接成了一串文本，根本没法对应单个字段
• 调用模板时把所有//substruct2/ss2field2节点序列传给param.target，而contains()的第二个参数只能是单个字符串，不能是节点序列，这直接触发了报错
• 整个自定义模板value-to-replace完全没必要，完全可以直接在匹配节点的模板里处理逻辑

正确的XSLT写法 #

用XSLT的身份模板复制所有节点，然后专门匹配需要修改的ss2field2节点，直接判断处理即可：

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
    <xsl:output method="xml" omit-xml-declaration="yes" indent="yes"/>
    
    <!-- 身份模板：复制所有节点和属性 -->
    <xsl:template match="@*|node()">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
    </xsl:template>
    
    <!-- 匹配目标字段，处理逻辑 -->
    <xsl:template match="message/object/struct/substruct2/ss2field2">
        <xsl:copy>
            <xsl:choose>
                <xsl:when test="ends-with(., 'i')">
                    <xsl:value-of select="concat('0', .)"/>
                </xsl:when>
                <xsl:otherwise>
                    <xsl:value-of select="."/>
                </xsl:otherwise>
            </xsl:choose>
        </xsl:copy>
    </xsl:template>
</xsl:stylesheet>

转换后的结果XML #

<message>
    <object>
        <meta>
            <field>text</field>
        </meta>
        <struct>
            <sfield1>text</sfield1>
            <sfield2>text</sfield2>
            <substruct1>
                <ss1field>text</ss1field>
            </substruct1>
            <substruct2>
                <ss2field1>text</ss2field1>
                <ss2field2>0001</ss2field2>
            </substruct2>
            <substruct2>
                <ss2field1>text</ss2field1>
                <ss2field2>0002i</ss2field2>
            </substruct2>
            <substruct2>
                <ss2field1>text</ss2field1>
                <ss2field2>0003</ss2field2>
            </substruct2>
        </struct>
    </object>
    <object>
        <meta>
            <field>text</field>
        </meta>
        <struct>
            <sfield1>text</sfield1>
            <sfield2>text</sfield2>
            <substruct1>
                <ss1field>text</ss1field>
            </substruct1>
            <substruct2>
                <ss2field1>text</ss2field1>
                <ss2field2>0004i</ss2field2>
            </substruct2>
            <substruct2>
                <ss2field1>text</ss2field1>
                <ss2field2>0005</ss2field2>
            </substruct2>
        </struct>
    </object>
</message>

内容的提问来源于stack exchange，提问作者juankinspain