如何使用XML属性的最大子属性更新XML属性节点？

Question

考虑以下XML：

<?xml version="1.0"?>
<sportsClass>
    <pupils>
        <pupil name="Adam" highestJump="">
            <jump height="4"/>
            <jump height="1"/>
        </pupil>
        <pupil name="Berta" highestJump="">
            <jump height="4"/>
            <jump height="7"/>
        </pupil>
        <pupil name="Caesar" highestJump="">
            <jump height="1"/>
            <jump height="2"/>
        </pupil>
        <pupil name="Doris" highestJump="">
            <jump height="5"/>
            <jump height="5"/>
        </pupil>
    </pupils>
</sportsClass>

如何使用xmlstarlet填充highestJump属性节点各自的最大height值？

Answer 1

这个问题包括两个子问题：

找出最大值

xmlstarlet没有max()函数，因此我们必须找到一种方法：

cat jumps.xml | \
xmlstarlet select -t -v "//pupil/jump[not(@height <= following-sibling::jump/@height) and not(@height < preceding-sibling::jump/@height)]/@height"

注意<=和< --如果有多个最大值，则只会取最后一个最大值。

结果：

4
7
2
5

更新属性

定值实践

cat jumps.xml | xmlstarlet edit --update //pupil/@highestJump -v "Hahahaha"

...writes Hahahaha对每个highestJump属性。

简单XPath

注意:用于替换的XPath

• 相对于所选属性(因此.是属性本身)，
• 必须用例如包装。string()对

有影响

所以：

cat jumps.xml | xmlstarlet edit --update //pupil/@highestJump -x "string(../@name)"

...gives (简称)：

<pupil name="Adam" highestJump="Adam">
<pupil name="Berta" highestJump="Berta">
<pupil name="Caesar" highestJump="Caesar">
<pupil name="Doris" highestJump="Doris">

把两者结合起来

cat jumps.xml | xmlstarlet edit --update //pupil/@highestJump -x "string(../jump[not(@height <= following-sibling::jump/@height) and not(@height < preceding-sibling::jump/@height)]/@height)"

...gives...

<?xml version="1.0"?>
<sportsClass>
  <pupils>
    <pupil name="Adam" highestJump="4">
      <jump height="4"/>
      <jump height="1"/>
    </pupil>
    <pupil name="Berta" highestJump="7">
      <jump height="4"/>
      <jump height="7"/>
    </pupil>
    <pupil name="Caesar" highestJump="2">
      <jump height="1"/>
      <jump height="2"/>
    </pupil>
    <pupil name="Doris" highestJump="5">
      <jump height="5"/>
      <jump height="5"/>
    </pupil>
  </pupils>
</sportsClass>