Question

I’ve got the following XML structure :

    <Article>
         <id>1</id>
         <line>L11</line>
         <line>L12</line>
         <line>L13</line>
     </Article>
    <Article>
         <id>2</id>
         <line>L21</line>
         <line>L22</line>
         <line>L23</line>
     </Article>

I want to use XSLT to iterate over all the lines of only one article at a time so that I can achieve the following structure : (every article is converted into an order, and its lines are converted to line structures in the new structure)

        <orders>
           <order>
              <id>1</id>
              <order_line>L11</order_line>
              <order_line>L12</order_line>
              <order_line>L13</order_line>
            </order>
           <order>
              <id>2</id>
              <order_line>L21</order_line>
              <order_line>L22</order_line>
              <order_line>L23</order_line>
            </order>
        </orders>

Answer 1

With XSLT, try to think of the task at hand as a set of patterns or rules you have to match, and the actions to be taken each time such a pattern is encountered. You can usually let the runtime worry about looping, etc, to discover patterns.

In your specific case, you’ve described two patterns you want special logic. Every time there is the element Article, you wish to apply the rule to change its name to order.
Every time the element line is encountered as a child of Article, replace it with order_line. For any other pattern, you just want to copy the contents as they were in the original document:

<!-- Match element Article, and whenever it's encountered, insert an 'order' element, and copy the contents of Article -->
<xsl:template match="Article">
  <order> <xsl:apply-templates/> </order>
</xsl:template>

<!-- Match element 'line', and whenever it's encountered, insert an 'order_line' element, and copy the contents -->
<xsl:template match="Article/line">
  <order_line> <xsl:apply-templates/> </order_line>
</xsl:template>

<!-- Match any other element we haven't specified explicity, and copy it verbatim -->
<xsl:template match="node()">
  <xsl:copy>
    <xsl:apply-templates/>
  </xsl:copy>
</xsl:template>