You are here: Popular FormatsXML (Extensible Markup Language) Reader/WriterxfMapExpression Elements (Extract and Literal)Example
Example
The following example illustrates the usage of extract and literal expressions. Consider the following element:
<parent>
<child-A t="A1">A1 text</child-A>
<child-B t="B1">
<gc-Y t="Y1">Y1 text</gc-Y>
<gc-Z t="Z1">Z1 text</gc-Z>
<gc-Z t="Z2">Z2 text</gc-Z>
</child-B>
<child-A t="A2">A2 text</child-A>
<child-B t="B2">
<gc-Z t="Z3">Z3 text</gc-Z>
<gc-Z t="Z4">Z4 text</gc-Z>
</child-B>
</parent>
Let the following mapping rule match the <parent> element above. (Again, we do not specify which elements the mapping rule contains – for the purpose of this example, we only need to know that some of these elements use the expression elements.)
<mapping match="parent">
...
<!-- e1 -->
<extract expr="./child-A"/>
...
<!-- e2 -->
<extract expr="./child-A{1}"/>
...
<!-- e3 -->
<extract expr="./child-A{1}[@t]"/>
...
<!-- e4 -->
<extract expr="./child-B[@t]"/>
...
<!-- e5 -->
<extract expr="./child-B/gc-Y"/>
...
<!-- e6 -->
<extract expr="./child-B/gc-Y[@t]"/>
...
<!-- e7 -->
<extract expr="./child-B{2}/gc-Z{2}[@t]"/>
...
<!-- e8 -->
<extract expr="./child-A{2}"/>
...
<!-- e9 -->
<extract expr="./child-B{2}[@t]"/>
...
<!-- l -->
<literal expr="this is literal data"/>
</mapping
Then:
e1 extracts A1 text.
e2 extracts A1 text.
e3 extracts A1.
e4 extracts B1.
e5 extracts Y1 text.
e6 extracts Y1.
e7 extracts Z4.
e8 extracts A2 text.
e9 extracts B2.
l has the literal value this is literal data.