Freemarker DOM attribute check not working - freemarker

Question

I have the following XML
<OS_LINESTATUS LINENUMBER="1" QUANTITY="6" REQUESTNUMBER="598089607" STATUSCODE="LC"/>
<OS_LINESTATUS LINENUMBER="1" QUANTITY="1" REQUESTNUMBER="725772899" STATUSCODE="LC"/>
<OS_LINESTATUS LINENUMBER="1" REQUESTNUMBER="599927622" STATUSCODE="LI"/>
I have the following freemarker template where the xml elements are injected as "elements".
[<#list elements as element>{"primeLineNo":"${element.OS_LINESTATUS.#LINENUMBER}","poLineStatusInfos":[{"poLineStatus":"${element.OS_LINESTATUS.#STATUSCODE}"<#if element.OS_LINESTATUS.#QUANTITY??>,"poLineStatusQuantity":{"measurementValue":"${element.OS_LINESTATUS.#QUANTITY}","unitOfMeasure":"EA"}</#if>}]}<#sep>,</#sep></#list>]}]}}
But this fails at the third line as there is not quantity attribute even though I have put an if condition. Why is the if condition not working?
Following is the stack trace
==> element.OS_LINESTATUS.#QUANTITY [in template "suman-xml-to-xml- orderrequestxform/xml-aggregation/linestatus.ftl" at line 4, column 331]
----
Tip: This XML query result can't be used as string because for that it had to contain exactly 1 XML node, but it contains 0 nodes. That is, the constructing XML query has found no matches.
FTL stack trace ("~" means nesting-related): - Failed at: ${element.OS_LINESTATUS.#QUANTITY} [in template "suman-xml-to- xml-orderrequestxform/xml-aggregation/linestatus.ftl" at line 4, column 329]
Java stack trace (for programmers):
freemarker.core.NonStringException: [... Exception message was already printed; see it above ...]
at freemarker.core.EvalUtil.coerceModelToString(EvalUtil.java:390)
at freemarker.core.Expression.evalAndCoerceToString(Expression.java:82)
at freemarker.core.DollarVariable.accept(DollarVariable.java:41)
at freemarker.core.Environment.visit(Environment.java:324)
at freemarker.core.MixedContent.accept(MixedContent.java:54)
at freemarker.core.Environment.visitByHiddingParent(Environment.java:345)
at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:48)
at freemarker.core.Environment.visit(Environment.java:324)
at freemarker.core.MixedContent.accept(MixedContent.java:54)
at freemarker.core.Environment.visitByHiddingParent(Environment.java:345)
at freemarker.core.IteratorBlock$IterationContext.executeNestedBlockInner(IteratorBlock.java:268)
at freemarker.core.IteratorBlock$IterationContext.executeNestedBlock(IteratorBlock.java:220)
at freemarker.core.IteratorBlock$IterationContext.accept(IteratorBlock.java:194)
at freemarker.core.Environment.visitIteratorBlock(Environment.java:572)
at freemarker.core.IteratorBlock.acceptWithResult(IteratorBlock.java:78)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:64)
at freemarker.core.Environment.visit(Environment.java:324)
at freemarker.core.MixedContent.accept(MixedContent.java:54)
at freemarker.core.Environment.visit(Environment.java:324)
at freemarker.core.Environment.process(Environment.java:302)
at freemarker.template.Template.process(Template.java:325)
at example.aggregation.XmlElementAggregator.output(XmlElementAggregator.java:93)
at example.aggregation.XmlElementAggregator.aggregate(XmlElementAggregator.java:58)
at example.aggregation.XmlElementAggregator.visitAfter(XmlElementAggregator.java:45)
at org.milyn.delivery.sax.SAXHandler.visitAfter(SAXHandler.java:389)
at org.milyn.delivery.sax.SAXHandler.endElement(SAXHandler.java:204)
at org.milyn.delivery.SmooksContentHandler.endElement(SmooksContentHandler.java:96)
at org.apache.xerces.parsers.AbstractSAXParser.endElement(Unknown Source)
at org.apache.xerces.parsers.AbstractXMLDocumentParser.emptyElement(Unknown Source)
at org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.milyn.delivery.sax.SAXParser.parse(SAXParser.java:76)
at org.milyn.delivery.sax.SmooksSAXFilter.doFilter(SmooksSAXFilter.java:86)
at org.milyn.delivery.sax.SmooksSAXFilter.doFilter(SmooksSAXFilter.java:64)
at org.milyn.Smooks._filter(Smooks.java:526)
at org.milyn.Smooks.filterSource(Smooks.java:482)
at example.TransformerBuilder.transform(TransformerBuilder.java:66)
at example.TransformAggregation.main(TransformAggregation.java:31)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

Answer 1

The #if condition works because you are asking if element.OS_LINESTATUS.#QUANTITY exists, which does, as it's a result set of size 0. Use element.OS_LINESTATUS.#QUANTITY[0]?? instead. So that's the tricky about FreeMarker's DOM wrapper, that even queries which find nothing returns something. That's why such a result is #list-able, and more importantly, can be the context of further XPath queries (like element.maybeMissingElement.child never fails, just sometimes gives an empty result set).