答
FreeMarker template error:
The following has evaluated to null or missing:
==> questAnsVo.answer [in template "product/product_detail.ftl" at line 141, column 58]
Tip: If the failing expression is known to be legally null/missing, either specify a default value with myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing. (These only cover the last step of the expression; to cover the whole expression, use parenthessis: (myOptionVar.foo)!myDefault, (myOptionVar.foo)??
The failing instruction (FTL stack trace):
----------
==> #if questAnsVo.answer.hfcontent?lengt... [in template "product/product_detail.ftl" at line 141, column 53]
----------
Java stack trace (for programmers):
----------
freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]
at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:98)
at freemarker.core.UnexpectedTypeException.newDesciptionBuilder(UnexpectedTypeException.java:41)
at freemarker.core.UnexpectedTypeException.(UnexpectedTypeException.java:24)
at freemarker.core.Dot._eval(Dot.java:81)
at freemarker.core.Expression.eval(Expression.java:111)
at freemarker.core.Expression.evalAndCoerceToString(Expression.java:115)
at freemarker.core.StringBuiltins$StringBuiltIn._eval(StringBuiltins.java:87)
at freemarker.core.Expression.eval(Expression.java:111)
at freemarker.core.EvalUtil.compare(EvalUtil.java:146)
at freemarker.core.ComparisonExpression.evalToBoolean(ComparisonExpression.java:103)
at freemarker.core.IfBlock.accept(IfBlock.java:82)
at freemarker.core.Environment.visit(Environment.java:265)
at freemarker.core.MixedContent.accept(MixedContent.java:93)
at freemarker.core.Environment.visitByHiddingParent(Environment.java:286)
at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:193)
at freemarker.core.Environment.visitIteratorBlock(Environment.java:509)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:103)
at freemarker.core.Environment.visitByHiddingParent(Environment.java:286)
at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:86)
at freemarker.core.Environment.visit(Environment.java:265)
at freemarker.core.MixedContent.accept(MixedContent.java:93)
at freemarker.core.Environment.visit(Environment.java:265)
at freemarker.core.Environment.process(Environment.java:243)
at freemarker.template.Template.process(Template.java:277)
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.processTemplate(FreeMarkerView.java:366)
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.doRender(FreeMarkerView.java:283)
at org.springframework.web.servlet.view.freemarker.FreeMarkerView.renderMergedTemplateModel(FreeMarkerView.java:233)
at org.springframework.web.servlet.view.AbstractTemplateView.renderMergedOutputModel(AbstractTemplateView.java:167)
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:250)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1047)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:817)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:669)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:574)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:748)
