FreeMarker template error: The following has evaluated to null or missing: ==> [in template "component://snj2/template/catalog/ProductDetail.ftl" at line 389, column 19] ---- Tip: It's the step after the last dot that caused this error, not those before it. ---- Tip: If the failing expression is known to be legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)?? ---- ---- FTL stack trace ("~" means nesting-related): - Failed at: #if (product.originalImageUrl?string?... [in template "component://snj2/template/catalog/ProductDetail.ftl" at line 389, column 13] ---- Java stack trace (for programmers): ---- freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...] at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:134) at freemarker.core.UnexpectedTypeException.newDesciptionBuilder(UnexpectedTypeException.java:80) at freemarker.core.UnexpectedTypeException.<init>(UnexpectedTypeException.java:43) at freemarker.core.BuiltInsForMultipleTypes$stringBI._eval(BuiltInsForMultipleTypes.java:709) at freemarker.core.Expression.eval(Expression.java:81) at freemarker.core.ExistenceBuiltins$ExistenceBuiltIn.evalMaybeNonexistentTarget(ExistenceBuiltins.java:52) at freemarker.core.ExistenceBuiltins$has_contentBI._eval(ExistenceBuiltins.java:112) at freemarker.core.ExistenceBuiltins$has_contentBI.evalToBoolean(ExistenceBuiltins.java:119) at freemarker.core.AndExpression.evalToBoolean(AndExpression.java:36) at freemarker.core.ParentheticalExpression.evalToBoolean(ParentheticalExpression.java:35) at freemarker.core.IfBlock.accept(IfBlock.java:49) at freemarker.core.Environment.visit(Environment.java:326) at freemarker.core.Environment.visit(Environment.java:332) at freemarker.core.Environment.visit(Environment.java:332) at freemarker.core.Environment.process(Environment.java:305) at org.apache.ofbiz.base.util.template.FreeMarkerWorker.renderTemplate(FreeMarkerWorker.java:263) at org.apache.ofbiz.widget.model.HtmlWidget.renderHtmlTemplate(HtmlWidget.java:167) at org.apache.ofbiz.widget.model.HtmlWidget$HtmlTemplate.renderWidgetString(HtmlWidget.java:216) at org.apache.ofbiz.widget.model.HtmlWidget.renderWidgetString(HtmlWidget.java:140) at org.apache.ofbiz.widget.model.ModelScreenWidget$PlatformSpecific.renderWidgetString(ModelScreenWidget.java:1321) at org.apache.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.apache.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.apache.ofbiz.widget.model.ModelScreen.renderScreenString(ModelScreen.java:164) at org.apache.ofbiz.widget.model.ScreenFactory.renderReferencedScreen(ScreenFactory.java:214) at org.apache.ofbiz.widget.model.ModelScreenWidget$IncludeScreen.renderWidgetString(ModelScreenWidget.java:780) at org.apache.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.apache.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.apache.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.apache.ofbiz.widget.model.ModelScreenWidget$DecoratorSection.renderWidgetString(ModelScreenWidget.java:906) at org.apache.ofbiz.widget.model.ModelScreenWidget$SectionsRenderer.render(ModelScreenWidget.java:127) at org.apache.ofbiz.widget.model.ModelScreenWidget$DecoratorSectionInclude.renderWidgetString(ModelScreenWidget.java:943) at org.apache.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.apache.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.apache.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.apache.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.apache.ofbiz.widget.model.ModelScreen.renderScreenString(ModelScreen.java:164) at org.apache.ofbiz.widget.model.ScreenFactory.renderReferencedScreen(ScreenFactory.java:214) at org.apache.ofbiz.widget.model.ModelScreenWidget$DecoratorScreen.renderWidgetString(ModelScreenWidget.java:860) at org.apache.ofbiz.widget.model.ModelScreenWidget.renderSubWidgetsString(ModelScreenWidget.java:98) at org.apache.ofbiz.widget.model.ModelScreenWidget$Section.renderWidgetString(ModelScreenWidget.java:280) at org.apache.ofbiz.widget.model.ModelScreen.renderScreenString(ModelScreen.java:164) at org.apache.ofbiz.widget.renderer.ScreenRenderer.render(ScreenRenderer.java:136) at org.apache.ofbiz.widget.renderer.ScreenRenderer.render(ScreenRenderer.java:98) at org.apache.ofbiz.widget.renderer.macro.MacroScreenViewHandler.render(MacroScreenViewHandler.java:157) at org.apache.ofbiz.webapp.control.RequestHandler.renderView(RequestHandler.java:1001) at org.apache.ofbiz.webapp.control.RequestHandler.doRequest(RequestHandler.java:653) at org.apache.ofbiz.webapp.control.ControlServlet.doGet(ControlServlet.java:213) at javax.servlet.http.HttpServlet.service(HttpServlet.java:687) at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:720) at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:466) at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:391) at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:318) at org.apache.ofbiz.product.category.CatalogUrlServlet.doGet(CatalogUrlServlet.java:153) at javax.servlet.http.HttpServlet.service(HttpServlet.java:687) at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) at org.apache.ofbiz.webapp.control.ContextFilter.doFilter(ContextFilter.java:324) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) at org.apache.ofbiz.content.content.ContentUrlFilter.doFilter(ContentUrlFilter.java:99) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) at org.apache.ofbiz.product.category.CatalogUrlFilter.doFilter(CatalogUrlFilter.java:338) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:528) at org.apache.coyote.ajp.AbstractAjpProcessor.process(AbstractAjpProcessor.java:873) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:670) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:748)
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Understanding Flight, Second Edition

by David Anderson, Scott Eberhardt,

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Description

Discover how planes get--and stay--airborneNow you can truly master an understanding of the phenomenon of flight. This practical guide is the most intuitive introduction to basic flight mechanics available. Understanding Flight, Second Edition, explains the principles of aeronautics in terms, descriptions, and illustrations that make sense--without complicated mathematics. Updated to include helicopter flight fundamentals and aircraft structures, this aviation classic is required reading for new pilots, students, engineers, and anyone fascinated with flight. Understanding Flight, Second Edition, covers: Physics of flightWing design and configurationStability and controlPropulsionHigh-speed flightPerformance and safetyAerodynamic testingHelicopters and autogyrosAircraft structures and materials

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Product Details

  • McGraw-Hill Professional Brand
  • 9780071626965 ISBN-13:
  • 0071626964 ISBN-10:
  • 0071626964 ISBN-10
  • 9780071626965 ISBN-13
  • New Condition
  • Hardback Media
  • 5 business days Generally Ships in
  • 7.32 in * 0.67 in * 9.17 in Dimensions:
  • 1 lb Weight: