Wrong/Misleading error report and error handling when reading erroneous groups

[g0dkar]

Hi! I was developing something using wro4j and noted that it started giving me this exception:

Jul 29, 2014 12:37:16 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [default] in context with path [] threw exception [Filter execution threw an exception] with root cause
java.lang.ClassNotFoundException: groovy.lang.GroovyShell
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
    at ro.isdc.wro.extensions.model.factory.GroovyModelFactory.create(GroovyModelFactory.java:64)
    at ro.isdc.wro.extensions.model.factory.GroovyModelFactory.create(GroovyModelFactory.java:42)
    at ro.isdc.wro.model.factory.LazyWroModelFactoryDecorator.create(LazyWroModelFactoryDecorator.java:28)
    [...]

After a while trying to figure it out, I turned on WRO's debug option and found out the real error was this one:

00:37:16,388 DEBUG [SmartWroModelFactory] [FAIL] creating model... will try another factory: {}
org.xml.sax.SAXParseException; cvc-id.2: There are multiple occurrences of ID value 'user-list'.
    at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:203)
    at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.error(ErrorHandlerWrapper.java:134)
    at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:437)
    at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:368)
    at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:325)
    at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator$XSIErrorReporter.reportError(XMLSchemaValidator.java:458)
    at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.reportSchemaError(XMLSchemaValidator.java:3237)
    at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.processOneAttribute(XMLSchemaValidator.java:2832)
    at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.processAttributes(XMLSchemaValidator.java:2769)
    at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.handleStartElement(XMLSchemaValidator.java:2056)
    at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.startElement(XMLSchemaValidator.java:746)
    at com.sun.org.apache.xerces.internal.jaxp.validation.DOMValidatorHelper.beginNode(DOMValidatorHelper.java:277)
    at com.sun.org.apache.xerces.internal.jaxp.validation.DOMValidatorHelper.validate(DOMValidatorHelper.java:244)
    at com.sun.org.apache.xerces.internal.jaxp.validation.DOMValidatorHelper.validate(DOMValidatorHelper.java:190)
    at com.sun.org.apache.xerces.internal.jaxp.validation.ValidatorImpl.validate(ValidatorImpl.java:109)
    at javax.xml.validation.Validator.validate(Validator.java:124)
    at ro.isdc.wro.model.factory.XmlModelFactory.validate(XmlModelFactory.java:215)
    at ro.isdc.wro.model.factory.XmlModelFactory.createDocument(XmlModelFactory.java:199)
    at ro.isdc.wro.model.factory.XmlModelFactory.create(XmlModelFactory.java:167)
    at ro.isdc.wro.model.factory.XmlModelFactory.create(XmlModelFactory.java:56)
    [...]

Meaning the XML itself is invalid, having two <group> tags with the same name - but the error thrown by wro was about not being able to find Groovy o_O

It doesn't fail there because at SmartWroModelFactory:195 you expect a WroRuntimeException, which in turn is never expected/thrown at XmlModelFactory:215. God (and prob you, hehe) knows why this ends up with a "GroovyShell not found" exception :P

A quick solution would be to change it to:

try {
    schema.newValidator().validate(new DOMSource(document));
} catch (SAXParseException spe) {
    throw new WroRuntimeException("Invalid wro.xml, please check it for errors like repeated ID's, malformed XML or something like that", spe);
}

Last but not least, congrats for maintaining this amazing project! It really grown into something incredibly useful!

[alexo]

Yeah, the SmartWroModelFactory is not so smart after all :)... I would gladly deprecate this feature and would keep things simpler: less is more. Some of the features cause more problems than the benefit they bring....