错误 error.GrailsExceptionResolver - 无法引用隐式元素

Question

当我尝试使用 Xstream 封送我的常规域类 Employee 之一时，出现以下错误。 Employee有很多empeeDesiredSkills，分别属于Skill和Employee

这里是相关的Xstream代码

employeeInstance = new Employee();
XStream xstream = new XStream();

Xstream.alias("employee", Employee.class);

String xml = xstream.toXML(employeeInstance);

Employee类将employeeDesiredSkills显式定义为ArrayLists。我不太确定错误消息说的是什么。我只知道“C 开发”是数据库中保存为 EmployeeDesiredSkill 的项目之一

2010-09-21 18:13:13,911 [http-8080-1] ERROR errors.GrailsExceptionResolver  - Cannot    reference implicit element
---- Debugging information ----
implicit-element    : C Development
referencing-element : /employee/employeeDesiredSkills/storedSnapshot/EmployeeDesiredSkill/skill/roleSkills/owner
-------------------------------
com.thoughtworks.xstream.core.AbstractReferenceMarshaller$ReferencedImplicitElementException: Cannot reference implicit element
---- Debugging information ----
implicit-element    : C Development
referencing-element : /employee/employeeDesiredSkills/storedSnapshot/EmployeeDesiredSkill/skill/roleSkills/owner

-------------------------------
    at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:58)
    at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:78)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshallField(AbstractReflectionConverter.java:157)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$2.writeField(AbstractReflectionConverter.java:148)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$2.visit(AbstractReflectionConverter.java:118)
    at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.visitSerializableFields(PureJavaReflectionProvider.java:129)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doMarshal(AbstractReflectionConverter.java:100)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshal(AbstractReflectionConverter.java:58)
    at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:68)
    at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:78)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshallField(AbstractReflectionConverter.java:157)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$2.writeField(AbstractReflectionConverter.java:148)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$2.visit(AbstractReflectionConverter.java:118)
    at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.visitSerializableFields(PureJavaReflectionProvider.java:129)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doMarshal(AbstractReflectionConverter.java:100)

Answer 1

鉴于异常，您的 Employee 元素可能有一个需要在 XStream 对象中显式指定别名的字段。

我无法提供任何具体建议，因为我对您的领域和环境不太了解。但是，您可以尝试弄乱别名，直到一切正常为止。

作为调试方法，您可以尝试使用 XStream 的 omitField() 在所有 Employee 属性上，然后一次删除一个，直到找到哪个一个是造成问题的原因。您可以从那里向下钻取。