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javahibernatelambdaj

Hibernate and Lambdaj issue with grouping

I want to perform a tree-grouping from query result set using Lambdaj. Results come from Hibernate.

I can do aggregation successfully, but then code fails on grouping:

List<MyClass> list = myDao.findByProperty(value);

Integer intAvg = avg(list, on(MyClass.class).getIntProperty()); //OK

Group<MyClass> group = group(list, on(MyClass.class).getGroupingStringProperty()); //FAIL

Exception is

ch.lambdaj.util.IntrospectionException: java.lang.NoSuchMethodException: org.example.entityMyClass.-2147483644()
    at ch.lambdaj.util.IntrospectionUtil.getPlainPropertyValue(IntrospectionUtil.java:61)
    at ch.lambdaj.util.IntrospectionUtil.getBooleanPropertyValue(IntrospectionUtil.java:53)
    at ch.lambdaj.util.IntrospectionUtil.getPropertyValue(IntrospectionUtil.java:45)
    at ch.lambdaj.group.StringGroupCondition.getGroupValue(StringGroupCondition.java:41)
    at ch.lambdaj.group.GroupImpl.addItem(GroupImpl.java:28)
    at ch.lambdaj.group.Groups.group(Groups.java:58)
    at ch.lambdaj.group.Groups.group(Groups.java:46)
    at ch.lambdaj.Lambda.group(Lambda.java:1237)
    at org.example.package.Class.method(Class.java:128)
    ...............
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
    at org.apache.coyote.ajp.AjpProcessor.process(AjpProcessor.java:190)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NoSuchMethodException: org.example.entityMyClass.-2147483644()
    at java.lang.Class.getMethod(Class.java:1665)
    at ch.lambdaj.util.IntrospectionUtil.getPlainPropertyValue(IntrospectionUtil.java:59)
    ... 91 more

I tried to do some homework, unsuccessfully for now.

Lambdaj uses cglib to perform proxying. Ivy file provides a cglib-nodep.jar package. Our architecture project features (because of dependency with Hibernate) cglib standard release and asm-all. Please note that, due to company policy, our Ivy dependency file does not allow transitive dependency, and dependencies are decided by the dev team based on the real needs of the projects (so if Hibernate requires a certain version of cglib, we put that dependency into Ivy and mark everything as non-transitive).

So in my project I have <dependency org="com.googlecode.lambdaj" name="lambdaj" rev="2.3.3"/> (transitive true by default) and my architecture project, on which my project depends, has

    <dependency org="org.ow2.asm"                      name="asm-all"                         rev="4.0"            transitive="false"/>
    <dependency org="org.hibernate"                    name="hibernate-core"                  rev="4.1.6.Final"    transitive="false"/>
    <dependency org="org.hibernate"                    name="hibernate-ehcache"               rev="4.1.6.Final"    transitive="false"/>
    <dependency org="org.hibernate"                    name="hibernate-validator"             rev="4.3.0.Final"    transitive="false"/>
    <dependency org="org.hibernate.javax.persistence"  name="hibernate-jpa-2.0-api"           rev="1.0.1.Final"    transitive="false"/>

(and a lot more)

The question is: am I doing something wrong in the code? Is that an issue with Hibernate?

Solution

  • Trivial mistake

    The API must be invoked not as 

    Group<MyClass> group = group(list, on(MyClass.class).getGroupingStringProperty());

    but rather

    Group<MyClass> group = group(list, by(on(MyClass.class).getGroupingStringProperty()));

    Notice group...by syntax