Persisting Objects containing Objects with spring-data-mongodb

问题

Below is a follow-up question to Question 13832188:

I'm using spring-data-mongodb version 1.1.1.RELEASE. I am able to persist an object if all the member variables are primitive types, even if the names of the @PersistenceConstructor arguments don't match exactly the names of the member variables by using the @Field and @Value annotations.

However, I get a MappingInstantiationException when I try to persist objects that contain other objects. My questions:

• Is this a bug in spring-data-mongodb or am I doing something wrong?
• What needs to change so that I can properly persist objects containing objects?

.

org.springframework.data.mapping.model.MappingInstantiationException: Could not instantiate bean class [com.recorder.TestRecorder2$ObjectContainer]: Illegal arguments for constructor; nested exception is java.lang.IllegalArgumentException: argument type mismatch
    at org.springframework.data.convert.ReflectionEntityInstantiator.createInstance(ReflectionEntityInstantiator.java:77)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:229)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:209)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:173)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:169)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:72)
    at org.springframework.data.mongodb.core.MongoTemplate$ReadDbObjectCallback.doWith(MongoTemplate.java:1820)
    at org.springframework.data.mongodb.core.MongoTemplate.executeFindMultiInternal(MongoTemplate.java:1542)
    at org.springframework.data.mongodb.core.MongoTemplate.findAll(MongoTemplate.java:1064)
    at com.recorder.TestRecorder2.testObjectContainer(RecorderTest2.java:63)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.recorder.TestRecorder2$ObjectContainer]: Illegal arguments for constructor; nested exception is java.lang.IllegalArgumentException: argument type mismatch
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:158)
    at org.springframework.data.convert.ReflectionEntityInstantiator.createInstance(ReflectionEntityInstantiator.java:75)
    ... 34 more
Caused by: java.lang.IllegalArgumentException: argument type mismatch
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:147)
    ... 35 more

My PrimitiveContainer and ObjectContainer classes are listed below:

@Document
class PrimitiveContainer {

    @Field("property") 
    private final int m_property;

    @PersistenceConstructor
    public PrimitiveContainer(@Value("#root.property") int a_property) {
        m_property = a_property;
    }

    public int property() {
        return m_property;
    }
}

@Document
class ObjectContainer {

    @Field("property") 
    private final PrimitiveContainer m_property;

    @PersistenceConstructor
    public ObjectContainer(@Value("#root.property") PrimitiveContainer a_property) {
        m_property = a_property;
    }

    public PrimitiveContainer property() {
        return m_property;
    }
}

---

**UPDATE: ** Curiously, changing the string in the @Field annotation to something other than "property" or removing the @Field annotation entirely for the ObjectContainer m_property allows spring-data-mongo-db to property re-instantiate my persisted ObjectContainer class. I don't understand why this works. Anyone have any ideas?

回答1:

You seem to have found a bug. The value resulting from the first Spel expression evaluation is a DBObject and not actually translated into the parameter type. I've already have some code here locally that fixes that. Would you mind creating a ticket against Spring Data MongoDB to file this as a bug?

来源：https://stackoverflow.com/questions/13854753/persisting-objects-containing-objects-with-spring-data-mongodb