Map<String, Object> does not serialize propperly

[azlists]

Hi 

I'm trying to save an object that contains a Map<String,Object>. 

The values of the Map can be of different types.

Serialization does not work when the values in the Map are complex Objects (if I remember correctly simple types work properly). 

How can I have morphia serialize this Map properly ? 

I want my Map to be able to store arbitrary object types, and different types can be stored in the same Map... 

Heres' my code example and the exception thrown : 

@Entity

public class TestWithMap {

@Id

private ObjectId id;

private String myProp1;

private Map<String, Object> myMap;

public TestWithMap(ObjectId id, String myProp1, Map<String, Object> myMap) {

super();

this.id = id;

this.myProp1 = myProp1;

this.myMap = myMap;

}

/**

* @return the id

*/

public ObjectId getId() {

return id;

}

/**

* @param id the id to set

*/

public void setId(ObjectId id) {

this.id = id;

}

/**

* @return the myProp1

*/

public String getMyProp1() {

return myProp1;

}

/**

* @param myProp1 the myProp1 to set

*/

public void setMyProp1(String myProp1) {

this.myProp1 = myProp1;

}

/**

* @return the myMap

*/

public Map<String, Object> getMyMap() {

return myMap;

}

/**

* @param myMap the myMap to set

*/

public void setMyMap(Map<String, Object> myMap) {

this.myMap = myMap;

}

}

public class LogEntry {

public static enum SEVERITY { NORMAL, SEVERE, WARN, FATAL};

private String message;

private Timestamp time;

private SEVERITY severity;

public LogEntry(){}

public LogEntry(String message, Timestamp time, SEVERITY severity) {

super();

this.message = message;

this.time = time;

this.severity = severity;

}

/**

* @return the message

*/

public String getMessage() {

return message;

}

/**

* @param message the message to set

*/

public void setMessage(String message) {

this.message = message;

}

/**

* @return the time

*/

public Timestamp getTime() {

return time;

}

/**

* @param time the time to set

*/

public void setTime(Timestamp time) {

this.time = time;

}

/**

* @return the severity

*/

public SEVERITY getSeverity() {

return severity;

}

/**

* @param severity the severity to set

*/

public void setSeverity(SEVERITY severity) {

this.severity = severity;

}

}

//here's how its saved

TestWithMapDao dao = new TestWithMapDaoMorph(TestWithMap.class, getDatastore());

ObjectId oid = new ObjectId();

Map<String, Object> theMap = new HashMap<String, Object>();

theMap.put("fookey", "foovalue");

theMap.put("complxObj", new LogEntry(System.currentTimeMillis(), "hey im the complex object", PRIORITY.important));

TestWithMap twm = new TestWithMap(oid, "i have a map", theMap);

dao.save(twm);

//and the exception :

java.lang.IllegalArgumentException: can't serialize class foo.bar.LogEntry

at org.bson.BasicBSONEncoder._putObjectField(BasicBSONEncoder.java:284)

at org.bson.BasicBSONEncoder.putMap(BasicBSONEncoder.java:324)

at org.bson.BasicBSONEncoder._putObjectField(BasicBSONEncoder.java:246)

at org.bson.BasicBSONEncoder.putObject(BasicBSONEncoder.java:185)

at org.bson.BasicBSONEncoder.putObject(BasicBSONEncoder.java:131)

at com.mongodb.DefaultDBEncoder.writeObject(DefaultDBEncoder.java:33)

at com.mongodb.BSONBinaryWriter.encodeDocument(BSONBinaryWriter.java:339)

at com.mongodb.InsertCommandMessage.writeTheWrites(InsertCommandMessage.java:45)

at com.mongodb.InsertCommandMessage.writeTheWrites(InsertCommandMessage.java:23)

at com.mongodb.BaseWriteCommandMessage.encodeMessageBody(BaseWriteCommandMessage.java:69)

at com.mongodb.BaseWriteCommandMessage.encodeMessageBody(BaseWriteCommandMessage.java:23)

at com.mongodb.RequestMessage.encode(RequestMessage.java:66)

at com.mongodb.BaseWriteCommandMessage.encode(BaseWriteCommandMessage.java:53)

at com.mongodb.DBCollectionImpl.sendWriteCommandMessage(DBCollectionImpl.java:471)

at com.mongodb.DBCollectionImpl.writeWithCommandProtocol(DBCollectionImpl.java:425)

at com.mongodb.DBCollectionImpl.insertWithCommandProtocol(DBCollectionImpl.java:385)

at com.mongodb.DBCollectionImpl.insert(DBCollectionImpl.java:186)

at com.mongodb.DBCollectionImpl.insert(DBCollectionImpl.java:165)

at com.mongodb.DBCollection.insert(DBCollection.java:161)

at com.mongodb.DBCollection.insert(DBCollection.java:107)

at com.mongodb.DBCollection.save(DBCollection.java:966)

at org.mongodb.morphia.DatastoreImpl.save(DatastoreImpl.java:949)

at org.mongodb.morphia.DatastoreImpl.save(DatastoreImpl.java:1013)

at org.mongodb.morphia.DatastoreImpl.save(DatastoreImpl.java:1000)

at org.mongodb.morphia.dao.BasicDAO.save(BasicDAO.java:130)

at foo.bar.Test.testObjectWithMap(Test.java:64)

It appears to me that Morphia simply bypasses the serialization of the values of the Map because the are declared as being of type Object.

Is there any way to have Morphia determine the actual Type of the underlying object at saving time ?

How can I have my map of arbitrary objects stored properly (without having to wrap the values of the Map inside an intermediary object) ?

Thank you ! 

 

[Justin Lee]

Put @Embedded on LogEntry and see what happens.  I think what's happening is that morphia doesn't know what that type is and so just pass it on to the driver which tries to serialize in to bson and fails.  Annotating it will tell morphia to handle that mapping before the driver gets a hold of it.

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[azlists]

 Thank you for your answer. 

Annotating LogEntry with @Embedded did not work. I still get the exact same error. 

Did I spot a bug ? 

From my understanding of morphia, this should be supported no ? 

Thanks again for you feedback. 

[azlists]

Sorry if this message appears multiple time. I've had troubles with google groups.

I've been debugging this a little further and it seems that the LogEntry in the Map is passed to the passthrough converter for some reason. and therefore added "as is" to the DBObject created by Morphia. 

Here is the stack trace up to the point PassthroughConverter is selected : 

Thread [main] (Suspended (breakpoint at line 200 in DefaultConverters))

DefaultConverters.getEncoder(Class) line: 200

DefaultConverters.encode(Class, Object) line: 236

DefaultConverters.encode(Object) line: 232

MapOfValuesConverter.encode(Object, MappedField) line: 62

DefaultConverters.toDBObject(Object, MappedField, DBObject, MapperOptions) line: 210

ValueMapper.toDBObject(Object, MappedField, DBObject, Map<Object,DBObject>, Mapper) line: 19

Mapper.writeMappedField(DBObject, MappedField, Object, Map<Object,DBObject>) line: 630

Mapper.toDBObject(Object, Map<Object,DBObject>, boolean) line: 541

Mapper.toDBObject(Object, Map<Object,DBObject>) line: 523

DatastoreImpl.entityToDBObj(Object, Map<Object,DBObject>) line: 873

DatastoreImpl.save(DBCollection, T, WriteConcern) line: 939

DatastoreImpl.save(T, WriteConcern) line: 1013

DatastoreImpl.save(T) line: 1000

TestWithMapDaoMorph(BasicDAO).save(T) line: 130

 

Is there a way to force morphia to convert this object if it is annotated with @Embedded ? 

For now it seems the annotation is completely ignored when the object is in a collection.

Thank you for your feedback. 

Alex

[TAN Yee Fan]

What I typically do is to convert the "complex object" into a Map and then store this as the value of the containing Map. Conversion can be achieved using Jackson or some other similar library. Something like:

ObjectMapper mapper = new ObjectMapper(); // Jackson object mapper

ObjectId oid = new ObjectId();

Map<String, Object> theMap = new HashMap<String, Object>();

LogEntry entry = ...
theMap.put("complxObj", mapper.convertValue(entry, LinkedHashMap.class));

TestWithMap twm = new TestWithMap(oid, "i have a map", theMap);

Then the entity can be saved.