CustomConversions is too liberal in registering "simple types" (asymmetric conversion) [DATAMONGO-268]

[spring-projects-issues]

Harlan Iverson opened DATAMONGO-268 and commented

I have asymmetric converters Converter<DBObject,ThirdPartyClass> for certain entities that I am persisting which do not have a constructor that can be used by the mapper ie. I do no custom Converter<ThirdPartyClass,DBObject>. I also don't have source code to add a @PersistenceConstructor because the classes I am persisting are 3rd party. After stepping through the source code, I've determined that this part of CustomConversions is too liberal, and causing my error:

	private void register(ConvertiblePair pair) {

		if (isMongoBasicType(pair.getSourceType())) {
			readingPairs.add(pair);
			customSimpleTypes.add(pair.getTargetType());
		}

		if (isMongoBasicType(pair.getTargetType())) {
			writingPairs.add(pair);
			customSimpleTypes.add(pair.getSourceType());
		}
	}

customSimpleTypes is then given to the SimpleTypeHolder (still in CustomConversions):

this.simpleTypeHolder = new SimpleTypeHolder(customSimpleTypes, MongoSimpleTypes.HOLDER);

And eventually is determined to be a simple type inside AbstractMappingContext/ AbstractPersistentProperty.

It seems that because my custom entity is a target type it is considered a simple type, and it is left as-is when attempting to write to to Mongo, which fails:

java.lang.IllegalArgumentException: can't serialize class com.example.ThirdPartyClass
	at org.bson.BSONEncoder._putObjectField(BSONEncoder.java:234)
	at org.bson.BSONEncoder.putObject(BSONEncoder.java:140)
	at org.bson.BSONEncoder.putObject(BSONEncoder.java:86)
	at com.mongodb.OutMessage.putObject(OutMessage.java:190)
	at com.mongodb.DBApiLayer$MyCollection.insert(DBApiLayer.java:253)
	at com.mongodb.DBApiLayer$MyCollection.insert(DBApiLayer.java:217)
	at com.mongodb.DBCollection.insert(DBCollection.java:87)
	at org.springframework.data.mongodb.core.MongoTemplate$10.doInCollection(MongoTemplate.java:669)
	at org.springframework.data.mongodb.core.MongoTemplate.execute(MongoTemplate.java:329)
	at org.springframework.data.mongodb.core.MongoTemplate.insertDBObject(MongoTemplate.java:665)
	at org.springframework.data.mongodb.core.MongoTemplate.doInsert(MongoTemplate.java:571)
	at org.springframework.data.mongodb.core.MongoTemplate.insert(MongoTemplate.java:530)
	at _________
	at _________
	at _________(_____Test.java:71)
	at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
	at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:82)
	at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:240)
	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:180)

I would expect that MappingMongoConverter writes the object normally (ie. handles converting the bean to a DBObject automatically) if there is no Converter<ThirdPartyClass,DBObject> converter

---

Affects: 1.0 M4

Attachments:

• mylyn-context.zip (37.32 kB)

[spring-projects-issues]

Harlan Iverson commented

I forgot to mention, my Converter<DBOject,ThirdPartyClass> is implemented pretty simply:

public class DBObjectToSFSEvent implements Converter<DBObject, SFSEvent>, ApplicationContextAware {

  ApplicationContext appContext;
  
  public void setApplicationContext(ApplicationContext appContext) throws BeansException {
    this.appContext = appContext;
  }

  public SFSEvent convert(DBObject s) {
    MappingMongoConverter mappingConv = appContext.getBean(MappingMongoConverter.class);
 
    String extracted = (String)s.get("extracted");
    Map<String, Object> args = mappingConv.read(Map.class, (DBObject)s.get("args"));

    ThirdPartyClass obj = new SFSEvent(extracted, args);
    return obj;
    
  } 
}

[spring-projects-issues]

Oliver Drotbohm commented

Fixed and will be available in tonight's snapshot. We now consider types to be simple if a writing converter is registered as this implies we don't need to build up mapping metadata and entirely hand processing to the converter

[spring-projects-issues]

Harlan Iverson commented

That makes sense, and it did the trick. Thanks again!