Sprint Data Mongo RC1 issue querying UUID

[neutrino]

I have been sucesfully querying a Mongo collection where the key is of UUID type. Here is an example:

MongoTemplate().findOne(new Query(Criteria.where("_id").is(userId)),SocialUser .class);

With M5 this was working fine but after switching to RC1 I am always getting a null result from this query. To understand what was going on I enabled MongoDb profiling I can see why the query returns nothing. The query parameter for _id produced by Spring has changed:

WITH M5:

{ "ts" : ISODate("2011-12-16T20:35:44.523Z"), "op" : "query", "ns" : "MyList.SocialUser", "query" : { "_id" : BinData(3,"4tF9oXFLI0OudRiiBU9BWQ==") }, "ntoretur
n" : 1, "nscanned" : 1, "nreturned" : 1, "responseLength" : 305, "millis" : 0, "client" : "10.10.4.99", "user" : "" }

WITH RC1:

{ "ts" : ISODate("2011-12-16T20:37:26.854Z"), "op" : "query", "ns" : "MyList.SocialUser", "query" : { "_id" : { "mostSigBits" : NumberLong("4837793376138809826"
), "leastSigBits" : NumberLong("6431508628474721710") } }, "ntoreturn" : 1, "idhack" : true, "responseLength" : 20, "millis" : 0, "client" : "10.10.4.99", "user
" : "" }

Obviously M5 and RC1 have a significant difference here. I am not sure whether it is a bug or by design but I can't find any documentation or notes about this change.

Why is RC1 passing the UUID parameter like this: { "mostSigBits" : NumberLong("4837793376138809826"
), "leastSigBits" : NumberLong("6431508628474721710") } instead of { "_id" : BinData(3,"4tF9oXFLI0OudRiiBU9BWQ==") } ? How can I adjust my configuration so that RC1 does what M5 was doing?

Thanks,

David

[JeitEmgie]

Also facing this problem,

looking in source code I have found that MongoSimpleTypes has a SUPPORTED_ID_CLASSES collection containing only: ObjectId.class, String.class, BigInteger.class

may be related to the problem ?

[neutrino]

I was able to work around the problem by registering a custom UUID to DBObject converter that returns the UUID object (without converting it). I do not fully understand how the hack works but it does it.

Here is my converter:

public class GenericConverterImplementation implements GenericConverter {

@Override
public Set<ConvertiblePair> getConvertibleTypes() {
Set<ConvertiblePair> pairs = new HashSet<ConvertiblePair>();
pairs.add(new ConvertiblePair(UUID.class, DBObject.class));
pairs.add(new ConvertiblePair(DBObject.class, UUID.class));
return pairs;
}

@Override
public Object convert(Object source, TypeDescriptor sourceType,
TypeDescriptor targetType) {


if (sourceType.getObjectType() == UUID.class && targetType.getObjectType() == DBObject.class)
{
return UUIDHelper.fromJavaToDotNet((UUID)source);
}
if (targetType.getObjectType() == UUID.class)
{
return UUIDHelper.fromDotNetToJava((UUID)source);
}
throw new IllegalArgumentException("Could not find a converter from " + sourceType.getName() + " to " + targetType.getName());
}


}

And here is how I am registering it:

socialMongoTemplate = new MongoTemplate(new SimpleMongoDbFactory("myserver","mydbname"));
GenericConversionService serv = (GenericConversionService)socialMongoTemplate.getC onverter().getConversionService();
ArrayList<GenericConverter> converters = new ArrayList<GenericConverter> ();
converters.add(new GenericConverterImplementation());
CustomConversions conversions = new CustomConversions(converters);((MappingMongoConver ter)socialMongoTemplate.getConverter()).setCustomC onversions(conversions);
serv.addConverter(new GenericConverterImplementation());

(Not the most elegant way of registering it. I am new to Spring and still not familiar with Ioc.)

David

[JeitEmgie]

Registering Converter and not respecting the "contract" to return the correct type is definitively not a solution for me.

We can register converter to/from String like this:

public class UUIDToStringConverter implements Converter<UUID, String> {

	@Override
	public String convert(UUID inUUID) {
		return inUUID.toString();
	}

}

public class UUIDToStringConverter implements Converter<UUID, String> {

	@Override
	public String convert(UUID inUUID) {
		return inUUID.toString().toLowerCase();
	}

}

and register them in the context.xml

<mongo:mapping-converter id="mongoDbConverter">
	<mongo:custom-converters>
		<mongo:converter>
			<bean class="your.package.path.UUIDToStringConverter"/>
		</mongo:converter>
		<mongo:converter>
			<bean class="your.package.path.StringToUUIDConverter"/>
		</mongo:converter>
 	</mongo:custom-converters>
</mongo:mapping-converter>

<bean id="mongoTemplate"  class="org.springframework.data.mongodb.core.MongoTemplate">
	<constructor-arg ref="mongoDbFactory" />
	<constructor-arg ref="mongoDbConverter" />
</bean>

but the field will then be a String not a Binary, subtype UUID…

[Oliver Gierke]

@neutrino: Serializing UUIDs is not supported out of the box, so you have to write your own Converter implementations. If you think it's a feature worth being added feel free to raise a JIRA. Generally the approach JeitEmegie showed should be working.

@JeitEmegie: You could come up with converters of:

public enum UUIDToBinaryConverter implements Converter<UUID, org.bson.types.Binary> {

  INSTANCE;

  @Override
  public String convert(UUID inUUID) {
    return new Binary(inUUID.toString().getBytes());
  }
}

as well as the appropriate invert one if you insist on storing them as binary data. The SUPPORTED_ID_CLASSES is gone in recent versions. It essentially captured the types we ware able to auto-generate. Shouldn't have to do anything with the issue.

[JeitEmgie]

I kept my first option to use UUID stored as String, the need of Binary was just for evaluation purpose, not a requirement…