Provide an optional way to convert from BsonUndefined to null [DATAMONGO-1439]

[spring-projects-issues]

Sylvain LAURENT opened DATAMONGO-1439 and commented

Currently (as of 1.8.2) when reading an "undefined" value from mongo, we have this exception :

org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [org.bson.BsonUndefined] to type [java.math.BigDecimal]
at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound(GenericConversionService.java:313) ~[spring-core-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:195) ~[spring-core-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:176) ~[spring-core-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.getPotentiallyConvertedSimpleRead(MappingMongoConverter.java:822) ~[spring-data-mongodb-1.8.2.RELEASE.jar:na]

It would be nice to have a way of converting sunch BsonUndefined to null out of the box.

For my own usage, I created this converter factory :

@ReadingConverter
public class BsonUndefinedToNullObjectConverterFactory implements ConverterFactory<BsonUndefined, @Nullable Object> {
    @Override
    public <T extends @Nullable Object> Converter<BsonUndefined, T> getConverter(Class<T> targetType) {
        return o -> null;
    }

}

It works, with the small glitch of this warning which I think is not correct for this situation :

WARN o.s.d.m.c.convert.CustomConversions - - Registering converter from class org.bson.BsonUndefined to class java.lang.Object as reading converter although it doesn't convert from a Mongo supported type! You might wanna check you annotation setup at the converter implementation.

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Affects: 1.8.4 (Gosling SR4)

1 votes, 2 watchers

[jkjsanthosh]

@a-cordier why do you close this issue, this converter support has to be added in spring data mongodb by default right?
I have see your team wrote a custom converter and registered in mongomappingconverter. But that is temporary solution only right?