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Spring Data, MongoDB, and Java 8

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Spring Data, MongoDB, and Java 8

Utilizing the latest Spring frameworks to convert Java 8 dates inside of MongoDB, simplifying a once difficult conversion task. Great concise NoSQL and Java tutorial.

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While saving an object containing the new Java 8 java.time.LocalDateTime, the following error is thrown:

org.springframework.core.convert.ConverterNotFoundException: 
	No converter found capable of converting 
               from type [java.time.LocalDateTime] to type [java.util.Date] org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.time.LocalDateTime] to type [java.util.Date] 

We are testing:

  1. Spring 4.3.2.RELEASE
  2. Spring Data MongoDB 1.9.2.RELEASE

Is Spring-data supporting the new Java 8 Date APIs (JSR-310)?

1. Spring Data and JSR-310

Yes, Spring-data supports the JSR-310 spec, with a custom convertor – Jsr310Converters, review the following code snippet :

CustomConversions.java

package org.springframework.data.mongodb.core.convert;

public class CustomConversions {

	/**
	 * Creates a new {@link CustomConversions} instance registering the given converters.
	 *
	 * @param converters
	 */
	public CustomConversions(List<?> converters) {

		//...
		List<Object> toRegister = new ArrayList<Object>();

		// Add user provided converters to make sure they can override the defaults
		toRegister.addAll(converters);
		toRegister.add(CustomToStringConverter.INSTANCE);
		toRegister.addAll(MongoConverters.getConvertersToRegister());
		toRegister.addAll(JodaTimeConverters.getConvertersToRegister());
		toRegister.addAll(GeoConverters.getConvertersToRegister());
		toRegister.addAll(Jsr310Converters.getConvertersToRegister());
		toRegister.addAll(ThreeTenBackPortConverters.getConvertersToRegister());

		for (Object c : toRegister) {
			registerConversion(c);
		}

		//...
	}

2. Solution

The above Jsr310Converters will be enabled if you declared a Spring managed bean for MappingMongoConverter and pass as an argument for MongoTemplate. Review the following MongoConfig example:

MongoConfig.java

import org.springframework.data.mongodb.core.convert.MappingMongoConverter;

@Configuration
@ComponentScan(basePackages = {"com.mkyong.db"})
public class MongoConfig {

    //...
	@Autowired
	MongoDbFactory mongoDbFactory;

    @Bean
    public MongoTemplate mongoTemplate() throws Exception {

        MongoTemplate mongoTemplate = new MongoTemplate(mongoDbFactory, getDefaultMongoConverter());
        return mongoTemplate;

    }

    @Bean
    public MappingMongoConverter getDefaultMongoConverter() throws Exception {

        MappingMongoConverter converter = new MappingMongoConverter(
                new DefaultDbRefResolver(mongoDbFactory), new MongoMappingContext());

        return converter;
    }

    //...

}

The MappingMongoConverter extends AbstractMongoConverter, and the AbstractMongoConverter is an InitializingBean. If this declared as a Spring managed bean via @Bean, the afterPropertiesSet() will be fired, and register all the default convertors, including the Jsr310Converters

3. FAQs

If the MappingMongoConverter is not managed by Spring (init with a new keyword like below), you must call the .afterPropertiesSet() manually.

MongoConfig.java

@Configuration
@ComponentScan(basePackages = {"com.mkyong.db"})
public class MongoConfig {

    @Autowired
    MongoDbFactory mongoDbFactory;

    @Bean
    public MongoTemplate mongoTemplate() throws Exception {

        MappingMongoConverter converter = new MappingMongoConverter(
				new DefaultDbRefResolver(mongoDbFactory), new MongoMappingContext());

	    //CALL THIS MANULLY, so that all the default convertors will be registered!
		converter.afterPropertiesSet();

        MongoTemplate mongoTemplate = new MongoTemplate(mongoDbFactory, converter);

        return mongoTemplate;

    }

	//...

References

  1. Github – Custom converters to spring-data-mongodb
  2. Spring IO – MappingMongoConverter JavaDoc
  3. Spring IO – CustomConversions JavaDoc

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Topics:
java ,jvm ,spring data ,mongodb ,nosql ,spring

Published at DZone with permission of Yong Mook Kim, DZone MVB. See the original article here.

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