spring data - Spring Data MongoDB Remove _class field

Spring Data MongoDB Remove _class Column

Posted on September 12, 2012 ,     Last modified : April 6, 2013

By mkyong

By default, SpringData’s MappingMongoConverter add an extra “_class” column for every object saved in MongoDB. For example,

public class User {
 
	String username;
	String password;
 
	//...getters and setters
}

Save it

    MongoOperations mongoOperation = (MongoOperations)ctx.getBean("mongoTemplate");	
    User user = new User("mkyong", "password123");
    mongoOperation.save(user, "users");

Result

> db.users.find()
{ 
	"_class" : "com.mkyong.user.User", 
	"_id" : ObjectId("5050aef830041f24ff2bd16e"), 
	"password" : "new password", "username" : "mkyong" 
}

SpringData created this extra “_class” for a reason. To remove this extra “_class“, override the MappingMongoConverter, and passing a new DefaultMongoTypeMapper(null).

Here we show you how to remove the _class in annotation or XML way.

1. Annotation

@Configuration
public class SpringMongoConfig{
 
  public @Bean
  MongoDbFactory mongoDbFactory() throws Exception {
	return new SimpleMongoDbFactory(new Mongo(), "database");
  }
 
  public @Bean
  MongoTemplate mongoTemplate() throws Exception {
 
	//remove _class
	MappingMongoConverter converter = 
		new MappingMongoConverter(mongoDbFactory(), new MongoMappingContext());
	converter.setTypeMapper(new DefaultMongoTypeMapper(null));
 
	MongoTemplate mongoTemplate = new MongoTemplate(mongoDbFactory(), converter);
 
	return mongoTemplate;
 
  }
 
}

2. XML

Same thing, but in XML file.

<mongo:mongo host="localhost" port="27017" />
<mongo:db-factory dbname="database" />
 
 <bean id="mappingContext"
	class="org.springframework.data.mongodb.core.mapping.MongoMappingContext" />
 
 <bean id="defaultMongoTypeMapper"
	class="org.springframework.data.mongodb.core.convert.DefaultMongoTypeMapper">
	<constructor-arg name="typeKey"><null/></constructor-arg>
 </bean>
 
 <bean id="mappingMongoConverter"
	class="org.springframework.data.mongodb.core.convert.MappingMongoConverter">
	<constructor-arg name="mongoDbFactory" ref="mongoDbFactory" />
	<constructor-arg name="mappingContext" ref="mappingContext" />
	<property name="typeMapper" ref="defaultMongoTypeMapper" />
 </bean>
 
 <bean id="mongoTemplate" class="org.springframework.data.mongodb.core.MongoTemplate">
	<constructor-arg name="mongoDbFactory" ref="mongoDbFactory" />
	<constructor-arg name="mongoConverter" ref="mappingMongoConverter" />
 </bean>

3. Test it Again

Save it again, the “_class” is gone.

> db.users.find()
{ 
	"_id" : ObjectId("random code"), 
	"password" : "new password", "username" : "mkyong" 
}

References

1. StackOverflow – MappingMongoConverter remove _class
2. Spring Forum – MappingMongoConverter remove _class

출처 - http://www.mkyong.com/mongodb/spring-data-mongodb-remove-_class-column/