How to convert BigDecimal to Double in spring-data-mongodb framework

问题:

Spring Data MongoDB mapping by default converts BigDecimal to String. However, I want them to be converted as Double in mongodb. This is required for latter to make queries on this field in mongodb (comparison queries/aggregation queries). How can I reigster my own converter (BigDecimalToDouble / DoubleToBigDecimal) to do this?

回答1:

Here's how you can add your own converters:

<bean id="mongoTemplate" class="org.springframework.data.mongodb.core.MongoTemplate">     <constructor-arg ref="mongoDbFactory"/>     <constructor-arg ref="mappingConverter"/>     <property name="writeConcern">         <util:constant static-field="com.mongodb.WriteConcern.FSYNC_SAFE"/>     </property>     <property name="writeResultChecking">         <util:constant static-field="org.springframework.data.mongodb.core.WriteResultChecking.EXCEPTION"/>     </property> </bean>  <mongo:mapping-converter id="mappingConverter">     <mongo:custom-converters base-package="com.vladmihalcea.**.mongo.converter"/> </mongo:mapping-converter> 

Now your converters would look like:

@Component public class DoubleToBigDecimalConverter implements Converter<Double, BigDecimal> {      @Override     public BigDecimal convert(Double source) {         return new BigDecimal(source);     } }  @Component public class BigDecimalToDoubleConverter implements Converter<BigDecimal, Double> {      @Override     public Double convert(BigDecimal source) {         return source.doubleValue();     } } 

Before adding converter I got:

update test.product query: { _id: 123 } update: { _id: 123, _class: "com.vladmihalcea.mongo.model.Product", name: "Tv", quantity: "10", discount: "12.34", version: 0 } nscanned:0 nupdated:1 upsert:1 keyUpdates:0 locks(micros) w:49328 50ms 

After adding converters:

update test.product query: { _id: 123 } update: { _id: 123, _class: "com.vladmihalcea.mongo.model.Product", name: "Tv", quantity: "10", discount: 12.34, version: 0 } nscanned:0 nupdated:1 upsert:1 keyUpdates:0 locks(micros) w:64689 65ms 

文章来源: How to convert BigDecimal to Double in spring-data-mongodb framework