How do I set up custom Mongo formatters in Spring? - spring

Question

I've been at this for a few hours and haven't found anyone that's gotten this working yet. I want to persist a BigDecimal object in Mongo, but Mongo doesn't natively support BigDecimal. I followed Spring's docs here but no luck.
From what I can tell Spring isn't injecting my custom converter classes into Mongo when it's writing to the db. Here's what I have done:
My applicationContext-services.xml
...
<!-- Factory bean that creates the Mongo instance -->
<mongo:mongo
host="localhost"
port="1234" />
<mongo:db-factory
dbname="solar"
mongo-ref="mongo"/>
<mongo:mapping-converter>
<mongo:custom-converters>
<mongo:converter>
<bean class="com.mine.BigDecimalReadConverter"/>
</mongo:converter>
<mongo:converter>
<bean class="com.mine..BigDecimalWriteConverter"/>
</mongo:converter>
</mongo:custom-converters>
</mongo:mapping-converter>
<!-- Use this post processor to translate any MongoExceptions thrown in #Repository annotated classes -->
<bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/>
<bean id="mongoDbTest"
class="com.mine.MongoDbTest">
<property name="mongoTemplate">
<ref local="mongoTemplate" />
</property>
</bean>
The error I'm getting is:
java.lang.IllegalArgumentException: Multiple constructors with arguments found in class java.math.BigDecimal! Annotate one with #PreferedConstructor explicitly to select it to be used in persistence operations.
at org.springframework.data.mapping.PreferredConstructorDiscoverer.<init>(PreferredConstructorDiscoverer.java:81)

Answer 1

Try using this for converter support:
<bean id="mappingContext"
class="org.springframework.data.mongodb.core.mapping.MongoMappingContext" lazy-init="true"/>
<bean id="defaultMongoTypeMapper"
class="org.springframework.data.mongodb.core.convert.DefaultMongoTypeMapper" lazy-init="true">
<constructor-arg name="typeKey"><null/></constructor-arg>
</bean>
<bean id="mappingMongoConverter"
class="org.springframework.data.mongodb.core.convert.MappingMongoConverter" lazy-init="true" >
<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" lazy-init="true">
<constructor-arg name="mongoDbFactory" ref="mongoDbFactory" />
<constructor-arg name="mongoConverter" ref="mappingMongoConverter" />
</bean>

Answer 2

Here is how I solved this. The order in which you define the beans matters. So my app.xml that I got it working with is:
<bean id="mappingContext" class="org.springframework.data.document.mongodb.mapping.MongoMappingContext"/>
<bean id="readConverter" class="com.mine.BigDecimalReadConverter"/>
<bean id="writeConverter" class="com.mine.BigDecimalWriteConverter"/>
<mongo:mapping-converter id="mappingConverter">
<mongo:custom-converters>
<mongo:converter ref="readConverter" />
<mongo:converter ref="writeConverter" />
</mongo:custom-converters>
</mongo:mapping-converter>
<!-- Factory bean that creates the Mongo instance -->
<mongo:mongo
host="${${environment}.mongodb.host}"
port="${${environment}.mongodb.port}" />
<mongo:db-factory
dbname="${${environment}.mongodb.databaseName}"
mongo-ref="mongo"/>
<bean id="mongoTemplate" class="org.springframework.data.document.mongodb.MongoTemplate">
<constructor-arg name="mongoDbFactory" ref="mongoDbFactory" />
<constructor-arg name="mongoConverter" ref="mappingConverter"/>
</bean>
<!-- Use this post processor to translate any MongoExceptions thrown in #Repository annotated classes -->
<bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/>