Bobo Bobo - 3 months ago 18
JSON Question

how to configure spring mvc 3 to not return "null" object in json response?

a sample of json response looks like this:

{"publicId":"123","status":null,"partner":null,"description":null}


It would be nice to truncate out all null objects in the response. In this case, the response would become
{"publicId":"123"}
.

Any advice? Thanks!

P.S: I think I can do that in Jersey. Also I believe they both use Jackson as the JSON processer.

Added Later:
My configuration:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">

<!-- Scans the classpath of this application for @Components to deploy as beans -->
<context:component-scan base-package="com.SomeCompany.web" />

<!-- Application Message Bundle -->
<bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
<property name="basename" value="/WEB-INF/messages/messages" />
<property name="cacheSeconds" value="0" />
</bean>

<!-- Configures Spring MVC -->
<import resource="mvc-config.xml" />




<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

<!-- Configures the @Controller programming model -->
<mvc:annotation-driven />

<!-- Forwards requests to the "/" resource to the "welcome" view -->
<!--<mvc:view-controller path="/" view-name="welcome"/>-->

<!-- Configures Handler Interceptors -->
<mvc:interceptors>
<!-- Changes the locale when a 'locale' request parameter is sent; e.g. /?locale=de -->
<bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor" />
</mvc:interceptors>

<!-- Saves a locale change using a cookie -->
<bean id="localeResolver" class="org.springframework.web.servlet.i18n.CookieLocaleResolver" />

<!--<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
<property name="mediaTypes">
<map>
<entry key="atom" value="application/atom+xml"/>
<entry key="html" value="text/html"/>
<entry key="json" value="application/json"/>
<entry key="xml" value="text/xml"/>
</map>
</property>
<property name="viewResolvers">
<list>
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/"/>
<property name="suffix" value=".jsp"/>
</bean>
</list>
</property>
<property name="defaultViews">
<list>
<bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" />
<bean class="org.springframework.web.servlet.view.xml.MarshallingView" >
<property name="marshaller">
<bean class="org.springframework.oxm.jaxb.Jaxb2Marshaller" />
</property>
</bean>
</list>
</property>
</bean>
-->
<!-- Resolves view names to protected .jsp resources within the /WEB-INF/views directory -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/"/>
<property name="suffix" value=".jsp"/>
</bean>


My code:

@Controller
public class SomeController {
@RequestMapping(value = "/xyz", method = {RequestMethod.GET, RequestMethod.HEAD},
headers = {"x-requested-with=XMLHttpRequest","Accept=application/json"}, params = "!closed")
public @ResponseBody
List<AbcTO> getStuff(
.......
}
}

Answer

Yes, you can do this for individual classes by annotating them with @JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL) or you can do it across the board by configuring your ObjectMapper, setting the serialization inclusion to JsonSerialize.Inclusion.NON_NULL.

Here is some info from the Jackson FAQ: http://wiki.fasterxml.com/JacksonAnnotationSerializeNulls.

Annotating the classes is straightforward, but configuring the ObjectMapper serialization config slightly trickier. There is some specific info on doing the latter here.