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Spring filtering response fields with jackson

I am trying to filter fields in a nested object:
class Response {
// These objects themselves can have many fields within
private final PropA a;
private final PropB b;
#JsonCreator
public Response(PropA a, PropB b) { ... }
}
I'd like a generic 'filter helper' to achieve the above logic. Here is what I have so far (following a similar approach as this project)
public class FilterHelper {
private final ObjectMapper objectMapper;
public FilterHelper(ObjectMapper objectMapper) {
this.objectMapper = objectMapper;
this.objectMapper.addMixIn(Object.class, MyFilterMixin.class);
}
#JsonFilter("myfilter")
public static class MyFilterMixin {
}
private static class MyFilter extends SimpleBeanPropertyFilter {
private final Set<String> properties;
public MyFilter(Set<String> properties) {
super();
this.properties = properties;
}
#Override
public void serializeAsField(final Object pojo, final JsonGenerator jgen, final SerializerProvider provider,
final PropertyWriter writer) throws Exception {
System.out.println("************************** " + writer.getName());
if (properties.contains(writer.getName())) {
writer.serializeAsField(pojo, jgen, provider);
} else if (!jgen.canOmitFields()) {
writer.serializeAsOmittedField(pojo, jgen, provider);
}
}
}
public String filter(T obj, Set<String> fields) {
FilterProvider filterProvider = new SimpleFilterProvider().addFilter("myfilter", new MyFilter(fields));
return objectMapper.writer(filterProvider).writeValueAsString(obj);
}
}
When I hit this endpoint with ?fields=one,two as query parameter I expect to see from a line printed to console for every field within that top level Response object as follows:
******************* a
******************* a1
******************* a2
******************* ..etc
******************* b
******************* b1
******************* b2
******************* ..etc
but I am only seeing output for the top level a and b fields followed by an error before getting a 500 status code from the endpoint:
com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot resolve PropertyFilter with id 'myfilter'; no FilterProvider configured (through reference chain: com.google.common.collect.SingletonImmutableList[0])
It is worth mentioning that I had this working somehow, but it was broken after some changes I don't recall.

Unless you need to provide custom serialization for different fields, you should not be hooking the serializeAsField and instead you should be overriding the #include variant methods:
com.fasterxml.jackson.databind.ser.impl.SimpleBeanPropertyFilter#include(com.fasterxml.jackson.databind.ser.BeanPropertyWriter)
com.fasterxml.jackson.databind.ser.impl.SimpleBeanPropertyFilter#include(com.fasterxml.jackson.databind.ser.PropertyWriter)
as follows:
private static class MyFilter extends SimpleBeanPropertyFilter {
private final Set<String> properties;
public MyFilter(Set<String> properties) {
super();
this.properties = properties;
}
#Override
protected boolean include(BeanPropertyWriter writer) {
return !this.properties.contains(writer.getName());
}
#Override
protected boolean include(PropertyWriter writer) {
return !this.properties.contains(writer.getName());
}
}
There is even a static factory providing a com.fasterxml.jackson.databind.ser.PropertyFilter that filters out a specific set of fields:
com.fasterxml.jackson.databind.ser.impl.SimpleBeanPropertyFilter#serializeAllExcept(java.util.Set<java.lang.String>)
Extra issue
At the filter helper level, you are serializing the filtered object to JSON then deserializing it back (with filtered fields) to an object that you are handing back as the endpoint response.
Solution / Alternative
You can simply omit the intermediary step by just sterilizing the result Response with the filter fields predicate and returning the result JSON as ResponseEntity:
FilterHelper:
#Component
public class FilterHelper {
private final ObjectMapper objectMapper;
#Autowired
public FilterHelper(ObjectMapper objectMapper) {
this.objectMapper = objectMapper;
this.objectMapper.addMixIn(Object.class, MyFilterMixin.class);
}
#JsonFilter("myfilter")
public static class MyFilterMixin {
}
private static class MyFilter extends SimpleBeanPropertyFilter {
private final Set<String> properties;
public MyFilter(Set<String> properties) {
super();
this.properties = properties;
}
#Override
protected boolean include(BeanPropertyWriter writer) {
return !this.properties.contains(writer.getName());
}
#Override
protected boolean include(PropertyWriter writer) {
return !this.properties.contains(writer.getName());
}
}
public String filter(Object dto, Set<String> fields) {
if (fields == null || fields.isEmpty()) {
return "";
}
FilterProvider filterProvider = new SimpleFilterProvider()
.addFilter("myfilter", SimpleBeanPropertyFilter.serializeAllExcept(fields));
try {
return objectMapper.writer(filterProvider).writeValueAsString(dto);
} catch (JsonProcessingException e) {
return "";
}
}
}
Controller:
#GetMapping(value = "/", produces = MediaType.APPLICATION_JSON_VALUE)
#ResponseStatus(OK)
ReponseEntity<String> someEndpoint(#RequestParam(name = "fields") Set<String> fields) {
Response response = getResponseFromSomewhere();
return ResponseEntity.ok(filterHelper.filter(response, fields));
}

Spring Boot JPA - paging and sorting

I am trying to implement pagination to my Spring Data JPA repository in Spring Boot but I am stuck with the following exception when running uni tests:
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.data.domain.Pageable]: Specified class is an interface
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
...
Could someone point out to me what am I missing here? This is my repository:
#Repository
public interface VenueRepository extends PagingAndSortingRepository<Venue, Long> {
public Page<Venue> findAll(Pageable pageable);
}
and controller:
#RestController
#RequestMapping("/venues")
public class VenueController {
#Autowired
private VenueRepository venueRepo;
#RequestMapping(method = RequestMethod.GET)
public ResponseEntity<Page<Venue>> getVenues(Pageable pageable) {
return new ResponseEntity<>(venueRepo.findAll(pageable), HttpStatus.OK);
}
}
and finally my test:
#Test
public void responseOkVenuesTest() throws Exception {
mvc.perform(get("/venues").accept(MediaType.APPLICATION_JSON_VALUE)).andExpect(status().isOk());
}
I spent couple of hours trying to make this work and am running out of ideas. Thank you for any tips!

Change your method getVenues in the way that you can pass the parameters to instantiate a PageRequest instead of passing Pageable :
#RequestMapping(method = RequestMethod.GET)
public ResponseEntity<List<Venue>> getVenues(int from,int to) {
return new ResponseEntity<>(
venueRepo.findAll((new PageRequest(from, to)), HttpStatus.OK).getContent();
}

In addition to #SEY_91's answer you might also like to use the following solution inspired with How to remove redundant Spring MVC method by providing POST-only #Valid? and used in my Spring Boot-driven application for long time.
In short, here is an annotation to annotate controller method parameters:
#Target(PARAMETER)
#Retention(RUNTIME)
public #interface PlainModelAttribute {
}
Now, just a method processor that would scan for parameters annotated with #PlainModelAttribute:
public final class PlainModelAttributeMethodProcessor
extends ModelAttributeMethodProcessor {
private final Map<TypeToken<?>, Converter<? super NativeWebRequest, ?>> index;
private PlainModelAttributeMethodProcessor(final Map<TypeToken<?>, Converter<? super NativeWebRequest, ?>> index) {
super(true);
this.index = index;
}
public static HandlerMethodArgumentResolver plainModelAttributeMethodProcessor(final Map<TypeToken<?>, Converter<? super NativeWebRequest, ?>> index) {
return new PlainModelAttributeMethodProcessor(index);
}
#Override
public boolean supportsParameter(final MethodParameter parameter) {
return parameter.hasParameterAnnotation(PlainModelAttribute.class) || super.supportsParameter(parameter);
}
#Override
protected Object createAttribute(final String attributeName, final MethodParameter parameter, final WebDataBinderFactory binderFactory,
final NativeWebRequest request) {
final TypeToken<?> typeToken = TypeToken.of(parameter.getGenericParameterType());
final Converter<? super NativeWebRequest, ?> converter = index.get(typeToken);
if ( converter == null ) {
throw new IllegalArgumentException("Cannot find a converter for " + typeToken.getType());
}
return converter.convert(request);
}
#Override
protected void bindRequestParameters(final WebDataBinder binder, final NativeWebRequest request) {
final HttpServletRequest servletRequest = request.getNativeRequest(HttpServletRequest.class);
if ( !isSafe(resolve(servletRequest.getMethod())) ) {
((ServletRequestDataBinder) binder).bind(servletRequest);
}
}
private static HttpMethod resolve(final String name) {
return HttpMethod.valueOf(name.toUpperCase());
}
private static boolean isSafe(final HttpMethod method)
throws UnsupportedOperationException {
switch ( method ) {
case GET:
case HEAD:
case OPTIONS:
return true;
case POST:
case PUT:
case PATCH:
case DELETE:
return false;
case TRACE:
throw new UnsupportedOperationException();
default:
throw new AssertionError(method);
}
}
}
I don't really remember, but a resolve() method equivalent should be present in Spring Framework somewhere. Note that I use Google Guava TypeToken in order to let the processor be compatible with generic types (since I use models like IQuery<Foo> and IQuery<Bar> in controllers). Now just register the processor:
#Configuration
#EnableWebMvc
public class MvcConfiguration
extends WebMvcConfigurerAdapter {
#Override
public void addArgumentResolvers(final List<HandlerMethodArgumentResolver> argumentResolvers) {
argumentResolvers.add(createModelAttributeMethodProcessor());
}
private static HandlerMethodArgumentResolver createModelAttributeMethodProcessor() {
return plainModelAttributeMethodProcessor(ImmutableMap.of(pageableTypeToken, MvcConfiguration::toPageable));
}
private static final TypeToken<Pageable> pageableTypeToken = new TypeToken<Pageable>() {
};
private static Pageable toPageable(final WebRequest request) {
return new PageRequest(
ofNullable(request.getParameter("page")).map(Integer::parseInt).orElse(0),
ofNullable(request.getParameter("size")).map(Integer::parseInt).orElse(1)
);
}
}
Here is a web request to a Pageable DTO conversion, and the converter must be registered as an argument resolver. So now it's ready to use:
#RestController
#RequestMapping("/")
public class Controller {
#RequestMapping(method = GET)
public String get(#PlainModelAttribute final Pageable pageable) {
return toStringHelper(pageable)
.add("offset", pageable.getOffset())
.add("pageNumber", pageable.getPageNumber())
.add("pageSize", pageable.getPageSize())
.add("sort", pageable.getSort())
.toString();
}
}
A few examples:
/ ⇒ PageRequest{offset=0, pageNumber=0, pageSize=1, sort=null}
/?page=43 ⇒ PageRequest{offset=43, pageNumber=43, pageSize=1, sort=null}
/?size=32 ⇒ PageRequest{offset=0, pageNumber=0, pageSize=32, sort=null}
/?page=22&size=32 ⇒ PageRequest{offset=704, pageNumber=22, pageSize=32, sort=null}

How can I use Spring REST with MappingJackson2XmlHttpMessageConverter and XSD validation

I'm creating a Spring 4 REST application, using MappingJackson2XmlHttpMessageConverter to convert incoming XML requests to domain objects. Is there any way to apply XSD validation in that process? If not, I think my fallback is to just make the #RequestBody a String, parse and validate it, and then convert it to the domain object. Is there a better approach?

One approach to this may be to write a custom HttpMessageConverter<T> that checks XSD validation (look here for a way to validate XML with XSD) before returning the object.
Suppose that you have the following method in your Controller class:
#RequestMapping(value = "/")
public CustomObject getCustomObject(#RequestParam(value = "id") String id){
return new CustomObject();
}
Then your converter may look like this:
public class CustomObjectConverter implements HttpMessageConverter<CustomObject> {
// a real message converter that will respond to ancillary methods and do the actual work
protected HttpMessageConverter<Object> delegateConverter;
public CustomObjectConverter (HttpMessageConverter<Object> delegate) {
super(delegate, personService);
super.delegateConverter = delegate;
this.employeePhotoBaseUrl = employeePhotoBaseUrl;
}
#Override
public boolean canRead(Class<?> clazz, MediaType mediaType) {
return delegateConverter.canRead(clazz, mediaType) && CustomObject.class.equals(clazz);
}
#Override
public boolean canWrite(Class<?> clazz, MediaType mediaType) {
return delegateConverter.canWrite(clazz, mediaType) && CustomObject.class.equals(clazz);
}
#Override
public List<MediaType> getSupportedMediaTypes() {
return delegateConverter.getSupportedMediaTypes();
}
#Override
public CustomObject read(Class<? extends CustomObject> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException {
return (CustomObject) delegateConverter.read(clazz, inputMessage);
}
#Override
public void write(CustomObject t, MediaType contentType, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException {
if(validationOK)
delegateConverter.write(t, contentType, outputMessage);
else
// You may implement a custom exception handler to return a proper HTTP error code
throw new YourCustomException();
}
}
Remember to configure your new converter. I do this in my configuration class:
#Configuration
#EnableWebMvc
public class RestConfig extends WebMvcConfigurerAdapter {
#Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
// initialize your MappingJackson2XmlHttpMessageConverter
MappingJackson2XmlHttpMessageConverter xmlMessageConverter = xmlMessageConverter();
//Here we add our custom-configured HttpMessageConverters
converters.add(new CustomObjectConverter(xmlMessageConverter));
super.configureMessageConverters(converters);
}
}

Restlet Complex Object to XML serializaton

I have restlet web service which returns response as xml. I'm using Jackson as binder.
below is class I'm returning.
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
public class ApiResponse<T> implements Serializable {
/**
*
*/
private static final long serialVersionUID = -2736991050157565598L;
private int responseCode;
private String reponseMessage;
private List<T> body = new ArrayList<T>();
public int getResponseCode() {
return responseCode;
}
public void setResponseCode(int responseCode) {
this.responseCode = responseCode;
}
public String getReponseMessage() {
return reponseMessage;
}
public void setReponseMessage(String reponseMessage) {
this.reponseMessage = reponseMessage;
}
public List<T> getBody() {
return body;
}
public void setBody(List<T> body) {
this.body = body;
}
}
And below is response of the service. Everything is almost good except that it puts as property names for nested objects the same as parents. It shows body for nested tag names but I expect it to be T template. Any ideas?
<ApiResponse>
<responseCode>1</responseCode>
<reponseMessage />
<body>
<body>
<reportId>1</reportId>
<reportName>name1</reportName>
</body>
<body>
<reportId>2</reportId>
<reportName>name2</reportName>
</body>
</body>
</ApiResponse>

This is the default serialization with Jackson. However you can leverage custom serializer to improve this. This feature allows you to have the hand on the generated content within Jackson for a specific class. You can override the default strategy with your own and configure in a very fine manner what will be created.
Below a sample of such entity that generates content for the class SomeBean:
public class SomeBeanSerializer extends JsonSerializer<SomeBean> {
#Override
public void serialize(SomeBean bean, JsonGenerator jgen,
SerializerProvider provider) throws IOException,
JsonProcessingException {
jgen.writeStartObject();
// Fields
jgen.writeNumberField("id", bean.getId());
(...)
// Link
String href = (...)
HypermediaLink linkToSelf = new HypermediaLink();
linkToSelf.setHref(href + bean.getId());
linkToSelf.setRel("self");
jgen.writeObjectField("hypermediaLink", linkToSelf);
jgen.writeEndObject();
}
}
Here is the way to configure this within Restlet:
JacksonConverter jacksonConverter = getRegisteredJacksonConverter();
if (jacksonConverter != null) {
ObjectMapper objectMapper = jacksonConverter.getObjectMapper();
SimpleModule module = new SimpleModule("MyModule", new Version(1, 0, 0, null));
module.addSerializer(SomeBean.class, new SomeBeanSerializer());
objectMapper.registerModule(module);
}
This link could help you to see how to configure the Jackson converter of Restlet: https://templth.wordpress.com/2015/02/23/optimizing-restlet-server-applications/. It provides the content of the method getRegisteredJacksonConverter.
Edited: with version 2.3 of Restlet, something changes at this level. The object mapper is now brought by the JacksonRepresentation instead of the JacksonConverter itself. The object mapper is now instantiated for each representation of this kind. This means that you need to sub class these two elements to configure the custom serializer.
Here is the code of the class CustomJacksonRepresentation:
public class CustomJacksonRepresentation<T>
extends JacksonRepresentation<T> {
#Override
public ObjectMapper getObjectMapper() {
if (this.objectMapper == null) {
this.objectMapper = createObjectMapper();
SimpleModule module = new SimpleModule("MyModule",
new Version(1, 0, 0, null));
module.addSerializer(SomeBean.class,
new SomeBeanSerializer());
objectMapper.registerModule(module);
}
return this.objectMapper;
}
}
Here is the code of the class CustomJacksonConverter:
public class CustomJacksonConverter
extends JacksonConverter {
protected <T> JacksonRepresentation<T> create(
MediaType mediaType, T source) {
return new CustomJacksonRepresentation<T>(
mediaType, source);
}
protected <T> JacksonRepresentation<T> create(
Representation source, Class<T> objectClass) {
return new CustomJacksonRepresentation<T>(
source, objectClass);
}
}
This implemented, you need to replace the existing jackson converter that is automatically registered by Restlet. Here is the code to do that:
// Looking for the registered jackson converter
JacksonConverter jacksonConverter = null;
List<ConverterHelper> converters
= Engine.getInstance().getRegisteredConverters();
for (ConverterHelper converterHelper : converters) {
if (converterHelper instanceof JacksonConverter) {
jacksonConverter = (JacksonConverter) converterHelper;
break;
}
}
// converters
Engine.getInstance().getRegisteredConverters().remove(
jacksonConverter);
CustomJacksonConverter customJacksonConverter
= new CustomJacksonConverter();
Engine.getInstance().getRegisteredConverters().add(
customJacksonConverter);
You can notice that the way to manage converters will be refactored in the version 3 of Restlet to make things more convenient to configure! ;-)
Hope it helps you,
Thierry

Jackson - custom serializer that overrides only specific fields

I know how to use a custom serializer in Jackson (by extending JsonSerializer), but I want the default serializer to work for all fields, except for just 1 field, which I want to override using the custom serializer.
Annotations are not an option, because I am serializing a generated class (from Thrift).
How do I specify only certain fields to be overridden when writing a custom jackson serializer?
Update:
Here's the class I want to serialize:
class Student {
int age;
String firstName;
String lastName;
double average;
int numSubjects
// .. more such properties ...
}
The above class has many properies, most of which use native types. I want to just override a few properties in the custom serializer and let Jackson deal with the rest as usual. For e.g. I just want to convert the "age" field to a custom output.

Assuming your Target class is
public class Student {
int age;
String firstName;
String lastName;
double average;
int numSubjects;
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public double getAverage() {
return average;
}
public void setAverage(double average) {
this.average = average;
}
public int getNumSubjects() {
return numSubjects;
}
public void setNumSubjects(int numSubjects) {
this.numSubjects = numSubjects;
}
}
You need to write a custom serializer as given below
public class MyCustomSerializer extends JsonSerializer<Student> {
#Override
public void serialize(Student value, JsonGenerator jgen,
SerializerProvider provider) throws IOException,
JsonProcessingException {
if (value != null) {
jgen.writeStartObject();
jgen.writeStringField("age", "Age: " + value.getAge()); //Here a custom way to render age field is used
jgen.writeStringField("firstName", value.getFirstName());
jgen.writeStringField("lastName", value.getLastName());
jgen.writeNumberField("average", value.getAverage());
jgen.writeNumberField("numSubjects", value.getNumSubjects());
//Write other properties
jgen.writeEndObject();
}
}
}
then add it to the ObjectMapper
ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule("custom",
Version.unknownVersion());
module.addSerializer(Student.class, new MyCustomSerializer());
mapper.registerModule(module);
then use it like
Student s = new Student();
s.setAge(2);
s.setAverage(3.4);
s.setFirstName("first");
s.setLastName("last");
s.setNumSubjects(3);
StringWriter sw = new StringWriter();
mapper.writeValue(sw, s);
System.out.println(sw.toString());
It will produce a o/p like
{"age":"Age:
2","firstName":"first","lastName":"last","average":3.4,"numSubjects":3}

Just because you can not modify classes DOES NOT mean you could not use annotations: just use mix-in annotations. See this blog entry for example (or google for more with "jackson mixin annotations") for how to use this.
I have specifically used Jackson with protobuf- and thrift-generated classes, and they work pretty well. For earlier Thrift versions, I had to disable discovery of "is-setters", methods Thrift generates to see if a specific property has been explicitly set, but otherwise things worked fine.

I faced the same issue, and I solved it with CustomSerializerFactory.
This approach allows you to ignore some specific field for either for all objects, or for specific types.
public class EntityCustomSerializationFactory extends CustomSerializerFactory {
//ignored fields
private static final Set<String> IGNORED_FIELDS = new HashSet<String>(
Arrays.asList(
"class",
"value",
"some"
)
);
public EntityCustomSerializationFactory() {
super();
}
public EntityCustomSerializationFactory(Config config) {
super(config);
}
#Override
protected void processViews(SerializationConfig config, BeanSerializerBuilder builder) {
super.processViews(config, builder);
//ignore fields only for concrete class
//note, that you can avoid or change this check
if (builder.getBeanDescription().getBeanClass().equals(Entity.class)){
//get original writer
List<BeanPropertyWriter> originalWriters = builder.getProperties();
//create actual writers
List<BeanPropertyWriter> writers = new ArrayList<BeanPropertyWriter>();
for (BeanPropertyWriter writer: originalWriters){
String propName = writer.getName();
//if it isn't ignored field, add to actual writers list
if (!IGNORED_FIELDS.contains(propName)){
writers.add(writer);
}
}
builder.setProperties(writers);
}
}
}
And afterwards you can use it something like the following:
objectMapper.setSerializerFactory(new EntityCustomSerializationFactory());
objectMapper.writeValueAsString(new Entity());//response will be without ignored fields

In case you don't want to pollute your model with annotations, you could use mixins.
ObjectMapper mapper = new ObjectMapper();
SimpleModule simpleModule = new SimpleModule();
simpleModule.setMixInAnnotation(Student.class, StudentMixin.class);
mapper.registerModule(simpleModule);
And you want to override id field for example:
public abstract class StudentMixin {
#JsonSerialize(using = StudentIdSerializer.class)
public String id;
}
Do whatever you need with the field:
public class StudentIdSerializer extends JsonSerializer<Integer> {
#Override
public void serialize(Integer integer, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
jsonGenerator.writeString(String.valueOf(integer * 2));
}
}

with the help of #JsonView we can decide fields of model classes to serialize which satisfy the minimal criteria ( we have to define the criteria) like we can have one core class with 10 properties but only 5 properties can be serialize which are needful for client only
Define our Views by simply creating following class:
public class Views
{
static class Android{};
static class IOS{};
static class Web{};
}
Annotated model class with views:
public class Demo
{
public Demo()
{
}
#JsonView(Views.IOS.class)
private String iosField;
#JsonView(Views.Android.class)
private String androidField;
#JsonView(Views.Web.class)
private String webField;
// getters/setters
...
..
}
Now we have to write custom json converter by simply extending HttpMessageConverter class from spring as:
public class CustomJacksonConverter implements HttpMessageConverter<Object>
{
public CustomJacksonConverter()
{
super();
//this.delegate.getObjectMapper().setConfig(this.delegate.getObjectMapper().getSerializationConfig().withView(Views.ClientView.class));
this.delegate.getObjectMapper().configure(MapperFeature.DEFAULT_VIEW_INCLUSION, true);
this.delegate.getObjectMapper().setSerializationInclusion(Include.NON_NULL);
}
// a real message converter that will respond to methods and do the actual work
private MappingJackson2HttpMessageConverter delegate = new MappingJackson2HttpMessageConverter();
#Override
public boolean canRead(Class<?> clazz, MediaType mediaType) {
return delegate.canRead(clazz, mediaType);
}
#Override
public boolean canWrite(Class<?> clazz, MediaType mediaType) {
return delegate.canWrite(clazz, mediaType);
}
#Override
public List<MediaType> getSupportedMediaTypes() {
return delegate.getSupportedMediaTypes();
}
#Override
public Object read(Class<? extends Object> clazz,
HttpInputMessage inputMessage) throws IOException,
HttpMessageNotReadableException {
return delegate.read(clazz, inputMessage);
}
#Override
public void write(Object obj, MediaType contentType, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException
{
synchronized(this)
{
String userAgent = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest().getHeader("userAgent");
if ( userAgent != null )
{
switch (userAgent)
{
case "IOS" :
this.delegate.getObjectMapper().setConfig(this.delegate.getObjectMapper().getSerializationConfig().withView(Views.IOS.class));
break;
case "Android" :
this.delegate.getObjectMapper().setConfig(this.delegate.getObjectMapper().getSerializationConfig().withView(Views.Android.class));
break;
case "Web" :
this.delegate.getObjectMapper().setConfig(this.delegate.getObjectMapper().getSerializationConfig().withView( Views.Web.class));
break;
default:
this.delegate.getObjectMapper().setConfig(this.delegate.getObjectMapper().getSerializationConfig().withView( null ));
break;
}
}
else
{
// reset to default view
this.delegate.getObjectMapper().setConfig(this.delegate.getObjectMapper().getSerializationConfig().withView( null ));
}
delegate.write(obj, contentType, outputMessage);
}
}
}
Now there is need to tell spring to use this custom json convert by simply putting this in dispatcher-servlet.xml
<mvc:annotation-driven>
<mvc:message-converters register-defaults="true">
<bean id="jsonConverter" class="com.mactores.org.CustomJacksonConverter" >
</bean>
</mvc:message-converters>
</mvc:annotation-driven>
That's how you will able to decide which fields to get serialize.
Thanx