public class RESTDataServiceClient{
private Client client;
private String dataServiceUri;
private String dataServiceResource;
private CustomData customData;
public RESTDataServiceClient(String dataServiceUri, String dataServiceResource, Client client){
this.client = client;
this.dataServiceUri = dataServiceUri;
this.dataServiceResource = dataServiceResource;
}
#Override
public CustomData getCustomData() {
WebTarget dataServiceTarget = client.target(dataServiceUri).path(dataServiceResource);
Invocation.Builder invocationBuilder = dataServiceTarget.request(MediaType.APPLICATION_JSON_TYPE);
Response response = invocationBuilder.get();
myCustomData = response.readEntity(CustomData.class);
return myCustomData;
}
}
CustomData.java
public class CustomData{
private TLongObjectMap<Map<String, TIntIntMap>> data;
public CustomData() {
this.data = new TLongObjectHashMap<>();
}
//getter and setter
}
sample json content
{"50000":{"testString":{"1":10}},"50001":{"testString1":{"2":11}} }
I am trying to get data from a data service which is going to return data in a JSON format. I am trying to write a client to read that JSON into a custom object. The CustomData contains a nested trove map datastructure. we wrote a custom serializer for that and the server part works fine. I am unable to get the rest client read the data into an object, but reading into string works. I tried above pasted code with the sample data and i get the error below.
javax.ws.rs.ProcessingException: Error reading entity from input stream.
at org.glassfish.jersey.message.internal.InboundMessageContext.readEntity(InboundMessageContext.java:866)
at org.glassfish.jersey.message.internal.InboundMessageContext.readEntity(InboundMessageContext.java:783)
at org.glassfish.jersey.client.ClientResponse.readEntity(ClientResponse.java:326)
at org.glassfish.jersey.client.InboundJaxrsResponse$1.call(InboundJaxrsResponse.java:111)
at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
at org.glassfish.jersey.internal.Errors.process(Errors.java:228)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:399)
at org.glassfish.jersey.client.InboundJaxrsResponse.readEntity(InboundJaxrsResponse.java:108)
at com.sample.data.RESTDataServiceClient.getCustomData(RESTDataServiceClient.java:42)
Caused by: com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "50000" (class com.sample.data.CustomData), not marked as ignorable (0 known properties: ])
at [Source: org.glassfish.jersey.message.internal.ReaderInterceptorExecutor$UnCloseableInputStream#2cb89281; line: 1, column: 14] (through reference chain: com.sample.data.CustomData["50000"])
at com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException.from(UnrecognizedPropertyException.java:51)
at com.fasterxml.jackson.databind.DeserializationContext.reportUnknownProperty(DeserializationContext.java:671)
at com.fasterxml.jackson.databind.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:773)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownProperty(BeanDeserializerBase.java:1297)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownVanilla(BeanDeserializerBase.java:1275)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:247)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:118)
at com.fasterxml.jackson.databind.ObjectReader._bind(ObjectReader.java:1233)
at com.fasterxml.jackson.databind.ObjectReader.readValue(ObjectReader.java:677)
at com.fasterxml.jackson.jaxrs.base.ProviderBase.readFrom(ProviderBase.java:777)
at org.glassfish.jersey.message.internal.ReaderInterceptorExecutor$TerminalReaderInterceptor.invokeReadFrom(ReaderInterceptorExecutor.java:264)
at org.glassfish.jersey.message.internal.ReaderInterceptorExecutor$TerminalReaderInterceptor.aroundReadFrom(ReaderInterceptorExecutor.java:234)
at org.glassfish.jersey.message.internal.ReaderInterceptorExecutor.proceed(ReaderInterceptorExecutor.java:154)
at org.glassfish.jersey.message.internal.MessageBodyFactory.readFrom(MessageBodyFactory.java:1124)
at org.glassfish.jersey.message.internal.InboundMessageContext.readEntity(InboundMessageContext.java:851)
... 38 more
TLongObjectMap is not deserializable out of the box, so how you made a custom serializer you also need to implement a custom deserializer. You can package these up nicely in a module and add it to your ObjectMapper.
It looks like there is a Trove module in development right now, which you can download and add to your ObjectMapper the same as the example below. The TIntObjectMapDeserializer implementation in that link is much more robust then my solution, so I would recommend using that class in your project if possible.
If you want to try and write it yourself, here's a starting point that properly deserializes your provided example:
public class FakeTest {
#Test
public void test() throws Exception {
ObjectMapper om = new ObjectMapper();
om.registerModule(new CustomModule());
String s = "{\"50000\":{\"testString\":{\"1\":10}},\"50001\":{\"testString1\":{\"2\":11}} }";
CustomData cd = om.readValue(s, CustomData.class);
System.out.println(cd.getData());
}
public static class CustomData {
private TLongObjectMap<Map<String, TIntIntMap>> data;
public CustomData() {
this.data = new TLongObjectHashMap<>();
}
public TLongObjectMap<Map<String, TIntIntMap>> getData() { return data; }
public void setData(TLongObjectMap<Map<String, TIntIntMap>> data) { this.data = data; }
}
public static class CustomModule extends SimpleModule {
public CustomModule() {
addSerializer(CustomData.class, new CustomSerializer());
addDeserializer(CustomData.class, new CustomDeserializer());
}
public static class CustomSerializer extends JsonSerializer<CustomData> {
#Override
public void serialize(CustomData value, JsonGenerator jgen, SerializerProvider provider) throws IOException {
// add custom serializer here
}
}
public static class CustomDeserializer extends JsonDeserializer<CustomData> {
#Override
public CustomData deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
TLongObjectMap<Map<String, TIntIntMap>> data = new TLongObjectHashMap<>();
ObjectNode node = jsonParser.getCodec().readTree(jsonParser);
Iterator<Map.Entry<String,JsonNode>> fields = node.fields();
while (fields.hasNext()) {
Map.Entry<String, JsonNode> entry = fields.next();
ObjectNode value = (ObjectNode) entry.getValue();
Map.Entry<String, JsonNode> innerField = value.fields().next();
ObjectNode innerNode = (ObjectNode) innerField.getValue();
Map.Entry<String, JsonNode> innerInnerField = innerNode.fields().next();
TIntIntMap intMap = new TIntIntHashMap();
intMap.put(Integer.parseInt(innerInnerField.getKey()), innerInnerField.getValue().asInt());
Map<String, TIntIntMap> innerMap = Collections.singletonMap(innerField.getKey(), intMap);
data.put(Long.parseLong(entry.getKey()), innerMap);
}
CustomData customData = new CustomData();
customData.setData(data);
return customData;
}
}
}
}
Related
I have an entity with multiple #ManyToOne associations. I am using spring-boot to expose a REST API. Currently, I have multiple REST API's which return a JSON response of the whole entity, including associations.
But I don't want to serialize all associated objects in all REST APIs.
For example
API-1 should return parent + associationA object
API-2 should return parent + associationA + associationB object
API-3 should return parent + associationB + associationC + associationD
So, in my serialization process, I want to ignore all association except associationA for API-1.
For API-2 I want to ignore other associations except A and B
How do I dynamically ignore these properties during Jackson serialization?
Notes:
I'm using the same class for each; I am not interested in creating a DTO for each API.
Any suggestions are kingly appreciated.
I've put together three approaches for performing dynamic filtering in Jackson. One of them must suit your needs.
Using #JsonView
You could use #JsonView:
public class Views {
interface Simple { }
interface Detailed extends Simple { }
}
public class Foo {
#JsonView(Views.Simple.class)
private String name;
#JsonView(Views.Detailed.class)
private String details;
// Getters and setters
}
#RequestMapping("/foo")
#JsonView(Views.Detailed.class)
public Foo getFoo() {
Foo foo = new Foo();
return foo;
}
Alternatively you can set the view dynamically with MappingJacksonValue.
#RequestMapping("/foo")
public MappingJacksonValue getFoo() {
Foo foo = new Foo();
MappingJacksonValue result = new MappingJacksonValue(foo);
result.setSerializationView(Views.Detailed.class);
return result;
}
Using a BeanSerializerModifier
You could extend BeanSerializerModifier and then override the changeProperties() method. It allows you to add, remove or replace any of properties for serialization, according to your needs:
public class CustomSerializerModifier extends BeanSerializerModifier {
#Override
public List<BeanPropertyWriter> changeProperties(SerializationConfig config,
BeanDescription beanDesc, List<BeanPropertyWriter> beanProperties) {
// In this method you can add, remove or replace any of passed properties
return beanProperties;
}
}
Then register the serializer as a module in your ObjectMapper:
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new SimpleModule() {
#Override
public void setupModule(SetupContext context) {
super.setupModule(context);
context.addBeanSerializerModifier(new CustomSerializerModifier());
}
});
Check examples here and here.
Using #JsonFilter with a SimpleBeanPropertyFilter
Another approach involves #JsonFilter:
#JsonFilter("customPropertyFilter")
public class Foo {
private String name;
private String details;
// Getters and setters
}
Extend SimpleBeanPropertyFilter and override the serializeAsField() method according to your needs:
public class CustomPropertyFilter extends SimpleBeanPropertyFilter {
#Override
public void serializeAsField(Object pojo, JsonGenerator jgen,
SerializerProvider provider,
PropertyWriter writer) throws Exception {
// Serialize a field
// writer.serializeAsField(pojo, jgen, provider, writer);
// Omit a field from serialization
// writer.serializeAsOmittedField(pojo, jgen, provider);
}
}
Then register the filter in your ObjectMapper:
FilterProvider filterProvider = new SimpleFilterProvider()
.addFilter("customPropertyFilter", new CustomPropertyFilter());
ObjectMapper mapper = new ObjectMapper();
mapper.setFilterProvider(filterProvider);
If you want to make your filter "global", that is, to be applied to all beans, you can create a mix-in class and annotate it with #JsonFilter("customPropertyFilter"):
#JsonFilter("customPropertyFilter")
public class CustomPropertyFilterMixIn {
}
Then bind the mix-in class to Object:
mapper.addMixIn(Object.class, CustomPropertyFilterMixIn.class);
public static <T> String getNonNullFieldsSerialized(T object, ObjectMapper objectMapper)throws JsonProcessingException {
Map<String, Object> objectMap = objectMapper.convertValue(object, new TypeReference<Map<String, Object>>() {});
Map<String, Object> objectMapNonNullValues = objectMap.entrySet().stream()
.filter(stringObjectEntry -> Objects.nonNull(stringObjectEntry.getValue()))
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
return objectMapper.writeValueAsString(objectMapNonNullValues);
}
This will basically ignore all the fields that are non-null. Similarly you can ignore other fields by changing the map filter condition.
I have implemented dynamic filter on data getting from db and returning it using rest api.I have avoided using MappingJacksonValue.As it was getting issue while object chaining
#GetMapping("/courses")
public ResponseEntity<JpaResponse> allCourse() throws Exception {
JpaResponse response = null;
ObjectMapper mapper = new ObjectMapper();
mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
List<Course> course = service.findAllCourse();
SimpleBeanPropertyFilter filter = SimpleBeanPropertyFilter.filterOutAllExcept("name","reviews");
FilterProvider filterProvider = new SimpleFilterProvider().addFilter("jpafilter", filter).setFailOnUnknownId(false);
ObjectWriter writer = mapper.writer(filterProvider);
String writeValueAsString = writer.writeValueAsString(course);
List<Course> resultcourse = mapper.readValue(writeValueAsString,List.class);
response = new JpaResponse(HttpStatus.OK.name(),resultcourse);
return new ResponseEntity<>(response, HttpStatus.OK);
}
public class JpaResponse {
private String status;
private Object data;
public JpaResponse() {
super();
}
public JpaResponse(String status, Object data) {
super();
this.status = status;
this.data = data;
}
}
I'm trying to obtain POJO instances using Gson and Retrofit2.
A typical JSON response looks like this.
My issue is with the Infobox field. In some cases, (like this) the field would be an object of the following type and an empty string otherwise.
class Infobox {
public List<Content> content = new ArrayList<>();
public List<Metum> meta;
}
class Content {
public String dataType;
public String value;
public String label;
public Integer wikiOrder;
}
class Metum {
public String dataType;
public String value;
public String label;
}
I tried writing a TypeAdapter as below
class InfoboxAdapter extends TypeAdapter<Infobox> {
final Gson embedded = new Gson();
#Override
public void write(JsonWriter out, Infobox infobox) throws IOException {
if (infobox == null) {
out.nullValue();
return;
}
out.beginObject();
out.name("content");
embedded.toJson(embedded.toJsonTree(infobox.content), out);
out.name("meta");
embedded.toJson(embedded.toJsonTree(infobox.meta), out);
out.endObject();
}
#Override
public Infobox read(JsonReader in) throws IOException {
if ("".equals(in.peek())) {
return null;
}
return embedded.fromJson(in, Infobox.class);
}
But it fails with java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING
The more confusing fact is that the field meta in the response, which is also an object, will in some cases have the value as null (and not an empty string like infobox)
I'd prefer to be able to do it using Gson as I've used it for everything else and I don't want to add another dependency
Hi Please go to :http://www.jsonschema2pojo.org/
paste your code. this sites automatically create your all related classes.
if issue please have a look at this link.
my drive link
I ended up using a JsonDeserializer. Google recommends:
New applications should prefer TypeAdapter, whose streaming API is more efficient than this interface's tree API.
But I didn't notice any performance impact for my use. I might someday rewrite this to use a TypeAdapter, but this works for me in till then
class InfoboxDeserialiser implements JsonDeserializer<Infobox> {
#Override
public Infobox deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
try {
if (json.isJsonNull() || json.isJsonPrimitive()) {
return null;
}
JsonObject jsonObject = json.getAsJsonObject();
Infobox infobox = new Infobox();
JsonArray jsonContent = jsonObject.get("content").getAsJsonArray();
JsonArray jsonMeta = jsonObject.get("meta").getAsJsonArray();
infobox.content = new Content[jsonContent.size()];
for (int i = 0; i < jsonContent.size(); i++) {
infobox.content[i] = context.deserialize(jsonContent.get(i), Content.class);
}
infobox.meta = new Metum[jsonMeta.size()];
for (int i = 0; i < jsonMeta.size(); i++) {
infobox.meta[i] = context.deserialize(jsonContent.get(i), Metum.class);
}
return infobox;
} catch (Exception e) {
Timber.e(e, "Failed to deserialise the infobox");
return null;
}
}
}
Where the classes are as follows
class Metum {
public String dataType;
public String value;
public String label;
}
class Content {
public String dataType;
public String value;
public String label;
public Integer wikiOrder;
}
I register this deserializer while creating the service object
GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.registerTypeAdapter(Infobox.class, new InfoboxDeserialiser());
GsonConverterFactory converterFactory = GsonConverterFactory.create(gsonBuilder.create());
Retrofit.Builder builder = new Retrofit.Builder()
.baseUrl("https://api.duckduckgo.com/")
.addConverterFactory(converterFactory);
I am writing a rest service using spring MVC which produces JSON response. It should allow client to select only the given fields in response, means client can mention the fields he is interested in as url parameter like ?fields=field1,field2.
Using Jackson annotations does not provide what I am looking for as it is not dynamic also the filters in Jackson doesnt seem to be promising enough.
So far I am thinking to implement a custom message converter which can take care of this.
Is there any other better way to achieve this? I would like if this logic is not coupled with my services or controllers.
From Spring 4.2, #JsonFilter is supported in MappingJacksonValue
Issue : SPR-12586 : Support Jackson #JsonFilter
Commit : ca06582
You can directly inject PropertyFilter to MappingJacksonValue in a controller.
#RestController
public class BookController {
private static final String INCLUSION_FILTER = "inclusion";
#RequestMapping("/novels")
public MappingJacksonValue novel(String[] include) {
#JsonFilter(INCLUSION_FILTER)
class Novel extends Book {}
Novel novel = new Novel();
novel.setId(3);
novel.setTitle("Last summer");
novel.setAuthor("M.K");
MappingJacksonValue res = new MappingJacksonValue(novel);
PropertyFilter filter = SimpleBeanPropertyFilter.filterOutAllExcept(include);
FilterProvider provider = new SimpleFilterProvider().addFilter(INCLUSION_FILTER, filter);
res.setFilters(provider);
return res;
}
or you can declare global policy by ResponseBodyAdvice. The following example implements filtering policy by "exclude" parameter.
#ControllerAdvice
public class DynamicJsonResponseAdvice extends AbstractMappingJacksonResponseBodyAdvice {
public static final String EXCLUDE_FILTER_ID = "dynamicExclude";
private static final String WEB_PARAM_NAME = "exclude";
private static final String DELI = ",";
private static final String[] EMPTY = new String[]{};
#Override
protected void beforeBodyWriteInternal(MappingJacksonValue container, MediaType contentType,
MethodParameter returnType, ServerHttpRequest req, ServerHttpResponse res) {
if (container.getFilters() != null ) {
// It will be better to merge FilterProvider
// If 'SimpleFilterProvider.addAll(FilterProvider)' is provided in Jackson, it will be easier.
// But it isn't supported yet.
return;
}
HttpServletRequest baseReq = ((ServletServerHttpRequest) req).getServletRequest();
String exclusion = baseReq.getParameter(WEB_PARAM_NAME);
String[] attrs = StringUtils.split(exclusion, DELI);
container.setFilters(configFilters(attrs));
}
private FilterProvider configFilters(String[] attrs) {
String[] ignored = (attrs == null) ? EMPTY : attrs;
PropertyFilter filter = SimpleBeanPropertyFilter.serializeAllExcept(ignored);
return new SimpleFilterProvider().addFilter(EXCLUDE_FILTER_ID, filter);
}
}
IMHO, the simplest way to do that would be to use introspection to dynamically generate a hash containing selected fields and then serialize that hash using Json. You simply have to decide what is the list of usable fields (see below).
Here are two example functions able to do that, first gets all public fields and public getters, the second gets all declared fields (including private ones) in current class and all its parent classes :
public Map<String, Object> getPublicMap(Object obj, List<String> names)
throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {
List<String> gettedFields = new ArrayList<String>();
Map<String, Object> values = new HashMap<String, Object>();
for (Method getter: obj.getClass().getMethods()) {
if (getter.getName().startsWith("get") && (getter.getName().length > 3)) {
String name0 = getter.getName().substring(3);
String name = name0.substring(0, 1).toLowerCase().concat(name0.substring(1));
gettedFields.add(name);
if ((names == null) || names.isEmpty() || names.contains(name)) {
values.put(name, getter.invoke(obj));
}
}
}
for (Field field: obj.getClass().getFields()) {
String name = field.getName();
if ((! gettedFields.contains(name)) && ((names == null) || names.isEmpty() || names.contains(name))) {
values.put(name, field.get(obj));
}
}
return values;
}
public Map<String, Object> getFieldMap(Object obj, List<String> names)
throws IllegalArgumentException, IllegalAccessException {
Map<String, Object> values = new HashMap<String, Object>();
for (Class<?> clazz = obj.getClass(); clazz != Object.class; clazz = clazz.getSuperclass()) {
for (Field field : clazz.getDeclaredFields()) {
String name = field.getName();
if ((names == null) || names.isEmpty() || names.contains(name)) {
field.setAccessible(true);
values.put(name, field.get(obj));
}
}
}
return values;
}
Then you only have to get the result of one of this function (or of one you could adapt to your requirements) and serialize it with Jackson.
If you have custom encoding of you domain objects, you would have to maintain the serialization rules in two different places : hash generation and Jackson serialization. In that case, you could simply generate the full class serialization with Jackson and filter the generated string afterwards. Here is an example of such a filter function :
public String jsonSub(String json, List<String> names) throws IOException {
if ((names == null) || names.isEmpty()) {
return json;
}
ObjectMapper mapper = new ObjectMapper();
Map<String, Object> map = mapper.readValue(json, HashMap.class);
for (String name: map.keySet()) {
if (! names.contains(name)) {
map.remove(name);
}
}
return mapper.writeValueAsString(map);
}
Edit : integration in Spring MVC
As you are speaking of a web service and of Jackson, I assume that you use Spring RestController or ResponseBody annotations and (under the hood) a MappingJackson2HttpMessageConverter. If you use Jackson 1 instead, it should be a MappingJacksonHttpMessageConverter.
What I propose is simply to add a new HttpMessageConverter that could make use of one of the above filtering functions, and delegate actual work (and also ancilliary methods) to a true MappingJackson2HttpMessageConverter. In the write method of that new converter, it is possible to have access to the eventual fields request parameter with no need for an explicit ThreadLocal variable thanks to Spring RequestContextHolder. That way :
you keep a clear separation of roles with no modification on existing controllers
you have no modification in Jackson2 configuration
you need no new ThreadLocal variable and simply use a Spring class in a class already tied to Spring since it implements HttpMessageConverter
Here is an example of such a message converter :
public class JsonConverter implements HttpMessageConverter<Object> {
private static final Logger logger = LoggerFactory.getLogger(JsonConverter.class);
// a real message converter that will respond to ancilliary methods and do the actual work
private HttpMessageConverter<Object> delegate =
new MappingJackson2HttpMessageConverter();
// allow configuration of the fields name
private String fieldsParam = "fields";
public void setFieldsParam(String fieldsParam) {
this.fieldsParam = fieldsParam;
}
#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 t, MediaType contentType, HttpOutputMessage outputMessage)
throws IOException, HttpMessageNotWritableException {
// is there a fields parameter in request
String[] fields = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes())
.getRequest().getParameterValues(fieldsParam);
if (fields != null && fields.length != 0) {
// get required field names
List<String> names = new ArrayList<String>();
for (String field : fields) {
String[] f_names = field.split("\\s*,\\s*");
names.addAll(Arrays.asList(f_names));
}
// special management for Map ...
if (t instanceof Map) {
Map<?, ?> tmap = (Map<?, ?>) t;
Map<String, Object> map = new LinkedHashMap<String, Object>();
for (Entry entry : tmap.entrySet()) {
String name = entry.getKey().toString();
if (names.contains(name)) {
map.put(name, entry.getValue());
}
}
t = map;
} else {
try {
Map<String, Object> map = getMap(t, names);
t = map;
} catch (Exception ex) {
throw new HttpMessageNotWritableException("Error in field extraction", ex);
}
}
}
delegate.write(t, contentType, outputMessage);
}
/**
* Create a Map by keeping only some fields of an object
* #param obj the Object
* #param names names of the fields to keep in result Map
* #return a map containing only requires fields and their value
* #throws IllegalArgumentException
* #throws IllegalAccessException
*/
public static Map<String, Object> getMap(Object obj, List<String> names)
throws IllegalArgumentException, IllegalAccessException {
Map<String, Object> values = new HashMap<String, Object>();
for (Class<?> clazz = obj.getClass(); clazz != Object.class; clazz = clazz.getSuperclass()) {
for (Field field : clazz.getDeclaredFields()) {
String name = field.getName();
if (names.contains(name)) {
field.setAccessible(true);
values.put(name, field.get(obj));
}
}
}
return values;
}
}
If you want the converter to be more versatile, you could define an interface
public interface FieldsFilter {
Map<String, Object> getMap(Object obj, List<String> names)
throws IllegalAccessException, IllegalArgumentException, InvocationTargetException;
}
and inject it with an implementation of that.
Now you must ask Spring MVC to use that custom message controller.
If you use XML config, you simply declare it in the <mvc:annotation-driven> element :
<mvc:annotation-driven >
<mvc:message-converters>
<bean id="jsonConverter" class="org.example.JsonConverter"/>
</mvc:message-converters>
</mvc:annotation-driven>
And if you use Java configuration, it is almost as simple :
#EnableWebMvc
#Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
#Autowired JsonConverter jsonConv;
#Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
converters.add(jsonConv);
StringHttpMessageConverter stringConverter = new StringHttpMessageConverter();
stringConverter.setWriteAcceptCharset(false);
converters.add(new ByteArrayHttpMessageConverter());
converters.add(stringConverter);
converters.add(new ResourceHttpMessageConverter());
converters.add(new SourceHttpMessageConverter<Source>());
converters.add(new AllEncompassingFormHttpMessageConverter());
converters.add(new MappingJackson2HttpMessageConverter());
}
}
but here you have to explicitely add all the default message converters that you need.
I've never done this but after looking at this page http://wiki.fasterxml.com/JacksonFeatureJsonFilter it seems that it would be possible to do what you want this way:
1) Create a custom JacksonAnnotationIntrospector implementation (by extending default one) that will use a ThreadLocal variable to choose a filter for current request and also create a custom FilterProvider that would provide that filter.
2) Configure the message converter's ObjectMapper to use the custom introspector and filter provider
3) Create an MVC interceptor for REST service that detects fields request parameter and configures a new filter for current request via your custom filter provider (this should be a thread local filter). ObjectMapper should pick it up through your custom JacksonAnnotationIntrospector.
I'm not 100% certain that this solution would be thread safe (it depends on how ObjectMapper uses annotation introspector and filter provider internally).
- EDIT -
Ok I did a test implementation and found out that step 1) wouldn't work because Jackson caches the result of AnnotationInterceptor per class. I modified idea to apply dynamic filtering only on annotated controller methods and only if the object doesn't have anoter JsonFilter already defined.
Here's the solution (it's quite lengthy):
DynamicRequestJsonFilterSupport class manages the per-request fields to be filtered out:
public class DynamicRequestJsonFilterSupport {
public static final String DYNAMIC_FILTER_ID = "___DYNAMIC_FILTER";
private ThreadLocal<Set<String>> filterFields;
private DynamicIntrospector dynamicIntrospector;
private DynamicFilterProvider dynamicFilterProvider;
public DynamicRequestJsonFilterSupport() {
filterFields = new ThreadLocal<Set<String>>();
dynamicFilterProvider = new DynamicFilterProvider(filterFields);
dynamicIntrospector = new DynamicIntrospector();
}
public FilterProvider getFilterProvider() {
return dynamicFilterProvider;
}
public AnnotationIntrospector getAnnotationIntrospector() {
return dynamicIntrospector;
}
public void setFilterFields(Set<String> fieldsToFilter) {
filterFields.set(Collections.unmodifiableSet(new HashSet<String>(fieldsToFilter)));
}
public void setFilterFields(String... fieldsToFilter) {
filterFields.set(Collections.unmodifiableSet(new HashSet<String>(Arrays.asList(fieldsToFilter))));
}
public void clear() {
filterFields.remove();
}
public static class DynamicIntrospector extends JacksonAnnotationIntrospector {
#Override
public Object findFilterId(Annotated annotated) {
Object result = super.findFilterId(annotated);
if (result != null) {
return result;
} else {
return DYNAMIC_FILTER_ID;
}
}
}
public static class DynamicFilterProvider extends FilterProvider {
private ThreadLocal<Set<String>> filterFields;
public DynamicFilterProvider(ThreadLocal<Set<String>> filterFields) {
this.filterFields = filterFields;
}
#Override
public BeanPropertyFilter findFilter(Object filterId) {
return null;
}
#Override
public PropertyFilter findPropertyFilter(Object filterId, Object valueToFilter) {
if (filterId.equals(DYNAMIC_FILTER_ID) && filterFields.get() != null) {
return SimpleBeanPropertyFilter.filterOutAllExcept(filterFields.get());
}
return super.findPropertyFilter(filterId, valueToFilter);
}
}
}
JsonFilterInterceptor intercepts controller methods annotated with custom #ResponseFilter annotation.
public class JsonFilterInterceptor implements HandlerInterceptor {
#Autowired
private DynamicRequestJsonFilterSupport filterSupport;
private ThreadLocal<Boolean> requiresReset = new ThreadLocal<Boolean>();
#Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
if (handler instanceof HandlerMethod) {
HandlerMethod method = (HandlerMethod) handler;
ResponseFilter filter = method.getMethodAnnotation(ResponseFilter.class);
String[] value = filter.value();
String param = filter.param();
if (value != null && value.length > 0) {
filterSupport.setFilterFields(value);
requiresReset.set(true);
} else if (param != null && param.length() > 0) {
String filterParamValue = request.getParameter(param);
if (filterParamValue != null) {
filterSupport.setFilterFields(filterParamValue.split(","));
}
}
}
requiresReset.remove();
return true;
}
#Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
}
#Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
Boolean reset = requiresReset.get();
if (reset != null && reset) {
filterSupport.clear();
}
}
}
Here's the custom #ResponseFilter annotation. You can either define a static filter (via annotation's value property) or a filter based on request param (via annotation's param property):
#Target({ElementType.METHOD, ElementType.TYPE})
#Retention(RetentionPolicy.RUNTIME)
#Documented
public #interface ResponseFilter {
String[] value() default {};
String param() default "";
}
You will need to setup the message converter and the interceptor in the config class:
...
#Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
converters.add(converter());
}
#Bean
JsonFilterInterceptor jsonFilterInterceptor() {
return new JsonFilterInterceptor();
}
#Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(jsonFilterInterceptor);
}
#Bean
DynamicRequestJsonFilterSupport filterSupport() {
return new DynamicRequestJsonFilterSupport();
}
#Bean
MappingJackson2HttpMessageConverter converter() {
MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
ObjectMapper mapper = new ObjectMapper();
mapper.setAnnotationIntrospector(filterSupport.getAnnotationIntrospector());
mapper.setFilters(filterSupport.getFilterProvider());
converter.setObjectMapper(mapper);
return converter;
}
...
And finally, you can use the filter like this:
#RequestMapping("/{id}")
#ResponseFilter(param = "fields")
public Invoice getInvoice(#PathVariable("id") Long id) { ... }
When request is made to /invoices/1?fields=id,number response will be
filtered and only id and number properties will be returned.
Please note I haven't tested this thoroughly but it should get you started.
Would populating a HashMap from the object not suite the requirements? You could then just parse the HashMap. I have done something similar with GSON in the past where I had to provide a simple entity and ended up just populating a HashMap and then serializing it, it was far more maintainable than over engineering a whole new system.
Good day,
I am currently integration attempting to consume a REST service that produces JSON (written in .NET) using Jackson (with Jersey). The JSON consists of a possible error message and an array of objects. Below is a sample of the JSON returned as produced by Jersey's logging filter:
{
"error":null,
"object":"[{\"Id\":16,\"Class\":\"ReportType\",\"ClassID\":\"4\",\"ListItemParent_ID\":4,\"Item\":\"Pothole\",\"Description\":\"Pothole\",\"Sequence\":1,\"LastEditDate\":null,\"LastEditor\":null,\"ItemStatus\":\"Active\",\"ItemColor\":\"#00AF64\"}]"
}
I have two classes to represent the type (the outer ListResponse):
public class ListResponse {
public String error;
public ArrayList<ListItem> object;
public ListResponse() {
}
}
and (the inner ListItem):
public class ListItem {
#JsonProperty("Id")
public int id;
#JsonProperty("Class")
public String classType;
#JsonProperty("ClassID")
public String classId;
#JsonProperty("ListItemParent_ID")
public int parentId;
#JsonProperty("Item")
public String item;
#JsonProperty("Description")
public String description;
#JsonAnySetter
public void handleUnknown(String key, Object value) {}
public ListItem() {
}
}
The class that invokes and returns the JSON looks like this:
public class CitizenPlusService {
private Client client = null;
private WebResource service = null;
public CitizenPlusService() {
initializeService("http://localhost:59105/PlusService/");
}
private void initializeService(String baseURI) {
// Use the default client configuration.
ClientConfig clientConfig = new DefaultClientConfig();
clientConfig.getClasses().add(JacksonJsonProvider.class);
client = Client.create(clientConfig);
// Add a logging filter to track communication between server and client.
client.addFilter(new LoggingFilter());
// Add the base URI
service = client.resource(UriBuilder.fromUri(baseURI).build());
}
public ListResponse getListItems(String id) throws Exception
{
ListResponse response = service.path("GetListItems").path(id).accept(MediaType.APPLICATION_JSON_TYPE, MediaType.APPLICATION_XML_TYPE).get(ListResponse.class);
return response;
}
}
The important call here is the getListItems method. Running the code in a test harness, produces the following:
org.codehaus.jackson.map.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of VALUE_STRING token
at [Source: java.io.StringReader#49497eb8; line: 1, column: 14] (through reference chain: citizenplus.types.ListResponse["object"])
Please assist.
Regards,
Carl-Peter Meyer
You may be missing a #JsonDeserialize attribute as the type information does get lost in generics at run-time. Also you should avoid using concrete classes for collections if you can.
public class ListResponse {
public String error;
#JsonDeserialize(as=ArrayList.class, contentAs=ListItem.class)
public List<ListItem> object;
}
Your problem is that the 'object' property value is a String and not an array! The string contains a JSON array but Jackson expects a native array (without the wrapping quotes).
I had the same problem and I created a custom deserializer, which will deserialize a string value to a generic collection of the desired type:
public class JsonCollectionDeserializer extends StdDeserializer<Object> implements ContextualDeserializer {
private final BeanProperty property;
/**
* Default constructor needed by Jackson to be able to call 'createContextual'.
* Beware, that the object created here will cause a NPE when used for deserializing!
*/
public JsonCollectionDeserializer() {
super(Collection.class);
this.property = null;
}
/**
* Constructor for the actual object to be used for deserializing.
*
* #param property this is the property/field which is to be serialized
*/
private JsonCollectionDeserializer(BeanProperty property) {
super(property.getType());
this.property = property;
}
#Override
public JsonDeserializer<?> createContextual(DeserializationContext ctxt, BeanProperty property) throws JsonMappingException {
return new JsonCollectionDeserializer(property);
}
#Override
public Object deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
switch (jp.getCurrentToken()) {
case VALUE_STRING:
// value is a string but we want it to be something else: unescape the string and convert it
return JacksonUtil.MAPPER.readValue(StringUtil.unescapeXml(jp.getText()), property.getType());
default:
// continue as normal: find the correct deserializer for the type and call it
return ctxt.findContextualValueDeserializer(property.getType(), property).deserialize(jp, ctxt);
}
}
}
Note that this deserializer will also work if the value actually is an array and not a string, because it delegates the actual deserialization accordingly.
In your example you would now have to annotate your collection field like so:
public class ListResponse {
public String error;
#JsonDeserialize(using = JsonCollectionDeserializer.class)
public ArrayList<ListItem> object;
public ListResponse() {}
}
And that should be it.
Note: JacksonUtil and StringUtil are custom classes, but you can easily replace them. For example by using new ObjectMapper() and org.apache.commons.lang3.StringEscapeUtils.
The register subTypes works!
#JsonTypeInfo(use=JsonTypeInfo.Id.NAME, include=JsonTypeInfo.As.PROPERTY, property="type")
public interface Geometry {
}
public class Point implements Geometry{
private String type="Point";
....
}
public class Polygon implements Geometry{
private String type="Polygon";
....
}
public class LineString implements Geometry{
private String type="LineString";
....
}
GeoJson geojson= null;
ObjectMapper mapper = new ObjectMapper();
mapper.disable(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES);
mapper.registerSubtypes(Polygon.class,LineString.class,Point.class);
try {
geojson=mapper.readValue(source, GeoJson.class);
} catch (IOException e) {
e.printStackTrace();
}
Ran into a similar problem like the following forum post:
http://jersey.576304.n2.nabble.com/parsing-JSON-with-Arrays-using-Jettison-td5732207.html
Using Resteasy 2.0.1GA with Jettison 1.2 and getting a problem marshalling arrays when involving namespace mappings. See code below. Basically if the number of array entries are greater than one and namespace mappings are used. Anybody else run into this problem? The Nabble form poster got around it by writing a custom unmarshaller.
I either need to isolate the Jettison bug or write a Resteasy extension of the JettisonMappedUnmarshaller class (which hands over the namespace mappings and unmarshaller to the Jettison Configuration).
The following code doesn't unmarshall (post step) if the properties variables contains 2 or more entries.
public class Experimenting {
#Path("test")
public static class MyResource {
#XmlAccessorType(XmlAccessType.FIELD)
#XmlType(name = "Property", propOrder = { "name", "value" })
public static class MyProperty {
#XmlElement(name = "Name", required = true)
protected String name;
#XmlElement(name = "Value", required = true)
protected String value;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
}
#XmlType(name = "MyElement", propOrder = { "myProperty" })
#XmlAccessorType(XmlAccessType.FIELD)
#XmlRootElement(name = "MyElement", namespace = "http://www.klistret.com/cmdb/ci/commons")
#Mapped(namespaceMap = { #XmlNsMap(namespace = "http://www.klistret.com/cmdb/ci/commons", jsonName = "com.klistret.cmdb.ci.commons") })
public static class MyElement {
#XmlElement(name = "MyProperty", namespace = "http://www.klistret.com/cmdb/ci/commons")
protected List myProperty;
public List getMyProperty() {
if (myProperty == null) {
myProperty = new ArrayList();
}
return this.myProperty;
}
public void setMyProperty(List myProperty) {
this.myProperty = myProperty;
}
}
#GET
#Path("myElement/{id}")
#Produces(MediaType.APPLICATION_JSON)
public MyElement getMy(#PathParam("id")
Long id) {
MyElement myElement = new MyElement();
MyProperty example = new MyProperty();
example.setName("example");
example.setValue("of a property");
MyProperty another = new MyProperty();
another.setName("another");
another.setValue("just a test");
MyProperty[] properties = new MyProperty[] { example, another };
myElement.setMyProperty(Arrays.asList(properties));
return myElement;
}
#POST
#Path("/myElement")
#Consumes(MediaType.APPLICATION_JSON)
#Produces(MediaType.APPLICATION_JSON)
public MyElement createMy(MyElement myElement) {
List properties = myElement.getMyProperty();
System.out.println("Properties size: " + properties.size());
return myElement;
}
}
private Dispatcher dispatcher;
#Before
public void setUp() throws Exception {
// embedded server
dispatcher = MockDispatcherFactory.createDispatcher();
dispatcher.getRegistry().addPerRequestResource(MyResource.class);
}
#Test
public void getAndCreate() throws URISyntaxException,
UnsupportedEncodingException {
MockHttpRequest getRequest = MockHttpRequest.get("/test/element/44");
MockHttpResponse getResponse = new MockHttpResponse();
dispatcher.invoke(getRequest, getResponse);
String getResponseBodyAsString = getResponse.getContentAsString();
System.out.println(String.format(
"Get Response code [%s] with payload [%s]", getResponse
.getStatus(), getResponse.getContentAsString()));
MockHttpRequest postRequest = MockHttpRequest.post("/test/element");
MockHttpResponse postResponse = new MockHttpResponse();
postRequest.contentType(MediaType.APPLICATION_JSON);
postRequest.content(getResponseBodyAsString.getBytes("UTF-8"));
dispatcher.invoke(postRequest, postResponse);
System.out.println(String.format(
"Post Response code [%s] with payload [%s]", postResponse
.getStatus(), postResponse.getContentAsString()));
}
}
Do you have to use Jettison? If not I would recommend just switching to use Jackson instead; this typically solves array/list related problems (problem with Jettison is that it converts to XML model, which makes it very hard to tell arrays from objects -- there are bugs, too, but it is fundamentally hard thing to get working correctly).