Jackson throwing an exception in deserialization with protected access modifier.
I am trying to deserialize one object then accessing protected properties of parent class is throwing exception.
Class com.fasterxml.jackson.databind.deser.impl.FieldProperty can not
access a member "protected"
Make sure that Jackson can see protected fields. E.g.
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import static com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility.PROTECTED_AND_PUBLIC;
#JsonAutoDetect(fieldVisibility = PROTECTED_AND_PUBLIC)
class Person {
protected String name;
}
Or define getters and setters as needed. E.g. :
class Person {
protected String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Related
When im tryin got do a Post request through my JAX-RS API it always sends a null value. I dont know if the Jackson annotations are incorrect or if i need to use an ObjectMapper.
These are my classes:
public class ClassA{
private String name;
private ClassB classB;
public ClassA(){}
public ClassA(String name, ClassB classB){
this.name = name;
this.classB = classB;
}
#JsonGetter
public String getName(){ return name; }
#JsonGetter
public ClassB getClassB(){ return classB; }
and this is the classB
public class ClassB{
#JsonProperty("type")
private String type;
#JsonProperty("number")
private int number;
public ClassB(){}
#JsonPropertyOrder({"type, number"})
public ClassB(String type, int number){
this.type= type;
this.number= number;
}
#JsonGetter
public String getType(){ return type; }
#JsonGetter
public int getNumber(){ return number; }
My JSON file:
{
"type": "typeExample;
"classB": {
"type": "classBTypeExample";
"int": 10;
}
}
I want Jackson to read the file and then add an Object type ClassA to a list (the problem is that is not even reading it)
This is the API code:
#Path("/path")
public class Requests {
private Set<ClassA> classesA = Collections.newSetFromMap(Collections.synchronizedMap(new LinkedHashMap<>()));
#GET
public Set<ClassA> list() {
return classesA;
}
#POST
public Set<ClassA> add(ClassA classA){
classesA.add(classA);
return classesA;
}
}
I already added the quarkus.jackson.fail-on-unknown-properties=true to the application.properies file
It was a simple thing that i didnt notice. I forgot to set the values on the constructer. So i just had to add the #ConstructorProperties({}) to the classes constructors and it worked out.
Rest Controller:
#RequestMapping(value = "/admin/rest/new-subscriptions")
public List<NewSubscriptionDTO> getNewSubscriptions() {
NewSubscriptionDTO dto = new NewSubscriptionDTO();
dto.setId("54");
dto.setName("John Doe");
return Arrays.asList(dto);
}
NewSubscriptionDTO:
package dermatica.web.admin.rx;
import com.fasterxml.jackson.annotation.JsonProperty;
import org.joda.time.DateTime;
import java.io.Serializable;
public class NewSubscriptionDTO implements Serializable {
private String id;
private String name;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
I get the following exception:
no properties discovered to create BeanSerializer (to avoid exception,
disable SerializationFeature.FAIL_ON_EMPTY_BEANS)
If I annotate the fields with #JsonProperty it work fine.
Is there a way for the serialization to work automatically without needing this annotation?
#JsonProperty auto-generates a getter/setter that Jackson uses to read/write to the fields during serialization/deserialization. Here are some alternative approaches:
Provide your own public getters/setters for all fields
Make the fields public, generally frowned upon, but if you're creating a simple DTO, that may be acceptable.
Setting ObjectMapper Visibility for FIELD to ANY (see here)
Disable the FAIL_ON_EMPTY_BEANS exception (see here)
Given that your DTO class has getters and setters, this should work without #JsonProperty. I wasn't able to reproduce the exact error message you showed, but here are some suggestions that may help:
[Controller] Explicitly specify the method type as GET, either using method = GET or #GetMapping - not necessary, but it's good to be explicit
[Controller] Make sure you annotate the controller class with #RestController, indicating the response is serialized to JSON and wrapped in an HttpResponse object.
[DTO] You don't need to extend Serializable (see here).
The final controller would look like this:
#RestController
public class MyController {
#GetMapping(value = "/admin/rest/new-subscriptions")
public List<MyDTO> getDTO() {
MyDTO dto = new MyDTO();
dto.setId("54");
dto.setName("John Doe");
return Collections.singletonList(dto);
}
}
Response:
[{"id":"54","name":"John Doe"}]
EclipseLink version is 2.5.1
We've moved from GlassFish web-server to TomCat. This made us switch to static weaving because with TomCat dynamic weaving doesn't really work that easy.
Now that static weaving works, it seems to work quite a bit differently.
If I have an entity which sets some property directly in the constructor:
class Entity {
#Column
private String name;
public Entity() {
name = "something";
}
public String getName() {
return name;
}
}
Long story short this test will fail:
Entity e = new Entity();
assertEquals("something", e.getName()); // e.getName() returns null
This happens because getName(), after weaving, is not returning this.name anymore. Instead it calls a routing for initialization (if it's needed) and (I guess) gets the value of the property from some underlying HashMap.
But constructor is not being weaved, I even have looked into the sources of weaver and seems to be explicitly opting out of this:
/**
* Construct a MethodWeaver and allow it to process the method.
*/
#Override
public MethodVisitor visitMethod(int access, String methodName, String desc, String signature, String[] exceptions) {
MethodVisitor mv = super.visitMethod(access, methodName, desc, signature, exceptions);
if (!alreadyWeaved) {
// skip constructors, they will not changed
if (!"<init>".equals(methodName) && !"<cinit>".equals(methodName)) {
// remaining modifications to the 'body' of the class are
// delegated to MethodWeaver
mv = new MethodWeaver(this, methodName, desc, mv);
}
}
return mv;
}
The question is, maybe I miss something here? Is it the actual reality with EclipseLink 2.5.1 that you can't use properties directly in entity's own ctor? (and it's not even mentioned anywhere, not googlable at least)
It turns out yes, we can.
But there was a problem that led us to the property being not visible to the getter.
We actually have MappedSuperclass inheritance here and we were shadowing this field in the child class. Essentially this:
class A {
#Column()
protected String name;
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
}
class B extends A {
#Column()
protected String name;
// no #Override here
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
}
So we were just shadowing the property.
I have the following interface
#JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "className")
public interface InfoChartInformation {
public String name();
}
And the following implementation (enum):
public class InfoChartSummary {
public static enum Immobilien implements InfoChartInformation {
CITY, CONSTRUCTION_DATE;
}
public static enum Cars implements InfoChartInformation {
POWER, MILEAGE;
}
}
Then I use all of It in the following entity:
#Entity(noClassnameStored = true)
#Converters(InfoChartInformationMorphiaConverter.class)
public class TestEntity{
#Id
public ObjectId id;
#Embedded
public List<InfoChartInformation> order;
}
Jackson, in order to detect the type on the unmarshalling time, will add to every enum on the list the className.
I thought morphia would do the same, but there's no field className in the List of enum and the unmarshalling cannot be done correctly: java.lang.RuntimeException: java.lang.RuntimeException: java.lang.RuntimeException: java.lang.ClassCastException: java.lang.String cannot be cast to com.mongodb
.DBObject
I guess the correct behavior should be to save all the enum route (package+name), not only the enum name. At least in that way the unmarshalling could be performed. There's a way morphia supports that by default or I need to create my own converter (similar to this) ?
I tried creating a Custom Converter:
public class InfoChartInformationMorphiaConverter extends TypeConverter{
public InfoChartInformationMorphiaConverter() {
super(InfoChartInformation.class);
}
#Override
public Object decode(Class targetClass, Object fromDBObject, MappedField optionalExtraInfo) {
if (fromDBObject == null) {
return null;
}
String clazz = fromDBObject.toString().substring(0, fromDBObject.toString().lastIndexOf("."));
String value = fromDBObject.toString().substring(fromDBObject.toString().lastIndexOf(".") + 1);
try {
return Enum.valueOf((Class)Class.forName(clazz), value);
} catch (ClassNotFoundException e) {
return null;
}
}
#Override
public Object encode(final Object value, final MappedField optionalExtraInfo) {
return value.getClass().getName() + "." + ((InfoChartInformation) value).name();
}
}
Then, I added the converter information to morphia morphia.getMapper().getConverters().addConverter(new InfoChartInformationMorphiaConverter());.
However, when serializing (or marshalling) the object to save it into the database, the custom converter is ignored and the Enum is saved using the default Morphia converter (only the enum name).
If I use in the TestEntity class only an attribute InfoChartInformation; instead of the List<>InfoChartInformation>, my customer converter will work. However I need support for List
Use:
public class InfoChartInformationMorphiaConverter extends TypeConverter implements SimpleValueConverter
It is a marker interface required to make your Convertor work.
I got some troubles for attribute binding in JSF 1.2 with EL 1.0
public class Bean {
private String name;
public String getName() {
return name;
}
public Bean setName(String name)
this.name = name;
return this;
}
XHTML that give me "Property 'name' not writable" error on form submit:
..
<h:inputText value="#{bean.name}" />
..
Why? It is a 3rd party lib, there is any workaround to solve that case?
Change signature of setName method like this
public void setName(String name)
this.name = name;
}
If you want second constructor in your Bean class, then it should be designed like this
public Bean (String name)
this.name = name;
}
I found a workaround for that case, but clearly it's not the most elegant way to do:
Create a "pseudo extension" of Bean class:
public class BeanExtension {
private Bean instance = new Bean();
public String getName() {
return instance.getName();
}
public void setName(String name)
instance.setName(name);
}
// omitted instance getter and setter methods
}
Since I wanted to override setName method return to "void", now I must use bean.instance to access it attributes, and bean.name to bind name on JSF with EL.