I have a simple pojo where i have one list of strings and default get/set, i have another get so that in json i get 2 different fields
my pojo and test code snippet are below
public static class TestClass{
public ArrayList<String> names = null;
public ArrayList<String> getNames() {
if(null == names) names = new ArrayList<>();
return names;
}
public void setNames(ArrayList<String> names) {
this.names = names;
}
public ArrayList<String> getNames_r() {
return getNames();
}
#Override
public String toString() {
return "TestClass [names=" + names + "]";
}
}
#Test
public void testDeSerializationSimple() throws JsonParseException, JsonMappingException, IOException{
String justSchool = "{\"names\":[\"second\",\"one\",\"two\",\"three\"],\"names_r\":[\"second\",\"one\",\"two\",\"three\"]}";
ObjectMapper myDefaultMapper= new ObjectMapper();
myDefaultMapper.setDateFormat(CoreUtils.COMMON_SIMPLE_DATE_FORMAT)
.setTimeZone(TimeZone.getTimeZone("UTC"))
.enable(SerializationFeature.INDENT_OUTPUT)
.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
TestClass testReadDummy = myDefaultMapper.readValue(justSchool, TestClass.class);
System.out.println(" mapper test read = "+testReadDummy);
//assertEquals(testRead.getListString().size(),4);
System.out.println("list = "+testReadDummy);
assertEquals(testReadDummy.names.size(), 4);
}
Try using the #JsonIgnore annotation in the duplicate of your list so it doesn't get serialized, it would look something like:
#JsonIgnore
public ArrayList<String> getNames_r() {
return getNames();
}
That should get rid of your duplicate field in you serialized JSON.
Hope it helps,
Jose Luis
configuring the mapper to not use getters as setters using
MAPPER.configure(MapperFeature.USE_GETTERS_AS_SETTERS, false);
solved this
Related
I am having some trouble serializing/deserializing my classes below.
My Data class holds a list of other classes.
When I call the serialize/deserialize methods in the Data class, I get the following error:
Caused by: com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of com.amazon.rancor.storage.types.ChildData: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?)
The error comes from the deserialize method. But I also believe the serialization is not working properly. This is what the serialized Data object looks like:
{childData:[{zipCode:{present:true},countryCode:"US"}]
The Optional field is not being serialized properly even though I have set the objectMapper.registerModule(new Jdk8Module()); field
I can't seem to figure out what I am doing wrong. Maybe I need to change something in ChildData and ChildDataV2 class. But I am not sure what.
Any pointers would be appreciated!
public class Data {
private List<ChildData> childData;
private List<ChildDataV2> childDataV2;
private static ObjectMapper objectMapper;
static {
objectMapper = new ObjectMapper();
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
objectMapper.registerModule(new Jdk8Module());
}
public Data() { }
#JsonCreator
public Data(#JsonProperty("childData") final List<ChildData> childData,
#JsonProperty("childDataV2") final List<ChildDataV2> childDataV2) {
this.childData = childData;
this.childDataV2 = childDataV2;
}
public List<ChildData> getChildData() {
return childData;
}
public void setChildData(final List<ChildData> childData) {
this.childData = childData;
}
public List<ChildDataV2> getChildDataV2() {
return childDataV2;
}
public void setChildDataV2(final List<ChildDataV2> childDataV2) {
this.childDataV2 = childDataV2;
}
public String serialize() {
try {
return objectMapper.writeValueAsString(this);
} catch (JsonProcessingException e) {
throw new RuntimeException("Failed to serialize. Data: " + this, e);
}
}
public Data deSerialize(final String data) {
try {
return objectMapper.readValue(data, Data.class);
} catch (IOException e) {
throw new RuntimeException("Failed to deserialize. Data" + data, e);
}
}
}
public class ChildData {
private final String countryCode;
private final Optional<String> zipCode;
public ChildData(final String countryCode, final Optional<String> zipCode) {
this.countryCode = countryCode;
this.zipCode = zipCode;
}
public Optional<String> getZipCode() {
return zipCode;
}
public String getCountryCode() {
return countryCode;
}
}
public class ChildDataV2 extends ChildData {
private final Object struct;
public ChildDataV2(final String cc, final Optional<String> postalCode,
final Object struct) {
super(cc, postalcode);
this.struct = struct;
}
}
The exception is quite clear right? You need to add a default constructor for ChildData or annotate the existing constructor like this:
#JsonCreator
public ChildData(#JsonProperty("countryCode") String countryCode, #JsonProperty("zipCode") Optional<String> zipCode) {
this.countryCode = countryCode;
this.zipCode = zipCode;
}
I am trying to use spring-data-solr in order to access to my Solr instance through my Spring boot application. I have the following bean class:
#SolrDocument(solrCoreName = "associations")
public class Association implements PlusimpleEntityI {
#Id
#Indexed
private String id;
#Indexed
private String name;
#Indexed
private Point location;
#Indexed
private String description;
#Indexed
private Set<String> tags;
#Indexed
private Set<String> topics;
#Indexed
private Set<String> professionals;
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;
}
public Point getLocation() {
return location;
}
public void setLocation(Point location) {
this.location = location;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public Set<String> getTags() {
return tags;
}
public void setTags(Set<String> tags) {
this.tags = tags;
}
public Set<String> getTopics() {
return topics;
}
public void setTopics(Set<String> topics) {
this.topics = topics;
}
public Set<String> getProfessionals() {
return professionals;
}
public void setProfessionals(Set<String> professionals) {
this.professionals = professionals;
}
}
I have implemented the following repository in order to access to the related information:
public interface AssociationsRepository extends SolrCrudRepository<Association, String> {
}
I have created a configuration class which looks like the following one:
#Configuration
#EnableSolrRepositories(basePackages = {"com.package.repositories"}, multicoreSupport = true)
public class SolrRepositoryConfig {
#Value("${solr.url}")
private String solrHost;
#Bean
public SolrConverter solrConverter() {
MappingSolrConverter solrConverter = new MappingSolrConverter(new SimpleSolrMappingContext());
solrConverter.setCustomConversions(new CustomConversions(null));
return solrConverter;
}
#Bean
public SolrClientFactory solrClientFactory () throws Exception {
return new MulticoreSolrClientFactory(solrClient());
}
#Bean
public SolrClient solrClient() throws Exception {
return new HttpSolrClient.Builder(solrHost).build();
}
#Bean
public SolrOperations associationsTemplate() throws Exception {
SolrTemplate solrTemplate = new SolrTemplate(solrClient());
solrTemplate.setSolrConverter(solrConverter());
return solrTemplate;
}
}
Unfortunately, when I try to read an association from my Solr instance I got the following error:
org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.lang.String] to type [org.springframework.data.solr.core.geo.Point]
I don't understand why it is not able to find a converter if I have explicitly defined it in the solrTemplate() method.
This is my POM definition:
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-solr</artifactId>
<version>2.1.4.RELEASE</version>
</dependency>
Thank you for your help.
EDIT:
I've also tried with different BUILD-RELEASEs but they are highly unstable and I've found a lot of errors using them.
Alessandro, as you can see directly in the GeoConverters class on GitHub, the implemented converters are only for:
org.springframework.data.geo.Point
and not for:
org.springframework.data.solr.core.geo.Point
Simply use this class and you don't even need a custom converter for this. Spring Data for Solr will perform the conversion for you.
I'm using a slightly patched version of the 3.0.0 M4, but I'm pretty sure this solution should apply seamlessly also to your case.
I am making a class to deal with a friend list scenario using an ArrayList and I'm not sure what I have done wrong. The "java.lang.NullPointerException" occurred the moment I called the addFriend method and I can't seem to troubleshoot exactly why this is happening. Please give me some hints in the right direction!
public class Person {
private String name;
private ArrayList<String> friends;
public Person(String name) {
this.name = name;
this.friends = friends;
}
public String getName() {
return this.name;
}
public void addFriend(String friend) {
friends.add(friend);
}
public boolean hasFriend(String name) {
for(String friend : this.friends) {
if(name.equals(friend)) {
return true;
}
}
return false;
}
public String getFriends() {
String stringOfFriends=friends.toString();
return stringOfFriends;
}
public String unfriend(String friend) {
if (friends.contains(friend)) {
friends.remove(friend);
}
return friends.toString();
}
}
Your Constructor has to initialze the Arraylist:
public Person(String name) {
this.name = name;
this.friends = new ArrayList<String>();
}
In your current version, you assign the ArrayList "friends" to itself. That means you basically call this.frinds = this.friends and this.friends is not initialzed yet hence the NullpointerException.
In your constructor this.friends = friends; doesn't make sense. Make like this
public Person(String name,ArrayList<String> friends) {
this.name = name;
this.friends = friends;
}
Then pass the actual arraylist to the constructor.
You need to initialize your array list. Like private ArrayList<String> friends = new ArrayList<String>(); or in the constructor as below:
public Person(String name) {
this.name = name;
this.friends = new ArrayList<String>();
}
I'm using fasterXML's Jackson (v2.3.3) library to deserialize and serialize a custom class. The class is defined as following:
public class Person {
private String name;
private Map<String, Person> children;
// lots of other fields of different types with no issues
}
the keys of map children are the name fields. I receive data in JSON with each person object structured as following (I have omitted the other fields):
{"name":"Bob", "children":[{"name":"Jimmmy"},{"name":"Judy"}]}
(Many Fields such as children are optional and aren't serialized when null)
I have been storing children in a List<Person> so far with no issues, but many new use cases need to have access to the set of names or to a specific Person using his name as key. This is why I have decided to store them using a Map.
After some research, I think the best way is to use Annotations #JsonDeserialize and #JsonSerialize with a JsonDeserializer and JsonSerializer as parameter respectively for the field children:
public class Person {
private String id;
#JsonSerialize(using=MySerializer.class)
#JsonDeserialize(using=MyDeserializer.class)
private Map<String, Person> friends;
// lots of other fields
}
My question is: Does such a JsonSerializer/JsonDeserializer exist and if not, how do I define one?
edit: I have started implementing a custom Deserializer, but I get this exception:
com.fasterxml.jackson.databind.JsonMappingException: Class has no default (no arg) constructor
which is weird because I have defined a default constructor. Here is my custom Deserializer:
public class MyDeserializer extends JsonDeserializer<Map<String, Person>> {
public MyDeserializer() {
}
#Override
public Map<String, Person> deserialize(JsonParser jp, DeserializationContext ctxt)
throws IOException, JsonProcessingException {
JsonNode personsNodeArray = jp.getCodec().readTree(jp);
Map<String, Person> newChildren = null;
if (personsNodeArray.isArray() && personsNodeArray.size() > 0) {
newChildren = new HashMap<String, Person>();
for (JsonNode personNode : personsNodeArray) {
String id = personNode.get("name").asText();
// jsonMapper is a default ObjectMapper
newChildren.put(id, jsonMapper.readValue(personNode.toString(), Person.class));
}
}
return newChildren;
}
}
You can also consider reading children information as a collection of persons with subsequent conversion into a map. You can define a setter method (or a constructor parameter) to accept a List<Person> and then put each element into the Map<String, Person> children field. That would avoid unnecessary complexity of custom serialisation.
Here is an example:
public class JacksonChildren {
public static final String JSON = "{\"name\":\"Bob\", \"children\":[{\"name\":\"Jimmmy\"}," +
"{\"name\":\"Judy\"}]}";
public static class Person {
public String name;
private Map<String, Person> children = new HashMap<>();
public void setChildren(final List<Person> children) {
for (Person p : children) {
this.children.put(p.name, p);
}
}
#Override
public String toString() {
return "Person{" +
"name='" + name + '\'' +
", children=" + children +
'}';
}
}
public static void main(String[] args) throws IOException {
ObjectMapper mapper = new ObjectMapper();
System.out.println(mapper.readValue(JSON, Person.class));
}
}
Output:
Person{name='Bob', children={Judy=Person{name='Judy', children={}}, Jimmmy=Person{name='Jimmmy', children={}}}}
Jackson by default includes all public getters. But if I have hundreds of getters and I want to serialize just few of them, how can I achieve this?
I don't want to use #JsonIgnore annotation to specify all others hundred properties.
You can use Jackson's views or filters to select the serialization form of your object. Here is an example using the filter which picks up the properties with the given names:
public class JacksonFilter {
#JsonFilter("filter")
public static class Bean {
private final String field1;
private final String field12;
private final String field10;
private final String field100;
public Bean(String field1, String field12, String field10, String field100) {
this.field1 = field1;
this.field12 = field12;
this.field10 = field10;
this.field100 = field100;
}
public String getField1() {
return field1;
}
public String getField12() {
return field12;
}
public String getField10() {
return field10;
}
public String getField100() {
return field100;
}
}
public static void main(String[] args) throws JsonProcessingException {
ObjectMapper mapper = new ObjectMapper();
SimpleFilterProvider filters = new SimpleFilterProvider();
filters.addFilter("filter",
SimpleBeanPropertyFilter.serializeAllExcept("field12", "field100"));
mapper.setFilters(filters);
Bean bean = new Bean("A", "B", "C", "D");
System.out.println(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(bean));
}
}
Output:
{
"field1" : "A",
"field10" : "C"
}