Develop Reference

JsonArray field in a JsonObject to Java Object

Below is my JSON data. I want to convert this to POJOs to store the Name,id,profession in a header table and the respective Jsonarray field in a child table.
JSON:
{
"Name": "Bob",
"id": 453345,
"Profession": "Clerk",
"Orders": [
{
"Item": "Milk",
"Qty": 3
},
{
"Item": "Bread",
"Qty": 3
}
]
}
Entity classes:
public class User {
private String name;
private Integer id;
private String Profession;
private JsonArray Orders;
private UserCart userCart;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getProfession() {
return Profession;
}
public void setProfession(String profession) {
Profession = profession;
}
public JsonArray getOrders() {
return Orders;
}
public void setOrders(JsonArray orders) {
Orders = orders;
}
public UserCart getUserCart() {
return userCart;
}
public void setUserCart(UserCart userCart) {
this.userCart = userCart;
}
}
public class UserCart {
private String item;
private Integer qty;
public String getItem() {
return item;
}
public void setItem(String item) {
this.item = item;
}
public Integer getQty() {
return qty;
}
public void setQty(Integer qty) {
this.qty = qty;
}
}
But when I do below; I get error
Cannot deserialize instance of org.json.JSONArray out of START_ARRAY
token
User user = new User();
JsonNode data = new ObjectMapper().readTree(jsonString);
user = headerMap.readValue(data.toString(), User.class);
How do I go about assigning the entire JSON to both the Java objects ?

Use List<UserCart> for array data in json and use #JsonProperty for mapping different json node name to java object field. No need to use extra field (JsonArray Orders) anymore.
#JsonProperty("Orders")
private List<UserCart> userCart;

JSON parse error: Cannot deserialize instance of.. out of START_ARRAY token

I know there are a few questions on stackoverflow regarding this problem. But I have have been spending hours trying to resolve this error without any success.
I am using the mysql database to store the values.
I keep on getting the error message from the
com.example.springboot.Recipe file.
This is springboot recipe file
package com.example.springboot;
import com.example.springboot.Recipe;
import javax.persistence.*;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.NotNull;
#Entity // This tells Hibernate to make a table out of this class
public class Recipe {
public Recipe(){
}
public Recipe(Integer id, String name, String description, String type, Integer preptime, Integer cooktime, String content, Integer difficulty){
this.id = id;
this.name = name;
this.description = description;
this.type = type;
this.preptime = preptimee;
this.cooktime = cooktime;
this.content = content;
this.difficulty = difficulty;
}
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private Integer id;
private String name;
private String description;
private String type;
private Integer preptime;
private Integer cooktime;
#Column(columnDefinition = "TEXT")
private String content;
private Integer difficulty;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getTitle() {
return name;
}
public void setTitle(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public Integer getDifficulty() {
return difficulty;
}
public void setDifficulty(Integer difficulty) {
this.difficulty = difficulty;
}
public Integer getCookingtime() {
return cooktime;
}
public void setCookingtimeime(Integer cooktime) {
this.cooktime = cooktime;
}
public Integer getPreparationtime() {
return preptime;
}
public void setPreparationtime(Integer preptime) {
this.preptime = preptime;
}
}
Main Controller:
#PutMapping("/recipes/edit/{id}")
void updateRecipe2(#PathVariable int id, #RequestBody Recipe recipe ) {
Recipe recipe_ = recipeRepository.findById(id).get();
recipe_.setTitle(recipe.getTitle());
System.out.println("sss " + recipe.getname());
System.out.println("change");
recipeRepository.save(recipe_);
}
service.ts:
updateRecipe2 (id: number, recipe: any): Observable<any > {
const url = `${this.usersUrl}/edit/${id}`;
return this.http.put(url ,recipe);
}
where the updateRecipe2 gets called:
save(): void {
const id = +this.route.snapshot.paramMap.get('name');
this.recipeService.updateRecipe2(id, this.recipes)
.subscribe(() => this.gotoUserList());
}
as soon as the user clicks save this functions saves the changes made.
I hope the code snippets that I provided are enough to help solve the problem.
Thank you in advance.
I am building a rest api with spring boot and I am using angularjs as it's frontend. I am pretty new to web-development.

You are sending a list of recipes to an api endpoint that expects a single recipe object.
Your options are:
Send only one recipe object at a time, for example:
this.recipeService.updateRecipe2(id, this.recipes[0])
OR: create a new API endpoint to accept a list of recipes, to edit them in "batch"
#PutMapping("/recipes/edit")
void updateRecipes(#RequestBody List<Recipe> recipe ) {

my Example:
Use:
#PostMapping
Code:
public void setTransacciones(List<Transacciones> transacciones) {
this.transacciones = transacciones;
}
CodeBean:
public class Transacciones {
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
private String text;
}
Post(raw):
{
"transacciones" : [ {"text" : "1"}, {"text" : "2"} ]
}
Result:
{
"transacciones": [
{
"transaccionId": 2,
"text": "1"
},
{
"transaccionId": 3,
"text": "2"
}
]
}
BINGO!!

UnrecognizedPropertyException: Unrecognized field "sections"

I'm using Jackson as part of a spring boot app. I am turning JSON into Java, and I am getting this error. I did some research, but I still don't understand what is going wrong or how to fix it.
Here is the JSON fragment:
"dataBlock": {
"sections": [
{
"info": "",
"prompt": "",
"name": "First Section",
"sequence": 0,
"fields": [],
"gatingConditions": [],
"guid": "480d160c-c34f-4022-97b0-e8a1f28c49ae",
"id": -2
}
],
"prompt": "",
"id": -1,
"name": ""
}
So my Java object for this "dataBlock" element:
public class DataBlockObject {
private int id;
private String prompt;
private String name;
private List<SectionObject> sections;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getPrompt() {
return prompt;
}
public void setPrompt(String prompt) {
this.prompt = prompt;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<SectionObject> getSections() {
return sections;
}
public void setSections(List<SectionObject> sections) {
this.sections = sections;
}
}
And the Section object is this:
public class SectionObject {
private int id;
private String name;
private String prompt;
private String info;
private int sequence;
private List<FieldObject> fields;
private List<GatingConditionObject> gatingConditions;
private String guid;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPrompt() {
return prompt;
}
public void setPrompt(String prompt) {
this.prompt = prompt;
}
public String getInfo() {
return info;
}
public void setInfo(String info) {
this.info = info;
}
public int getSequence() {
return sequence;
}
public void setSequence(int sequence) {
this.sequence = sequence;
}
public List<FieldObject> getFields() {
return fields;
}
public void setFields(List<FieldObject> fields) {
this.fields = fields;
}
public List<GatingConditionObject> getGatingConditions() {
return gatingConditions;
}
public void setGatingConditions(List<GatingConditionObject> gatingConditions) {
this.gatingConditions = gatingConditions;
}
public String getGuid() {
return guid;
}
public void setGuid(String guid) {
this.guid = guid;
}
}
So it seems to me that Jackson would make a DataBlockObject, map the obvious elemenets, and create an array that I have clearly marked as a List named sections. -- just like the JSON shows.
Now the error is:
Caused by: com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "sections" (class com.gridunity.workflow.bean.json.SectionObject), not marked as ignorable (8 known properties: "gatingConditions", "sequence", "prompt", "fields", "id", "info", "guid", "name"])
Now according to that error it would seem that one of my 8 elements should be named "sections" - But that's not one of my elements. It clearly has a problem with my List of Sections, but I cant figure out what it is.
Can someone explain WHY this is happening, especially sence it looks like I have my structure correct, and how to fix this. I have seen this on other posts:
objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
But that seems incredibly wrong as I know all of my properties.

It looks like the JSON itself has another sections field in one or more of the dataBlock.sections items. If you don't have control over the construction of the JSON object, you'll need to add a #JsonIgnoreProperties annotation on the SectionObject class so that when the JSON object has fields that aren't specified in the POJO, it won't throw an error during deserialization.
#JsonIgnoreProperties(ignoreUnknown = true)
public class SectionObject {
// class members and methods here
}

Dynamically add property:value in JSON through rest services

How do we create a json property:value dynamically by taking them as inputs from the user through a REST service, without having to have fields to hold the value.
Basically, the present output is :
{
"name": "X",
"price": "X",
"ticker": "X",
"status": "X",
"supplier": "X",
"attribute": [{
"key": "index",
"value": "Nasdaq"
},
{
"key": "priority",
"value": "high"
}
]
}
Required output is :
{
"name": "X",
"price": "X",
"ticker": "X",
"status": "X",
"supplier": "X",
"attribute": [{
"index": "Nasdaq"
},
{
"priority": "high"
}
]
}
Here, index and Nasdaq are the values given by the user, which is the key-value pair that is to be added to the attribute list.
The two POJO's used :
Stock.java
#XmlRootElement
public class Stock {
public Stock() {
}
public Stock(String name, double price, String ticker, String status, String supplier, List<KV> attribute) {
super();
this.name = name;
this.price = price;
this.ticker = ticker;
this.status = status;
this.supplier = supplier;
this.attribute = attribute;
}
private String name;
private double price;
private String ticker;
private String status;
private String supplier;
private List<KV> attribute;
public List<KV> getAttribute() {
return attribute;
}
public void setAttribute(List<KV> attribute) {
this.attribute = attribute;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public String getTicker() {
return ticker;
}
public void setTicker(String ticker) {
this.ticker = ticker;
}
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
public String getSupplier() {
return supplier;
}
public void setSupplier(String supplier) {
this.supplier = supplier;
}
}
And :
KV.java
public class KV {
private String key;
private String value;
public KV(String key, String value) {
super();
this.key = key;
this.value = value;
}
public String getKey() {
return key;
}
public void setKey(String key) {
this.key = key;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
}
Would prefer answers relating to usage of annotations or changes in the rest service, and not text processing at the end.

Okay, once you get the response you are getting currently then instead of a class "public class KV {} ", you can create a Hashmap,
& key of the Hashmap can hold the index/priority etc & value can hold Nasdaq/high.
Also name the Hashmap variable as "attribute".
So that you can extract the data from API using your current structure & then can convert it to one as I said above & send the response.

Try using Attributes class in java
Instead of defining a list of object you can just define
Attribute attributes;
For more details about how Attribute class works visit https://docs.oracle.com/javase/8/docs/api/org/xml/sax/Attributes.html

Objectify Java Reference

#Entity
public class Category {
#Id
private Long id;
private String name;
private String description;
#Load
private List<Ref<Subcategory>> subcategories = new ArrayList<Ref<Subcategory>>();
#Load
private Ref<Image> image;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public List<Subcategory> getSubcategories() {
List<Subcategory> scs = new ArrayList<Subcategory>();
for (Ref<Subcategory> sc : this.subcategories) {
scs.add(sc.get());
}
return scs;
}
public void setSubcategory(Subcategory subcategory) {
this.subcategories.add(Ref.create(subcategory));
}
public Image getImage() {
if(image != null) {
return image.get();
}
return null;
}
public void setImage(Image image) {
this.image = Ref.create(image);
}
}
#Entity
public class Subcategory {
#Id
private Long id;
private String name;
private String description;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
public class CategoryDTO {
private Long id;
#NotNull
private String name;
private String description;
private List<Subcategory> subcategories = new ArrayList<Subcategory>();
private Long imageId;
public CategoryDTO() {
}
public CategoryDTO(Category category) {
this.id = category.getId();
this.name = category.getName();
this.description = category.getDescription();
this.subcategories = category.getSubcategories();
if (category.getImage() != null) {
this.imageId = category.getImage().getId();
}
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public List<Subcategory> getSubcategories() {
return subcategories;
}
public void setSubcategories(List<Subcategory> subcategories) {
this.subcategories = subcategories;
}
public Long getImageId() {
return imageId;
}
public void setImageId(Long imageId) {
this.imageId = imageId;
}
}
CategoryDAO
public class CategoryDAO {
private static final Logger log = Logger.getLogger(CategoryService.class.getName());
public static QueryResultIterator<Category> getCategories() {
QueryResultIterator<Category> categories = ofy().load().type(Category.class).iterator();
return categories;
}
}
public class SubcategoryDAO {
public static Subcategory createSubcategory(Long categoryId, Subcategory data) {
// save sub category
Subcategory subcategory = new Subcategory();
if (data.getName() != null) {
subcategory.setName(data.getName());
}
if (data.getDescription() != null) {
subcategory.setDescription(data.getDescription());
}
ofy().save().entity(subcategory).now();
Category category =
ofy().load().type(Category.class).id(categoryId).get();
category.setSubcategory(subcategory);
ofy().save().entity(category).now();
return subcategory;
}
}
CategoryService
#Path("/categories")
public class CategoryService {
#GET
#Produces(MediaType.APPLICATION_JSON)
public String getCategories() {
try {
List<CategoryDTO> categories = new ArrayList<CategoryDTO>();
QueryResultIterator<Category> cats = CategoryDAO.getCategories();
while (cats.hasNext()) {
categories.add(new CategoryDTO(cats.next()));
}
Map<String, List<CategoryDTO>> map = new HashMap<String, List<CategoryDTO>>();
map.put("categories", categories);
return Helper.prepareResponse(map);
} catch (Exception e) {
LogService.getLogger().severe(e.getMessage());
throw new WebApplicationException(500);
}
}
}
Problem:-
When i hit getCategories service, it is showing unexpected behaviour.Instead of showing all the subcategories, it is showing random no of different subcategories every time.
For example say,
first i save a category "c"
then i save subcategories "sa", "sb" and "sc"
On hitting getCategry service,
Expected Behaviour -
{
"status": 200,
"categories" : [{
"name":a,
"subcategories": [
{
"name":"sa"
},
{
"name":"sb"
},
{
"name":"sc"
}
]
}]
}
Outputs i get is something like this -
{
"status": 200,
"categories" : [{
"name":a,
"subcategories": [
{
"name":"sa"
},
{
"name":"sc"
}
]
}]
}
or
{
"status": 200,
"categories" : [{
"name":a,
"subcategories": [{
"name":"sb"
}]
}]
}

To summarize this question, you're performing a query (give list of all categories) and getting back inconsistent results.
This is the system working as advertised. Read this: https://cloud.google.com/appengine/docs/java/datastore/structuring_for_strong_consistency
Eventual consistency is something that you learn to live with and work around when you need it. There is no way to force a query to be strongly consistent without changing the structure of your data - say, put it under a single entity group - but that has repercussions as well. There is no free lunch if you want a globally replicated, infinitely-scalable database.
In addition to eventual consistency, the datastore has no defined ordering behavior if you do not specify a sort order in your query. So that might add to your confusion.

Welcome to the wonderful world of eventual consistency. When I encountered something like this, using ObjectifyService.begin() instead of ObjectifyService.ofy() resolved it. Unlike ofy(), begin() gets you fresh data every time.