I have got two main model classes: Customer and Product
public class Customer {
String name;
String surname;
int age;
BigDecimal cash;
}
public class Product {
String name;
Category category;
BigDecimal price;
}
I want to build json file with Map<Customer, List<Product>>
When I write to json file data with my method which works correct - I am sure about this - the json file shows this syntax
{
"Customer{name\u003d\u0027Custo1\u0027, surname\u003d\u0027Surname\u0027, age\u003d18, cash\u003d1200}": [
{
"name": "prod1",
"category": "CLOTHES",
"price": 12000
},
{
"name": "prod2",
"category": "ELECTRONIC",
"price": 15000
}
]
}
Then when i want to read this file, the error Exception in thread "main" java.util.NoSuchElementException: No value present occurs so I think that the Customer syntax from json file is not recognized.
So I tried to write data to json file on my own with this syntax below, but it does not work
[
{
"name": "Abc",
"surname": "Def",
"age": 14,
"cash": "2000"
}
:
[
{
"name": "prod1",
"category": "CLOTHES",
"price": 12000
},
{
"name": "prod2",
"category": "ELECTRONIC",
"price": 15000
}
]
]
json converter method:
public void toJson(final T item) {
try (FileWriter fileWriter = new FileWriter(jsonFilename)) {
fileWriter.write(gson.toJson(item));
} catch (Exception e) {
throw new ValidatorException(e.getMessage());
}
}
#Tom is right on the issues you've faced with. I'll explain why and suggest one more solution.
Your first JSON is technically a valid JSON but it cannot be deserialized, because the map keys are results of the Customer.toString() method Gson uses by default. This is why it looks weird, acts like a debug string, and can't be deserialized back: there it is almost always no way to restore an object from the toString() result (toString is designed mostly for debugging/logging purposes providing basic information regarding the state of a particular object that does not need to expose its all internals at all).
Your second JSON is invalid JSON. Period.
Tom's suggestion of making the list of products a part of the customer class is totally fine. Having it implemented like that lets you to serialize everything as a list like this:
[
{
"name": "john",
"products": [
{"name": "prod1"},
{"name": "prod2"}
]
}
]
Hint: separating domain objects (Customer and Product) and representation objects for data transfer (CustomerDto and ProductDto) is usually a fine idea too since it allows to create representation for any concrete representation implementation (one for various JSON implementation libraries, two for other-format-oriented tools, third for persistence, four for UI views, etc), so it might be implemented like converting Map<Customer, List<Product>> to List<CustomerDto> and back (possibly by using mapper-generators like MapStruct).
If for whatever reason it is not possible to reorganize your domain classes or create Gson-friendly DTO-mappings, or you're fine to keep it as simple as possible and you're fine with having not that trivial JSON structure (as long as you understand implications of the format in this solution: evolution, distribution, etc), then you can enable special Gson mode to support this kind of maps. It generates valid JSONs that can be serialized and deserialized back, but the way it is implemented looks a bit of anti-pattern to me because of losing semantics due to using arrays as the data container.
#AllArgsConstructor
#EqualsAndHashCode
#ToString
final class Customer {
final String name;
}
#AllArgsConstructor
#EqualsAndHashCode
#ToString
final class Product {
final String name;
}
public final class MapTest {
private static final Gson gson = new GsonBuilder()
.enableComplexMapKeySerialization()
.create();
private static final TypeToken<Map<Customer, List<Product>>> customerToProducts = new TypeToken<Map<Customer, List<Product>>>() {};
#Test
public void test() {
final Map<Customer, List<Product>> ordersBefore = ImmutableMap.of(
new Customer("john"), ImmutableList.of(new Product("prod1"), new Product("prod2"))
);
final String json = gson.toJson(ordersBefore, customerToProducts.getType());
Assertions.assertEquals("[[{\"name\":\"john\"},[{\"name\":\"prod1\"},{\"name\":\"prod2\"}]]]", json);
final Map<Customer, List<Product>> ordersAfter = gson.fromJson(json, customerToProducts.getType());
Assertions.assertEquals(ordersBefore, ordersAfter);
}
}
Note that it generates JSON like this (index 0 means the key, index 1 means the value):
[
[
{"name": "john"},
[
{"name": "prod1"},
{"name": "prod2"}
]
]
]
Related
I have the following json
{
"id": "1111",
"match": {
"username1": {
"id": "1234",
"name": "alex"
},
"username2": {
"id": "5678",
"name": "munch"
}
}
}
To deserialize it, I have the following data model class.
class json{
String id;
Match match;
}
class Match {
private Map<String,Profile> profiles
}
class Profile{
private String id;
private String name;
}
I am not getting any deserialization error when I am using gson but the
profiles variable is coming as null.
This is how I am deserializing.
var json = gson.fromJson(data,json.class)
inside the match object there can be a dynamic number of usernames not just two . Why am I getting profile object as null and how can I correctly populate it?
Making changes to json is the last resort here. I can make any other required changes.
The issue is your model. You don't need Match because profiles does not really exist in your JSON. You just json (this one with small changes) and Profile:
class json{
String id;
Map<String,Profile> match;
}
This will work.
So i am trying to build a json to send data to the body of my restassured request, like this structure here:
{
"id": 1,
"category": {
"id": 1,
"name": "duch"
},
"name": "benny",
"photoUrls": [
"string"
],
"tags": [
{
"id": 0,
"name": "string"
}
],
"status": "available"
}
So it is as simple as to copy this as string to the body of the request and i am done, i don't want that at all.
Is there a framework of sorts to give this structure and to change the data dynamically somehow?
I don't want this: (for example)
given().body("{\r\n\"city\": \"Hod Hasharon\",\r\n\"description\": \"Automation Hotel\",\r\n\"name\":\"Nir Great hotel\",\r\n\"rating\":5\r\n}")
.when().post("http://localhost:8090/example/v1/hotels").then().statusCode(201);
I want to be more flexible here, to reference some kind of object (A template with the option to change the data in some places?) that handles this stuff, is there something like that?
I think what you need is using POJO and Jackson to serialize it to json.
public class Payload {
private int id;
private String name;
private List<Tag> tags; //Tag is another class you need to create the same way
//getters, setters
}
And then using objects as payload in your request:
Payload payload = new Payload();
payload.setId(123);
payload.setName("John");
given().contentType("application/json").body(payload).when().post("http://example.com");
Also don't forget to add jackson-databind dependency to your project.
There's more about that in official documentation here: https://github.com/rest-assured/rest-assured/wiki/Usage#object-mapping
I have to deserialise below Json
{
"Student": [
{
"Number": "12345678",
"Name": "abc"
"Country": "IN",
"AreaOfInterest": [
{
“FootBall”: “Yes”,
“Cricket”: “No”
}
]
}
],
"hasMore": false,
"links": [
{
"rel": "self",
"kind": "collection"
}
]
}
into below POJO
class {
private String number;
private String name;
private String footBall;
}
I have written Gson custom deserialiser to lift up AreaOfInterest as below
public List<? extends Student> deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
var jsonObject = json.getAsJsonObject();
Stream<JsonElement> student = StreamSupport.stream(jsonObject.getAsJsonArray("Student").spliterator(), true);
Stream<JsonElement> areaOfInterest = StreamSupport.stream(jsonObject.getAsJsonArray("Student").get(0).getAsJsonObject().get("AreaOfInterest").getAsJsonArray().spliterator(), true);
Stream.concat(student,areaOfInterest)
.map(it -> context.deserialize(it, Student.class))
.map(Student.class::cast)
.collect(List.collector())
}
But deserialiser returning two objects of Student instead of one, one is all fields are null except footBall other is actual student except footBall as null, any help how to get single object with all the fields will be of great help, thanks in advance.
This won't be your exact answer, but it might be simpler to use gson to obtain a map and construct your pojo from that map. Alternatively, if you don't like the map, create a pojo that looks like your JSON and map that pojo to the pojo you want.
Background/Reasoning: GSON is the mapper of your choice right now, but might be changed to something else, eg. Jackson, and all of your custom, framework specific mappers will need to be converted/changed if that happens. Using gson to create an object, that looks like the source, and map that to your custom POJO in your controller will make your codes intention clear and your code more resilient to framework changes.
I have been looking solution for this problem but could not find one so asking this question.
I have some data which looks like this
{
"data": [
{
"id": "5ab892c71810e201e81b9d39",
"isSignedUpUsingFb": false,
"personalInformation": {
"firstName": "jio",
"lastName": "g",
"mobileNumber": "1234567890",
},
"accountBalance": 0,
}
]
},
I want to write a java code to change the data structure to this
{
"data": [
{
"id": "5ab892c71810e201e81b9d39",
"isSignedUpUsingFb": false,
"personalInformation_firstName":"jio",
"personalInformation_lastNAme":"g",
"personalInformation_mobileNumber":"1234567890",
"accountBalance": 0,
}
]
},
I am getting data from db as:
#Override
public List<User> getAllUsers() {
logger.debug("entering all users method");
List<User> allUsers=mongoOperations.findAll(User.class);
for (User user : allUsers) {
PersonalInformation info=user.getPersonalInformation());
//manipulation code here
user.setPersonalInformation(info);
}
return allUsers;
}
So I want to write a logic so that i can convert the data in desired format and send it a return type. I know how to do same thing using J query but I want to do it in backend so any code for the above or any link will help.
I have fond one solution which is very simple.So, basically when we create object for nested data we create it like this in JAVA.
public MyClass{
public String name;
public String contact;
public PersonalInformation personalinformation;
//setters and getter here
}
this will give me data as
"MyClass":{
"name": "abc",
"contact": "12345",
"personalInformation":{
"address": "asdasdasdad",
"city":"asdadad",
"pin": "asdfg",
}
}
so to remove this nested data we need to use #JsonUnwrapped which removes all the nested object and add it to our main object.
public MyClass{
public String name;
public String contact;
#JsonUnwrapped
public PersonalInformation personalinformation;
//setters and getter here
}
which will change the data structure as:
"MyClass":{
"name": "abc",
"contact": "12345",
"address": "asdasdasdad",
"city":"asdadad",
"pin": "asdfg",
}
for more reference you can check this link http://fasterxml.github.io/jackson-annotations/javadoc/2.0.0/com/fasterxml/jackson/annotation/JsonUnwrapped.html
Hope this helps.
There are multiple possible solutions. As Prabhav has mentioned the most intuitive one would be to create a new class and from there a object which can be transformed with a library to a JSON.
Variant one:
The new class would look like your data structure you want and access would be:
PersonalInformationJson pf = new PersonalInformationJson();
pf.setFirstName = info.getPersonalInformation_firstName
//... setting the rest of the object
//using jackson
ObjectMapper mapper = new ObjectMapper();
try {
// convert user object to json string and return it
String jsonString = mapper.writeValueAsString(u);
}
The other easier version to create a string, either per hand or use a lib:
// using org.json.JSONObject
String jsonString = new JSONObject().put("personalInformation_firstName", info.value())
.put("personalInformation_lastNAme", info.value());
I'm having trouble mapping the environments array in the below JSON response output into a list of Environment objects using RestTemplate.
The name property of ApplicationData is being populated with Deploy app which is correct. However, the list of environments in Application Data is null. I'd like it to be populated with the corresponding id's and names from the output.
JSON output
{
"id": 4587521,
"oid": 8738390651982315522,
"name": "Deploy app",
"description": "",
"environments": [
{
"id": 4751361,
"name": "Stage",
"position": 0,
"configurationState": "TASKED"
},
{
"id": 4751362,
"name": "Dev",
"position": 1,
"configurationState": "TASKED"
},
]
}
ApplicationData.java
#JsonIgnoreProperties(ignoreUnknown = true)
public class ApplicationData {
private String name;
private List<Environment> environments;
// Getters and setters omitted
}
Environment.java
public class Environment {
private String id;
private String name;
// Getters and setters omitted
}
RestTemplate code
List<ApplicationData> applications = new ArrayList<>();
ResponseEntity<List<ApplicationData>> response =
restTemplate.exchange("/deploy/project/all", HttpMethod.GET, null,
new ParameterizedTypeReference<List<ApplicationData>>() {});
applications = response.getBody();
I ended up modifying my ApplicationData class so the property was an array of Environment objects:
private Environment[] environments;
It then populated correctly.
But what I do not get is, you serialize to List<ApplicationData> but your JSON output snippet shows only a single ApplicationData object, not a list with this single object. Did you apply any Jackson Deserialization Features like ACCEPT_SINGLE_VALUE_AS_ARRAY?