Working with JSON

mangoo I/O uses boon JSON for parsing JSON. boon is a very fast JSON handler with its main focus on serializing and deserializing of objects.

JSON Input

To retrieve JSON which is send to your mangoo I/O application you have three options: automatic object serialization, generic object convertion or working with the raw JSON string.

Custom serializer

By default JSON Boon will not write out nulls, empty lists or values that are default values. If you want a value to be written out even if it is empty, null, false or 0, you can use the @JsonInclude annotation. If you want a value to be excluded from JSON generation you can use the @JsonIgnore annotation.

public class Car {
    @JsonInclude
    public String brand = null;

    @JsonInclude
    public int doors = 0;

    @JsonIgnore
    public String comment = "blablabla";

    public String foo = "blablabla";

    public Car() {}
}

You can customize the JSON serialization by overwriting the JsonSerializer in the JSONUtils class which is recommended to use, when working with JSON in mangoo I/O.

JsonSerializerFactory jsonSerializerFactory = new JsonSerializerFactory();
jsonSerializerFactory.useAnnotations();
jsonSerializerFactory.useFieldsOnly();
...
JsonSerializer serializer = jsonSerializerFactory.create();

JsonUtils.withJsonSerializer(serializer);

It is recommended that you customize the serializer when the framework starts using the lifecycle methods.

Automatic object convertion

Consider the Car class from above and the following JSON send to mangoo I/O

{
    "brand" : "Nissan",
    "doors" : 4
}

To handle this JSON with automatic object convertion you can simply do this in a controller.

package controllers;

import io.mangoo.routing.Response;
import models.Car;

public class JsonController {
    public Response parse(Car car) {
        // TODO Do something with person object
        ...
    }
}

You just pass the object you want to convert from the JSON request and mangoo I/O automatically makes the serialization to your POJO, making it available in your controller.

If you don’t have a POJO and you want to retrieve the JSON content, mangoo I/O offers you a generic way of retrieving the content through the object body of a request to a Map.

package controllers;

import io.mangoo.routing.Response;
import io.mangoo.routing.bindings.Request;

public class MyController {
    public Response parse(Request request) {
        Map myjson = request.getBodyAsJsonMap();
        String foo = json.get("firstname");
    }
}

You can also get hold of the JSON using the great JsonPath library.

package controllers;

import io.mangoo.routing.Response;
import io.mangoo.routing.bindings.Request;
import com.jayway.jsonpath.ReadContext;

public class MyController {
    public Response parse(Request request) {
        ReadContext readContext = request.getBodyAsJsonPath();
        String foo = readContext.read("$.firstname");
    }
}

Handle raw JSON string

If you don’t want mangoo I/O to automatically convert a JSON input you can also work with the raw JSON string. The body object contains the raw values of a request. Here is an example

package controllers;

import io.mangoo.routing.Response;
import io.mangoo.routing.bindings.Request;

public class MyController {
    public Response parse(Request request) {
        String body = request.getBody();
        ...
    }
}

JSON Output

Consider for example the following POJO.

package models;

public class Person {
    private String firstname;
    private String lastname;
    private int age;

    public Person(String firstname, String lastname, int age) {
        this.firstname = firstname;
        this.lastname = lastname;
        this.age = age;
    }

    public String getFirstname() {
        return firstname;
    }

   public String getLastname() {
       return lastname;
    }

    public int getAge() {
        return age;
    }
}

To create a new person object and send it as a response you can simply can do this in a controller

package controllers;

import io.mangoo.routing.Response;
import models.Person;

public class JsonController {
    public Response render() {
        Person person = new Person("Peter", "Parker", 24);
        return Response.withOk().andJsonBody(person);
    }
}

The output of the response will look as follows

{
    "firstname" : "Peter",
    "lastname" : "Parker",
    "age" : 24
}