Jackson ObjectMapper - specify serialization order of object properties

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I'm implementing a RESTful web service where user has to send a signed verification token along with the request so that I could ensure that the request has not been tampered by a middle man. My current implementation is as follows.

Verification token is a VerifData object serialized into a String and then hashed and encrypted.

class VerifData {
    int prop1;
    int prop2;
}

In my service, I put data to be serialized into an instance of VerifData and then serialize it using Jackson ObjectMapper and passed along to the verification engine along with the verification token.

VerfiData verifData = new VerifData(12345, 67890);
ObjectMapper mapper = new ObjectMapper();
String verifCodeGenerated = mapper.writeValueAsString(verifData);

But it seems that each time the application container is started, the order of properties being mapped into a string by ObjectMapper changes.

Ex: one time it would be

{"prop1":12345,"prop2":67890}

and another time it would be

{"prop2":67890,"prop1":12345}

So if client has serialized the VerifData instance as into the first String, there is 50% chance of it being failed even though it is correct.

Is there a way to get around this? Can I specify the order of properties to map by ObjectMapper (like in ascending order)? Or is there any other way to best implement this verification step. Both client and server implementations are developed by me. I use Java Security API for signing and verifying.

From the Jackson Annotations documentation:

// ensure that "id" and "name" are output before other properties
@JsonPropertyOrder({ "id", "name" })

// order any properties that don't have explicit setting using alphabetic order
@JsonPropertyOrder(alphabetic=true)

How to serialize the order of properties using the Jackson library in , It takes as property a list of fields that defines the order in which fields can appear in the string resulting from the object JSON serialization. Jackson library provides a @JsonPropertyOrder annotation to specify the order of properties on serialization. Dependencies Let’s first add the following dependencies to the pom.xml:

The annotations are useful, but can be a pain to apply everywhere. You can configure your whole ObjectMapper to work this way with

Current Jackson versions: objectMapper.configure(MapperFeature.SORT_PROPERTIES_ALPHABETICALLY, true)

Older Jackson versions: objectMapper.configure(SerializationConfig.Feature.SORT_PROPERTIES_ALPHABETICALLY, true);

Jackson JSON: using @JsonPropertyOrder annotation to define , It takes as property a list of fields that defines the order in which fields will appear in the string resulting from the object JSON serialization. The Jackson ObjectMapper class (com.fasterxml.jackson.databind.ObjectMapper) is the simplest way to parse JSON with Jackson.The Jackson ObjectMapper can parse JSON from a string, stream or file, and create a Java object or object graph representing the parsed JSON.

In Spring Boot you can add this behaviour globally by adding the following to your Application entry point class:

  @Bean
  public Jackson2ObjectMapperBuilder objectMapperBuilder() {

    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    builder.featuresToEnable(MapperFeature.SORT_PROPERTIES_ALPHABETICALLY);

    return builder;
  }

Jackson JSON, @JsonPropertyOrder annotation is used to specify the ordering of the serialized properties. Example. POJO. @JsonPropertyOrder({"name"� Jackson ObjectMapper-specify serialization order of object properties (5) From Duncan McGregor's answer: Its better to use it like this: objectMapper. configure (SerializationConfig. Feature. SORT_PROPERTIES_ALPHABETICALLY, true);

There is an easier way in Spring Boot by specifying a property (in application.properties for example:

spring.jackson.mapper.sort_properties_alphabetically=true

Creating a somewhat deterministic Jackson ObjectMapper, JSON serialization is not required to be deterministic. Since you already sorted the keys, you decide to just sort the values of all collections! You find the suspect code Set<Object> troll which has a JSON value of "troll": [1,� ObjectMapper provides functionality for reading and writing JSON, either to and from basic POJOs (Plain Old Java Objects), or to and from a general-purpose JSON Tree Model (JsonNode), as well as related functionality for performing conversions.

In Jackson 2.x, which you are probably using today, use:

ObjectMapper mapper = new ObjectMapper();
mapper.configure(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS, true);

If you care about looks, you may also consider SerializationFeature.INDENT_OUTPUT as well.

Note that you must serialize Maps or Objects for this to sort correctly. If you serialize a JsonNode for example (from readTree), that won't be properly indented.

Example
import com.fasterxml.jackson.databind.*;

ObjectMapper mapper = new ObjectMapper();
mapper.configure(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS, true);
mapper.configure(SerializationFeature.INDENT_OUTPUT, true);

String input = "{\"hello\": {\"cruel\" : \"world\"} }";
Object pojo = mapper.readValue(input, Object.class);
System.out.println(mapper.writeValueAsString(pojo));

results in:

{
  "hello" : {
    "cruel" : "world"
  }
}

Jackson ObjectMapper – specify serialization order of object , Jackson ObjectMapper – specify serialization order of object order any properties that don't have explicit setting using alphabetic order. This tutorial will show how to ignore certain fields when serializing an object to JSON using Jackson 2.x. This is very useful when the Jackson defaults aren't enough and we need to control exactly what gets serialized to JSON – and there are several ways to ignore properties.

Jackson 2.3.0 default serialization order, In 2.3.0, when serializing a Java class's attributes to JSON, it appears that all annotation is for when I want to specify my own custom order. Object Id and Type Id preceding other properties), there is no defined ordering. Jackson JSON: using @JsonPropertyOrder annotation to define properties serialization order Posted on October 24, 2016 by Davis Molinari In the comments to a previous article a blog reader asked support for how to customize the order in which the properties of an object appear in the string resulting from its JSON serialization, using the

java Jackson ObjectMapper specify serialization order of object , java Jackson ObjectMapper specify serialization order of object properties? spring.jackson.mapper.sort_properties_alphabetically=true. There is an easier way� The simple readValue API of the ObjectMapper is a good entry point. We can use it to parse or deserialize JSON content into a Java object. Also, on the writing side of things, we can use the writeValue API to serialize any Java object as JSON output.

JSON Properties Order Change (Jackson), use to define the order of JSON properties while serialization from Java to JSON. Complete ExampleCode to convert Java object to JSON. That kind of global configuration can be done at the ObjectMapper level, by turning on the AutoDetect function to use either public fields or getter/setter methods for serialization, or maybe turn on serialization for all fields: ObjectMapper mapper = new ObjectMapper(); mapper.setVisibility(PropertyAccessor.ALL, Visibility.NONE); mapper

Comments
  • from the link "all codehaus services have been terminated"
  • As mentioned below, if your goal is to apply the ordering everywhere rather than when serializing a specific object, see stackoverflow.com/a/46267506/2089674.
  • This is not quite correct (or at least doesn't work in all scenarios) -- see stackoverflow.com/a/46267506/2089674 for a complete example of something that works.
  • @user2089674 - your example only works for Map keys. The OP requested a solution for Object fields.
  • There is only one map entry. I therefore cannot see it's order.