Immutable Json library for java
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README.md

Immutable Json library for java

This project attempts to build and AST ( Abstract Syntactic Tree ) for Json and provide a useful way to work with that tree.

If you want to program in functional style in Java, you want your data types to be immutable and efficient.

Unfortunately there are no default immutable collections in Java, so we try to use Vavr where appropriate. Vavr only has tuples and functions up to arity 8. We have increased the tuple and function arity to 27. Have a look in the net.hamnaberg.json.util in the codec package.

Status

Maven Central Build Status Gitter Chat

Community

Adopters

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Related projects

Usage

A short example showing encoding/decoding of a few different types. Note the List type is from io.vavr.collection to have an immutable List type. Also note that the Tuples type is from net.hamnaberg.json.util to have Tuple constructors up to Tuple27

    static class Event {
        public final UUID ID;
        public final List<String> tags;
        public final String message;

        public Event(UUID ID, List<String> tags, String message) {
            this.ID = ID;
            this.tags = tags;
            this.message = message;
        }
    }

    @Test
    public void testEvent() throws Exception {
        String expected = "{"+
                      "\"id\":\"1e2f28ff-54b5-4ad4-9edb-36712dc52202\","+
                      "\"tags\":[\"travel\",\"code\"],"+
                      "\"message\":\"This is a test\""+
                   "}";

        // create a decoder for our Event
        DecodeJson<Event> decode = Decoders.decode(
                Decoders.DUUID.fieldDecoder("id"),
                FieldDecoder.TList("tags", Decoders.DString).withDefaultValue(List.empty()),
                FieldDecoder.TString("message"),
                Event::new
        );

        // create an encoder that will encode our Event into json
        EncodeJson<Event> encode = Encoders.encode(
                Encoders.EUUID.fieldEncoder("id"),
                FieldEncoder.EList("tags", Encoders.EString),
                FieldEncoder.EString("message")
        ).contramap(event -> Tuples.of(event.ID, event.tags, event.message));

        // a codec can both encode and decode a value
        JsonCodec<Event> codec = JsonCodec.lift(decode, encode);

        // parse raw json with help of jackson parser
        Json.JValue jValue = new JacksonStreamingParser().parse(expected);

        String json = codec
                .toJson(codec.fromJson(jValue).unsafeGet())
                .nospaces();

        assertThat(json).isEqualTo(expected);
    }

Where can we find this

Using maven, you download it from Maven Central using these coordinates:

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-ast</artifactId>
  <version>6.2.0</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-pointer</artifactId>
  <version>6.2.0</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-patch</artifactId>
  <version>6.2.0</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-jackson</artifactId>
  <version>6.2.0</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-native</artifactId>
  <version>6.2.0</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-javax</artifactId>
  <version>6.2.0</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-gson</artifactId>
  <version>6.2.0</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-codec</artifactId>
  <version>6.2.0</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-reflection-codec</artifactId>
  <version>6.2.0</version>
</dependency>

Snapshots can be found from Sonatype:

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-ast</artifactId>
  <version>6.3.0-SNAPSHOT</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-pointer</artifactId>
  <version>6.3.0-SNAPSHOT</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-jackson</artifactId>
  <version>6.3.0-SNAPSHOT</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-native</artifactId>
  <version>6.3.0-SNAPSHOT</version>
 </dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-javax</artifactId>
  <version>6.3.0-SNAPSHOT</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-codec</artifactId>
  <version>6.3.0-SNAPSHOT</version>
</dependency>

<dependency>
  <groupId>net.hamnaberg.json</groupId>
  <artifactId>immutable-json-reflection-codec</artifactId>
  <version>6.3.0-SNAPSHOT</version>
</dependency>

License

We are using the Apache License 2.0

Contributing

All contributions are welcome! Documentation is sorely lacking and really needs some love. If you find a missing combinator, please open a PR or issue so we can discuss it. Any bugs or missing features are also welcome.