mathieuancelin / json-lib

JsonLib

Highly inspired and copied from @mandubian (Pascal Voitot) Json lib for Play 2 Scala

Will be the standard Json library for the ReactiveCouchbase Java wrapper

Import lib

using the JCenter repository

<dependency>
  <groupId>org.reactivecouchbase.json</groupId>
  <artifactId>json-lib</artifactId>
  <version>1.0.0</version>
</dependency>

compile 'org.reactivecouchbase.json:json-lib:1.0.0'

libraryDependencies += "org.reactivecouchbase.json" % "json-lib" % "1.0.0"

Json AST

Every json structure is represented with a Json AST.

In that AST, everything is a JsValue.

Then each json type inherit from it :

JsNumber, JsString, JsBoolean, JsObject, JsArray, JsUndefined, JsNull

The Json class provides the basic functions to create/manipulate json AST. Json also provides methods like Json.stringify, Json.prettyPrint and Json.parse to manipulate Json structures from and to strings.

The JsValue::as() method allows you to cast AST elements to specific JsValue subtypes or corresponding Java types.

You can also provide Reader and Writer to provide custom serialization/deserialization for you json ASTs. You can also use it to validate, transform or enhance json ASTs.

Create a Json Object

JsObject o = Json.obj(
    $( "key1", "value1" ),
    $( "key2", "value2" ),
    $( "key3", 1 ),
    $( "key4", 2.3 ),
    $( "key5", Json.obj(
        $( "key1", "value1" ),
        $( "key2", "value2" ),
        $( "key3", Json.arr(
            "val1", "val2", 3, Json.obj(
                $( "key1", "value1" )
            )
        ))
    ))
);

JsObject user = Json.toJson(new User(...));

Create Json string

JsObject o = Json.obj(
    $( "key1", "value1" ),
    $( "key2", "value2" )
);
String json = Json.stringify( o );  // {"key1":"value1", "key2":"value2"}

Create pretty Json string

String prettyJson = Json.prettyPrint( o );  // {
                                            //     "key1":"value1",
                                            //     "key2":"value2"
                                            // }

Create JsValue from string

JsValue jsVal = Json.parse( "{\"key1\":\"val1\"}" );
JsObject o = jsVal.as(JsObject.class);

Json object manipulation

JsObject jsObj = jsVal.as(JsObject.class);
for (JsObject obj : jsVal.asOpt(JsObject.class)) {
    JsObject newObj = obj.add(Json.obj( $( "key1", "value1" )));
    JsObject other = Json.obj(
        $( "key1", "value1" ),
        $( "key2", "value2" )
    );
    JsObject merged = newObj.merge(other);
    JsObject merged2 = newObj.deepMerge(other);
    String key1 = merged.field("key1").as(String.class);
}

for (String key1 : jsObj.field("key1").readOpt(String.class)) {
    System.out.println("the value of key1 is : " + key1);
}

Json array manipulation

Json.stringify(Json.arr("val1", "val2", "val3").append(Json.arr("val4", "val5")).add("val6")) // ["val1","val2","val3","val4","val5","val6"]
Json.arr("val1", "val2", "val3").append(Json.arr("val4", "val5")).add("val6").get(5) // val6

Custom Json reading and validating

import org.reactivecouchbase.json.*;
import static org.reactivecouchbase.json.Syntax.*;
import static org.reactivecouchbase.json.JsResult.*;
import static org.reactivecouchbase.json.DefaultReaders.*;
import static org.reactivecouchbase.json.ReaderConstraints.*;

Reader<User> userReader = new Reader<User>() {
     @Override
     public JsResult<User> read(JsValue value) {
         try {
             return new JsSuccess<User>(new User(
                 value.field("name").as(String.class),
                 value.field("surname").as(String.class),
                 value.field("age").as(Integer.class, validateWith(Integer.class, max( 99 ), min( 18 ))),
                 value.field("email").as(String.class, validateWith(String.class, matches( "^[_a-z0-9-]+(\\.[_a-z0-9-]+)*@[a-z0-9-]+(\\.[a-z0-9-]+)+$"))
             ));
         } catch (Exception e) {
             return new JsError<T>(new IllegalStateException("Ooops"));
         }
     }
};

or using functionnal composition of JsResults

// Java 8 lambda syntax for shorter examples
Reader<User> userReader = new Reader<User>() {
     @Override
     public JsResult<User> read(JsValue value) {
         return combine(
             value.field("name").read(String.class),
             value.field("surname").read(String.class),
             value.field("age").read( validateWith( Integer.class, max( 99 ), min( 18 ))),
             value.field("email").read( validateWith( String.class, matches( "^[_a-z0-9-]+(\\.[_a-z0-9-]+)*@[a-z0-9-]+(\\.[a-z0-9-]+)+$" ))
         ).map(tuple -> new User(tuple._1, tuple._2, tuple._3, tuple._4));
     }
};

JsResult<T> userResult = Json.fromJson(Json.parse(...), userReader);
for (User user : userResult) {
    System.out.println("Yeah user is : " + user.toString());
}

for (JsError<T> error : userResult.asError()) {
    System.err.println("Error while reading a user : " + error.firstError());
}

for (JsSuccess<T> success : userResult.asSucces()) {
    System.out.println("Yeah user is : " + success.get());
}

// Java 8 lambda syntax for shorter examples
userResult.filter(user -> user.age > 18).filterNot(user -> user.age < 99).map(user -> {
    System.out.println("Yeah user is : " + user.toString());
});

Custom Json writing

Writer<User> userWriter = new Writer<User>() {
    public JsValue write(User user) {
        return Json.obj(
            $("name", user.name),
            $("surname", user.surname),
            $("age", user.age),
            $("email", user.email),
            $("gravatar", String.format("http://www.gravatar.com/avatar/%s?s=50&d=wavatar", Codec.md5(user.email))
        );
    }
};

JsObject user = Json.toJson(new User(...), userWriter).as(JsObject.class);

Release

./gradlew release -PreleaseVersion=x.x.x