json-shapeshifter

An incremental Json-to-Json transformation library written in Java.

It provides a step-by-step API to specify a transformation from a source schema to a target schema, both defined using Json Schema. The resulting transformation can be applied on Json instances of the source schema, to produce instances of the target schema. Got it?

Although it does transform Json to Json, its primary focus is on the process of specifying this transformation. If you are looking for a pure Json-to-Json transformation tool in Java (or compatible), have a look at JQ, JOLT or JsonIQ which are probably faster and more approriate.

TL;DR --> Code

Schema source = Schema.buildSchema("source.json");
Schema target = Schema.buildSchema("target.json");

Transformation t = new Transformation (source, target);

// iterate through all target nodes needing a binding
Iterator<SchemaNode> it = t.toBind();
while (it.hasNext()) {

	SchemaNode targetNode = it.next();

	// fetch all possible source nodes for this node
	Set<SchemaNode> sources = t.legalNodesFor(targetNode);

	// show this list to your user and let her choose amongst the
	// various Binding options (constant, node, handlebars, etc.) This
	// is where the value is: make this transformation process interactive,
	// let your user decide how to transform, at runtime!
	Binding b = new StringNodeBinding(source.at("/some/string/field"));

	// use the selected binding for the target node
	t.bind(targetNode, b);
}

// load a Json instance of the source schema (using Jackson here)
ObjectMapper om = new ObjectMapper();
JsonNode payload = om.readTree(new File("payload.json"));
if (!source.validate(payload).isSuccess()) {
	...
}

// transform it
JsonNode result = t.apply(payload);
target.validate(result).isSuccess(); // returns true, yeah baby!

// display it (using Jackson again)
String s = om.writerWithDefaultPrettyPrinter().writeValueAsString(result)
System.out.println(s);

Try it

Get it from Maven Central

That's the easiest. Current version is 0.1.1 (it's a beta but it does things)

<dependency>
   <groupId>la.alsocan</groupId>
   <artifactId>json-shapeshifter</artifactId>
   <version>0.1.1</version>
</dependency>

Build from the source

• Checkout out the sources
• Open the project in Netbeans (yeah, that's the easiest for now)
• In the Projects view, right-click on project and Custom --> Do the damn thing
• The project shall be built and the artifact installed in your local repository
• For convenience, a Main class is executed

Credits

This project uses Jackson massively, a bit of json-schema-validator and Handlebars for one particularly useful binding class. Of course Maven and JUnit / Hamcrest are there to support the build and tests.

License

Under MIT License.