Jackson: generate schemas with references

Question

When using Jackson\'s JSON schema module, instead of serializing the complete graph I\'d like to stop whenever one of my model classes is encountered, and use the class nam

Answer 1

You can try and use following code -

    ObjectMapper MAPPER = new ObjectMapper();
    SchemaFactoryWrapper visitor = new SchemaFactoryWrapper();

    JsonSchemaGenerator generator = new JsonSchemaGenerator(MAPPER);

    JsonSchema jsonSchema = generator.generateSchema(MyBean.class);

    System.out.println(MAPPER.writeValueAsString(jsonSchema));

But your expected output is not valid, it won't say $ref, unless it has specified the schema for "Animals" at least once.

{
    "type": "object",
    "id": "urn:jsonschema:com:tibco:tea:agent:Zoo",
    "properties": {
        "animals": {
            "type": "array",
            "items": {
                "type": "object",
                "id": "urn:jsonschema:com:tibco:tea:agent:Animal",
                "properties": {
                    "species": {
                        "type": "string"
                    }
                }
            }
        },
        "name": {
            "type": "string"
        }
    }
}

Answer 2

Here's a custom SchemaFactoryWrapper that solves the problem. No guarantees, but it seems to work pretty well with Jackson 2.4.3.

UPDATE: With Jackson 2.5 onward it's a lot easier. Now you can specify a custom VisitorContext.

Answer 3

You can use the HyperSchemaFactoryWrapper instead of SchemaFactoryWrapper. In this way you will get urn reference for nested entities:

HyperSchemaFactoryWrapper visitor= new HyperSchemaFactoryWrapper();
ObjectMapper mapper = objectMapperFactory.getMapper();
mapper.acceptJsonFormatVisitor(mapper.constructType(Zoo.class), visitor);
JsonSchema jsonSchema = visitor.finalSchema();

System.out.println(mapper.writeValueAsString(jsonSchema));