Json schema with anyOf field to java record

Question

How can I generate java record objects for java schemas with the anyOf field?

I have the following schemas:

animals.json

{
    "type": "object",
    "properties": {
        "animals": {
            "type": "array",
            "items": {
                "anyOf": [
                    {"$ref": "mammale.json"},
                    {"$ref": "bird.json"}
                ],
                "minContains": 1,
                "uniqueItems": true
            }
        }
    }
}

mammal.json

{
    "type": "object",
    "properties": {
        "mammalType": {"type": "string"},
        "furColor": {"type": "string"}
    }
}

bird.json

{
    "type": "string"
}

I want to output a json that looks like the following:

{
    "animals": [
        {
            "mammalType": "dog",
            "furColour": "brown"
        },
        "someBirdsName"
    ]
}

Is there a recommended way to represent the 'anyOf' structure in the java records (preferably with Jackson annotation)?

I found a solution when using POJOs, where they use an interface: Json schema with anyOf fields to POJO

This looks like a good solution but how do I us an arbitrary string that doesnt implements the interface?

Answer 1

To produce json like the following:

{
  "animals" : [ {
    "mammalType" : "dog",
    "furColour" : "brown"
  }, 
    "someString"
  ]
}

Which corresponds to schema like this:

{
    "type": "object",
    "properties": {
        "animals": {
            "type": "array",
            "items": {
                "anyOf": [
                    {"$ref": "mammale.json"},
                    {"type": "String"}
                ],
                "minContains": 1,
                "uniqueItems": true
            }
        }
    }
}

Then the following will do it:

public record ResponseServiceAlgolia(Object[] animals) {}

public record Mammal(String mammalType, String furColour) {}

public static void main(String[] args) throws JsonProcessingException {
    
    Mammal mammal = new Mammal("dog", "brown");
    
    Object[] animals = new Object[] {mammal, "someString"};
    ResponseServiceAlgolia responseServiceAlgolia = new ResponseServiceAlgolia(animals);
    
    ObjectMapper objectMapper = JsonMapper.builder().enable(SerializationFeature.INDENT_OUTPUT).build();
    
    var json = objectMapper.writeValueAsString(responseServiceAlgolia);
    System.out.println(json);

}

Output:

{
  "animals" : [ {
    "mammalType" : "dog",
    "furColour" : "brown"
  }, "someString" ]
}