Jackson JSON List with Object Type

Question

I have to serialize JSON from a list of Objects. The resulting JSON has to look like this:

{
    \"status\": \"success\",
    \"models\": [
        {
                


        

Answer 1

There's no built-in way to do this. You'll have to write your own JsonSerializer. Something like

class ModelSerializer extends JsonSerializer> {

    @Override
    public void serialize(List value, JsonGenerator jgen,
            SerializerProvider provider) throws IOException {
        jgen.writeStartArray();
        for (Model model : value) {
            jgen.writeStartObject();
            jgen.writeObjectField("model", model);
            jgen.writeEndObject();    
        }
        jgen.writeEndArray();
    }

}

and then annotate the models field so that it uses it

@JsonSerialize(using = ModelSerializer.class)
private List models;

This would serialize as

{
    "status": "success",
    "models": [
        {
            "model": {
                "id": 1,
                "color": "red"
            }
        },
        {
            "model": {
                "id": 2,
                "color": "green"
            }
        }
    ]
}

If you're both serializing and deserializing this, you'll need a custom deserializer as well.