java - Merging Two JSON Documents Using Jackson

Question

Is it possible to merge two JSON documents with the Jackson JSON library? I am basically using the Jackson mapper with simple Java Maps.

I've tried to search in Google and Jackson's documentation but couldn't find anything.

Answer 1

Inspired by StaxMans answer I implemented this merging method.

public static JsonNode merge(JsonNode mainNode, JsonNode updateNode) {

    Iterator<String> fieldNames = updateNode.fieldNames();
    while (fieldNames.hasNext()) {

        String fieldName = fieldNames.next();
        JsonNode jsonNode = mainNode.get(fieldName);
        // if field exists and is an embedded object
        if (jsonNode != null && jsonNode.isObject()) {
            merge(jsonNode, updateNode.get(fieldName));
        }
        else {
            if (mainNode instanceof ObjectNode) {
                // Overwrite field
                JsonNode value = updateNode.get(fieldName);
                ((ObjectNode) mainNode).put(fieldName, value);
            }
        }

    }

    return mainNode;
}

Hope this helps someone.