Json, Jackson: polymorphism of one field, based on the value of other field

Question

Basically I'm trying to integrate with some other service that sends payloads with the following shape

{
  "storeId":"123",
  "type": "...",
  "data": ...,
  "createdAt": "...."
}

That shape never changes except for the property data, whose structure depends on the property type.

How can that be achieved with Jackson?

Answer 1

1. Use JsonNode to convert from string to json nodes JsonNode node = mapper.valueToTree(fromValue);
2. Then get your node using JsonNode dataNode = node.get("data"), same for type.
3. Get the class from the type node using Class yourBeanClass = Class.forName("package.+type from step 2");
4. Tokenize your data node using JsonParser parser = mapper.treeAsTokens(dataNode);
5. Finally get your bean instance by doing YourBean bean = mapper.readValue(parser, yourBeanClass);