How to create an empty JsonNode?

Question

I am trying to set an empty node as a value of some other json node. new JsonNode() didn't work as that is protected.

Example:

JsonNode jsonNode = externalSource(); // <--This is the parent json node
((ObjectNode) jsonNode).set("fieldName", new JsonNode()); // <-- I want to replace the existing 
// value of fieldName with an empty one

This will not work currently.

Any particular way we can do this?

Hello, have you tried this so far? ObjectNode node = mapper.createObjectNode(); Also what do you mean it didn't work? — Jameu Lukasli1
– Jameu Lukasli1, Commented Nov 1, 2022 at 6:43
The constructor is not public, it's protected. So a client can not use that directly to instantiate JsonNode. It can only be used by subclasses extending the JsonNode class. — Mooncrater
– Mooncrater, Commented Nov 1, 2022 at 6:46
To avoid misunderstandings, you have an already existing jsonnode and you want to add to it a new field like "empty": {}? — dariosicily
– dariosicily, Commented Nov 1, 2022 at 7:54
I think I found the solution. Can use object mapper's getNodeFactory and then textNode(...) etc to create JsonNodes — Mooncrater
– Mooncrater, Commented Nov 1, 2022 at 8:59

sanurah · Accepted Answer · 2022-11-01 13:02:17Z

19

ObjectMapper mapper = new ObjectMapper();
JsonNode node = mapper.createObjectNode();

or you can also do like you said in the comment above,

JsonNode node = JsonNodeFactory.instance.objectNode();

after that you can map the values,

JsonNode node = mapper.valueToTree(fromValue);

answered Nov 1, 2022 at 13:02

sanurah

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