Add a property to a json string with jackson json

Question

I am storing a json string into a text field in mysql. After the insertion, i want to update my json string and add the mysql line id into it with jackson json.

I have a java String which is in Json format

{
  "thing":"val"
}

I'm looking to add another K/V without writing lines of codes.

to finally have this :

{
  "thing":"val"
  "mysqlId":10
}

I can convert my String to a JsonNode :

ObjectMapper mapper = new ObjectMapper();
JsonNode json = mapper.readTree( jsonStr);

Looking to do something like this

json.put("mysqlId",10);
json.toString();

then update in my text field with new json string in mysql

I can't make it. I don't want use many class is there a simple way to do so with jackson?

Solution

Try casting your JsonNode to an com.fasterxml.jackson.databind.node.ObjectNode and then calling put set (or replace) on it.

Comments

[Jay Q.]

put method in ObjectNode is deprecated in v2.4. You need to use set or replace.

[Don Cheadle]

is there a way to leverage Jackson to just change the name of a property in a JSON string? I.e. suppose I want to change 'id' : 42 to 'my_id' : 42 - without having to know the value 42 and re-creating the property?