How to modify JsonNode in Java?

Question

I need to change a JSON attribute's value in Java, I can get the value properly but I couldn't modify the JSON.

here is the code below

  JsonNode blablas = mapper.readTree(parser).get("blablas");
    for (JsonNode jsonNode : blablas) {
        String elementId = jsonNode.get("element").asText();
        String value = jsonNode.get("value").asText();
        if (StringUtils.equalsIgnoreCase(elementId, "blabla")) {
            if(value != null && value.equals("YES")){
                 // I need to change the node to NO then save it into the JSON
            }
        }
    }

What is the best way to do this?

You could convert the JsonNode to a Java Map, e.g. `resultMap = mapper.convertValue(aJsonNode, Map.class);` modify it in the Map and then change that Map back to a JsonNode. Just saying. — MikeJRamsey56, Jul 25 '18 at 18:59

score 295 · Accepted Answer · edited Sep 20 '16 at 06:28

295

JsonNode is immutable and is intended for parse operation. However, it can be cast into ObjectNode (and ArrayNode) that allow mutations:

((ObjectNode)jsonNode).put("value", "NO");

For an array, you can use:

((ObjectNode)jsonNode).putArray("arrayName").add(object.ge‌tValue());

edited Sep 20 '16 at 06:28

Dave Jarvis

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answered Jun 23 '15 at 08:32

Sharon Ben Asher

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tried for a numeric type in which I need to change the value. I got this exception: `Exception in thread "main" java.lang.ClassCastException: com.fasterxml.jackson.databind.node.IntNode cannot be cast to com.fasterxml.jackson.databind.node.ObjectNode` – balboa_21 Nov 04 '17 at 14:39
You need to try "IntNode" – mulya Aug 09 '19 at 11:41
@balboa_21 changing an integer doesn't really make sense. It's a bit like me changing 4 to 9, then everyone in the world starts counting 1, 2, 3, 9, 5, 6, 7, 8. What you want to do is change the field on the object to contain a different integer, so you want to get the object higher up as an ObjectNode, and manipulate the relevant field. – MichaelRom Oct 22 '21 at 15:35
1

"ObjectNode.put()" is deprecated, can use "set" instead. – a3765910 Apr 08 '22 at 04:53
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error: "ObjectNode cannot be resolved to a type" – john k Apr 08 '22 at 21:02

score 13 · Answer 2 · answered Apr 03 '19 at 06:17

Adding an answer as some others have upvoted in the comments of the accepted answer they are getting this exception when attempting to cast to ObjectNode (myself included):

Exception in thread "main" java.lang.ClassCastException: 
com.fasterxml.jackson.databind.node.TextNode cannot be cast to com.fasterxml.jackson.databind.node.ObjectNode

The solution is to get the 'parent' node, and perform a put, effectively replacing the entire node, regardless of original node type.

If you need to "modify" the node using the existing value of the node:

get the value/array of the JsonNode
Perform your modification on that value/array
Proceed to call put on the parent.

Code, where the goal is to modify subfield, which is the child node of NodeA and Node1:

JsonNode nodeParent = someNode.get("NodeA")
                .get("Node1");

// Manually modify value of 'subfield', can only be done using the parent.
((ObjectNode) nodeParent).put('subfield', "my-new-value-here");

Credits:

I got this inspiration from here, thanks to wassgreen@

score 7 · Answer 3 · edited Nov 08 '16 at 19:52

7

I think you can just cast to ObjectNode and use put method. Like this

ObjectNode o = (ObjectNode) jsonNode; o.put("value", "NO");

edited Nov 08 '16 at 19:52

Alexander

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answered Jun 23 '15 at 08:33

Xdsasdf

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score 6 · Answer 4 · answered Nov 26 '18 at 13:12

6

The @Sharon-Ben-Asher answer is ok.

But in my case, for an array i have to use:

((ArrayNode) jsonNode).add("value");

answered Nov 26 '18 at 13:12

Alejandro

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score 2 · Answer 5 · edited May 23 '17 at 12:34

2

You need to get ObjectNode type object in order to set values. Take a look at this

edited May 23 '17 at 12:34

Community

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answered Jun 23 '15 at 08:31

Eugen Halca

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score 2 · Answer 6 · answered Apr 16 '18 at 00:35

Just for the sake of understanding of others who may not get the whole picture clear following code works for me to find a field and then update it

ObjectMapper mapper = new ObjectMapper();
JsonNode rootNode = mapper.readTree(JsonString);    
JsonPointer valueNodePointer = JsonPointer.compile("/GrandObj/Obj/field");
JsonPointer containerPointer = valueNodePointer.head();
JsonNode parentJsonNode = rootNode.at(containerPointer);

if (!parentJsonNode.isMissingNode() && parentJsonNode.isObject()) {
    ObjectNode parentObjectNode = (ObjectNode) parentJsonNode;
    //following will give you just the field name. 
    //e.g. if pointer is /grandObject/Object/field
    //JsonPoint.last() will give you /field 
    //remember to take out the / character 
    String fieldName = valueNodePointer.last().toString();
    fieldName = fieldName.replace(Character.toString(JsonPointer.SEPARATOR), StringUtils.EMPTY);
    JsonNode fieldValueNode = parentObjectNode.get(fieldName);

    if(fieldValueNode != null) {
        parentObjectNode.put(fieldName, "NewValue");
    }
}

score 0 · Answer 7 · answered Sep 19 '22 at 07:36

0

ObjectMapper mapper = new ObjectMapper();
Map<String, Object> nodeMap = mapper.convertValue(jsonNode, new TypeReference<Map<String, Object>>(){});
nodeMap.put("key", "value");
jsonNode = mapper.convertValue(nodeMap, JsonNode.class);

answered Sep 19 '22 at 07:36

Anurag Bhalekar

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How to modify JsonNode in Java?

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