Question 328874 in Json Question posted in
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How to retrieve specific JSON objects only from a nested JSON

I have a nested JSON structure. I want to retrieve only a particular branch of the structure and ignore rest of the objects in the json. I am not sure on the approach to achieve this. Please suggest.
For example:

{
"prop1":"val1",
"prop2":{
  "child":"childval"
},
"prop3":{
 "child":"childval"
}

}

Here, I want to retrieve only prop3 along with prop1 ignoring prop2.

{
"prop1":"val1",
"prop3":{
 "child":"childval"
}
}

Would it require the usage of jackson libraries?

Tags:

2

Answers


  1. 0

    If you’re using Jackson, it will deserialize only the stuff you define.
    Here is some code (that uses lombok for the getters and setters).
    First define classes that represent the JSON structure.

    @Getter
@Setter
public class Prop3
{
  private String child;
}

@Getter
@Setter
public class Blammy
{
  private String prop1;
  private Prop3 prop3;
}

    Here is code to deserialize the JSON from a String.

    Blammy blammy;
ObjectMapper mapper = new ObjectMapper();

blammy = mapper.readValue(jsonString, Blammy.class);
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  2. 0

    Any Java library for JSON (de)serialization should be able to handle this, but here is how you can achieve it using Jackson:

        // Required imports

    public static String removeProps(String json, List<String> propertiesToRemove) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        JsonNode rootNode = mapper.readTree(json);

        propertiesToRemove.forEach(prop -> removeProp(rootNode, prop));

        return rootNode.toString();
    }

    public static void removeProp(JsonNode node, String prop) {
        if (node.isObject()) {
            ObjectNode objectNode = (ObjectNode) node;
            if (objectNode.has(prop)) {
                objectNode.remove(prop);
            } else {
                objectNode.fields().forEachRemaining(entry -> removeProp(entry.getValue(), prop));
            }
        } else if (node.isArray()) {
            node.elements().forEachRemaining(element -> removeProp(element, prop));
        }
    }

    // Example usage
String json = "{"prop1":"val1","prop2":{"child":"childval"},"prop3":{"child":"childval"}}";

List<String> propsToRemove = List.of("prop2");
String jsonWithoutProps = removeProps(json, propsToRemove);
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