Jackson @JsonProperty("SoMeVaLuE") to ignore case

Question

What I am trying to achieve:

Parse a json using Jackson and JsonProperty, however, the key, while always the same, comes in all flavor of upper lower cases.

What I tried:

The input json has a field {"field": "value"}

Therefore, in my POJO, I do this:

public record MyPojo(@JsonProperty("field") String field

This works, but then, the key comes in different flavor of cases.

i.e. {"fieLd": "value"} {"Field": "value"} {"fIEld": "value"} etc

For now, I use the @JsonAlias("fieLd") etc...

But this is not scalable, since there are many permutations of cases.

Question:

How to tell Jackson and the JsonProperty to simply ignore the case?

Does this answer your question? [Case insensitive JSON to POJO mapping without changing the POJO](https://stackoverflow.com/questions/26058854/case-insensitive-json-to-pojo-mapping-without-changing-the-pojo) — Chaosfire, May 18 '23 at 09:27

score 2 · Accepted Answer · answered May 18 '23 at 09:33

i suggest putting the json to some kind of pre-processing-step to normalize property Names before Jackons does its json to object mapping

public class CustomDeserializer extends JsonDeserializer<MyObject> {
   @Override
   public MyObject deserialize(JsonParser jsonParser, DeserializationContext context) throws IOException {
       ObjectCodec codec = jsonParser.getCodec();
       JsonNode node = codec.readTree(jsonParser);
       ObjectNode normalizedNode = JsonNodeFactory.instance.objectNode();

       // Normalize property names
       Iterator<String> fieldNames = node.fieldNames();
       while (fieldNames.hasNext()) {
           String originalPropertyName = fieldNames.next();
           String normalizedPropertyName = normalizePropertyName(originalPropertyName);
           normalizedNode.set(normalizedPropertyName, node.get(originalPropertyName));
       }

       ObjectMapper mapper = (ObjectMapper) codec;
       JsonParser modifiedJsonParser = mapper.treeAsTokens(normalizedNode);
       return mapper.readValue(modifiedJsonParser, MyObject.class);
   }

   private String normalizePropertyName(String propertyName) {
       // Perform your normalization logic here
       // For example, convert to lowercase or replace spaces with underscores
       return propertyName.toLowerCase().replaceAll(" ", "_");
   }
}

and then wire up the deserializer as you see fit, for example by annotating the target Class

@JsonDeserialize(using = CustomDeserializer.class)
public class MyObject {
    // ...
}

Jackson @JsonProperty("SoMeVaLuE") to ignore case

1 Answers1