JAVA - Not converting CamelCase to Snake_Case using ObjectMapping and SetPropertyNamingStrategy - SNAKE_CASE

Question

i am trying to use PropertyNamingStrategy.SNAKE_CASE to convert a Map<String, Object> from CamelCase to Snake_Case - but without sucess. It is a "generic" MAP. Anyone can help me?

My class example:

   private ResponseEntity<Class> doPostRequest(Map<String, Object> payload) {
        
        ObjectMapper payloadConversor = new ObjectMapper();
        
        payloadConversor.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);      
        
        Map<String, Object> payloadConverted = payloadConversor
                .convertValue(payload, new TypeReference<Map<String, Object>>() {});  

} 

Thank you!

Answer 1

Renan. The example you showed isn't working because ObjectMapper does not consider a map key being a property. It only converts names of class fields. For example:

@Data
@AllArgsConstructor
public static class MyClass {
    private String myString;
}

System.out.println(objectMapper.writeValueAsString(new MyClass("asdfasdgADFAasdf")));

result: {"my_string":"asdfasdgADFAasdf"}

I could suggest that you take a look at a related question Converting a string from snake case to camel case in Java . Here you will find ways to convert strings to different case formats. Then you could just iterate through your map keys and convert them.

Hope you find this helpful!