Gin Suggestion regarding parsing input

Description

There's a use-case where I would like to exactly know if a key is present in the body of POST/PATCH. I would like know if a field in body is actually being sent as null or it has been not sent at all. What is the best way to do this in gin framework?

What I am doing as of now?

Have written a custom body parser

func BodyParsing[T any](request *http.Request) (T, []string, error) {
    jsonData, _ := ioutil.ReadAll(request.Body)
    mapBody := make(map[string]interface{})
    var body T
    err := json.Unmarshal(jsonData, &body)
    if err != nil {
        return body, []string{}, err
    }
    validateErr := binding.Validator.ValidateStruct(body)
    if validateErr != nil {
        return body, []string{}, validateErr
    }
    err2 := json.Unmarshal(jsonData, &mapBody)
    if err2 != nil {
        return body, []string{}, err2
    }
    keys := make([]string, 0, len(mapBody))
    for k := range mapBody {
        keys = append(keys, k)
    }
    return body, keys, nil
}

Environment

• go version: 1.18
• operating system: Ubuntu 22.04