Function is_empty 

pub fn is_empty<T>(t: &T) -> bool
where
    T: IsEmpty,

Thin wrapper function around IsEmpty::is_empty. Use it with serde’s skip_serializing_if attribute.

use is_empty::IsEmpty;
use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize, IsEmpty)]
struct Foo {
    client_ip: Option<String>,
    client_country: Option<String>,
}

#[derive(Serialize, Deserialize)]
struct Root {
    #[serde(skip_serializing_if = "is_empty::is_empty")]
    foo: Foo,
}

let empty_foo = Foo { client_ip: None, client_country: None };
let root = Root { foo: empty_foo };
assert_eq!(serde_json::to_string(&root).unwrap(), "{}");