[SOLVED] Rust optional nullable argument, unset or do nothing

Rust optional nullable argument, unset or do nothing

Let's say I have function that accept arguments to update a user like this:

pub struct User {
    pub user_id: Uuid,
    pub nickname: String,
    pub avatar: Option<String>,
}

pub struct UserUpdateProps {
    pub user_id: Uuid,
    pub nickname: Option<String>,
    pub avatar: Option<String>,
}

There is many props and operations like this. Update props are passed around, so you can't go with path call or not call an instance.

For nickname Option<String> works fine, it means if no nickname passed - no change required.

For avatar Option<String> doesn't work, because we can't handle two cases - unset and do nothing.

In javascript undefined would mean do nothing, null unset value.

What is the idiomatic way to handle this in rust?

Solution

Based on @Chayim Friedman suggestion, general usage enum seems the best way.

#[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
pub enum ValueOrNull<T> {
    Undefined,
    Null,
    Value(T),
}
impl<T> Default for ValueOrNull<T> {
    fn default() -> Self {
        Self::Undefined
    }
}