leon::Values trait compile issue

[flisky]

When I upgrade to leon v2.0.0, I cannot make the following code to compile:

#[repr(transparent)]
struct ObjectWrapper<'a>(&'a HashMap<&'a str, serde_json_borrow::Value<'a>>);

impl leon::Values for ObjectWrapper<'_> {
    fn get_value(&self, key: &str) -> Option<Cow<'_, str>> {
        let (top, keys) = match key.split_once('.') {
            Some((top, key)) => (top, key.split('.').collect()),
            None => (key, vec![]),
        };
        let mut val = self.0.get(top)?;
        for key in keys {
            val = key
                .parse::<usize>()
                .map_or_else(|_| val.get(key), |idx| val.get(idx));
        }
        match val {
            serde_json_borrow::Value::Null => None,
            serde_json_borrow::Value::Bool(v) => {
                Some(Cow::Borrowed(if *v { "true" } else { "false" }))
            }
            serde_json_borrow::Value::Number(v) => {
                Some(Cow::Owned(v.as_f64().unwrap().to_string()))
            }
            serde_json_borrow::Value::Str(v) => Some(Cow::Borrowed(v)),
            serde_json_borrow::Value::Array(_) => None,
            serde_json_borrow::Value::Object(_) => None,
        }
    }
}

the compile error:

32 |     fn get_value(&self, key: &str) -> Option<Cow<'_, str>> {
   |                  -           - let's call the lifetime of this reference `'1`
   |                  |
   |                  let's call the lifetime of this reference `'2`
...
51 |             serde_json_borrow::Value::Str(v) => Some(Cow::Borrowed(v)),
   |                                                 ^^^^^^^^^^^^^^^^^^^^^^ method was supposed to return data with lifetime `'2` but it is returning data with lifetime `'1`
   |

Could you please give me some hints, @NobodyXu Thanks!

[NobodyXu]

I think this is because of the serde_json_borrow::Index, it requires the key to outlive 'a, this thus somehow make the lifetime of the return value to be relates to the key since you use a subset of key to index the json-value.

Try manually look up the key in Value::object, I think this will solve your problem.

[flisky]

Thanks for the quick answer. Indeed, manually lookup does work.