Is the Optional extractor no longer compatible with Common extractors?

[baby195lxl]

Summary

I previously wrote the following code according to the documentation of version 0.7.9

use axum::{
    extract::{Path, Query},
    routing::get,
    Router,
};
use uuid::Uuid;
use serde::Deserialize;

let app = Router::new().route("/users/:id/things", get(get_user_things));

#[derive(Deserialize)]
struct Pagination {
    page: usize,
    per_page: usize,
}

impl Default for Pagination {
    fn default() -> Self {
        Self { page: 1, per_page: 30 }
    }
}

async fn get_user_things(
    Path(user_id): Path<Uuid>,
    pagination: Option<Query<Pagination>>,
) {
    let Query(pagination) = pagination.unwrap_or_default();

    // ...
}

However, I found that this syntax seems to no longer be supported in version 0.8. How should I write the code to achieve the functionality of the above code?

axum version

0.8.1

[Turbo87]

#[derive(Deserialize)]
struct Pagination {
    #[serde(default = "1")]
    page: usize,
    #[serde(default = "30")]
    per_page: usize,
}

async fn get_user_things(
    Path(user_id): Path<Uuid>,
    Query(pagination): Query<Pagination>,
) {
    // ...
}

something like this is roughly what you want. alternatively, you can use Option<usize> inside the struct and remove the #[serde(default)] annotations.

[Turbo87]

see also #3135 (reply in thread)

[jplatte]

Small correction: serde(default = "...") must be given a function name, like:

#[derive(Deserialize)]
struct Pagination {
    #[serde(default = "default_page")]
    page: usize,
    #[serde(default = "default_page_size")]
    per_page: usize,
}

fn default_page() -> usize { 1 }
fn default_page_size() -> usize { 30 }