Odd behavior when nesting root / path

[brownjohnf]

Bug Report

Version

v0.4.3

Platform

Linux 5.15.7-arch1-1 #1 SMP PREEMPT Wed, 08 Dec 2021 14:33:16 +0000 x86_64 GNU/Linux

Crates

axum, I believe

Description

While working on routes for an app, I wanted to add admin routes under /admin/.... I've got my routes in two modules, app and admin. I'm nesting them from the parent like so:

// main.rs
Router::new()
    .nest("/", app::routes())
    .nest("/admin", admin::routes())

and the app routes are:

// app.rs
Router::new()
    .route("/", get(foo::list))
    .route("/foo", get(foo::list).post(foo::create))

and the admin routes are:

// admin.rs
Router::new()
   .route("/", get(bar::list))
   .route("/bar", get(bar::list).post(bar::create))

I'd expect the above to produce the following route table:

GET / -> foo::list
GET /foo -> foo::list
POST /foo -> foo::create
GET /admin -> bar::list
GET /admin/bar -> bar::list
POST /admin/bar -> bar::create

What actually happens (based on my probing with curl) is the following:

GET / -> 404
GET //foo -> foo::list
POST //foo -> foo::create
(the rest is as expected)

I'm able to fix this by dropping the leading / from the nested app (foo) routes. I tried nesting them at "", but that won't compile. This isn't a blocker, now that I know this, but I found it extremely surprising. Is this the desired behavior?

[davidpdrsn]

Ah yeah I see there is a bug when doing .nest("/", a_router). I'll look into fixing that.

Note however that .nest("/", a_router) is the same as .merge(a_router) which does work and is probably clearer regardless.

[brownjohnf]

Many thanks! I appreciate the quick fix and guidance on .merge.