Separated the code

src/callers/common.rs

@@ -0,0 +1,4 @@
+// basic handler that responds with a static string
+pub async fn root() -> &'static str {
+    "Hello, World!"
+}

src/callers/mod.rs

@@ -0,0 +1,7 @@
+pub mod common;
+pub mod register;
+
+pub mod endpoints {
+    pub const ROOT: &str = "/";
+    pub const REGISTER: &str = "api/v2/register";
+}

src/callers/register.rs

@@ -0,0 +1,12 @@
+use axum::{Json, http::StatusCode};
+
+use crate::models;
+
+pub async fn register_user(
+    Json(payload): Json<models::common::CreateUser>,
+) -> (StatusCode, Json<models::common::User>) {
+    let user = models::common::User {
+        username: payload.username.clone(),
+    };
+    (StatusCode::CREATED, Json(user))
+}