I am trying to learn rust with axum and planning to write a web server

Below is my server code

#[tokio::main]
async fn main() {
    dotenv().ok();

    // Establish database connection
    let db: DatabaseConnection = db::establish_connection().await;
    let db = Arc::new(db);

    // Build our application with a route
    let app = Router::new()
        .route("/admin/:adminname", get(get_admin))
        .route("/user", post(create_user))
        .layer(Extension(db.clone()));
        

    // Run our app with hyper
    let listener = tokio::net::TcpListener::bind("0.0.0.0:3000").await.unwrap();
    axum::serve(listener, app)
        .await
        .unwrap();
}

and my handler

#[derive(Deserialize)]
pub struct CreateUserRequest {
    pub username: String,
    pub password: String,
    pub name: String,
    pub age: i32,
    pub gender: String,
    pub birthday: String,
    pub email: String,
    pub phone: String,
    pub address: String,
    pub department_id: i32,
    pub hire_date: String,
}

pub async fn create_user(
    Json(payload): Json<CreateUserRequest>,
    Extension(db): Extension<Arc<DatabaseConnection>>,
) -> impl IntoResponse {
    let new_user = user_info::ActiveModel {
        username: Set(payload.username),
        password: Set(payload.password),
        name: Set(payload.name),
        age: Set(payload.age),
        gender: Set(payload.gender),
        birthday: Set(payload.birthday.parse().unwrap()), // Ensure proper parsing of date
        email: Set(payload.email),
        phone: Set(payload.phone),
        address: Set(payload.address),
        department_id: Set(payload.department_id),
        hire_date: Set(payload.hire_date.parse().unwrap()), // Ensure proper parsing of date
        ..Default::default() // Remaining fields can be defaulted
    };

    match new_user.insert(&*db).await {
        Ok(_) => StatusCode::CREATED,
        
        Err(_) => StatusCode::INTERNAL_SERVER_ERROR
    }
    
}

However, I encountered the following problem:

error[E0277]: the trait bound `fn(axum::Json<software_final::handler::CreateUserRequest>, axum::Extension<std::sync::Arc<sea_orm::DatabaseConnection>>) -> impl std::future::Future<Output = impl axum::response::IntoResponse> {software_final::handler::create_user}: axum::handler::Handler<_, _>` is not satisfied
   --> srcmain.rs:21:30
    |
21  |         .route("/user", post(create_user))
    |                         ---- ^^^^^^^^^^^ the trait `axum::handler::Handler<_, _>` is not implemented for fn item `fn(Json<CreateUserRequest>, Extension<Arc<DatabaseConnection>>) -> impl Future<Output = ...> {create_user}`
    |                         |
    |                         required by a bound introduced by this call
    |
    = help: the following other types implement trait `axum::handler::Handler<T, S>`:
              <axum::handler::Layered<L, H, T, S> as axum::handler::Handler<T, S>>
              <axum::routing::MethodRouter<S> as axum::handler::Handler<(), S>>
note: required by a bound in `axum::routing::post`
   --> .cargoregistrysrcmirrors.ustc.edu.cn-61ef6e0cd06fb9b8axum-0.7.5srcroutingmethod_routing.rs:389:1
    |
389 | top_level_handler_fn!(post, POST);
    | ^^^^^^^^^^^^^^^^^^^^^^----^^^^^^^
    | |                     |
    | |                     required by a bound in this function
    | required by this bound in `post`
    = note: this error originates in the macro `top_level_handler_fn` (in Nightly builds, run with -Z macro-backtrace for more info)

the dependencies are

sea-orm = { version = "0.12", features = [ "sqlx-mysql", "runtime-tokio-rustls", "macros" ] }
axum = "0.7.5"
tokio = { version = "1.29.1", features = ["full"] }
tower = "0.4.13"
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0"
dotenv = "0.15"

it’s my first time using axum and i don’t really understand the info that compiler says

really want to know how to fix it and the reason why i got this problem