Diesel and Rocket imports break as soon as I include a file

Question

I have the file "user.rs" that has the struct of a postgres database table. Whenever I try to include it in my main.rs file (A Rocket web project), all of the Diesel "stuff" can't resolve. Here is my user.js file:

use super::schema::users;

pub mod handler;
pub mod repository;
pub mod router;

#[derive(Queryable, AsChangeset, Serialize, Deserialize)]
#[table_name = "users"]
pub struct User {
    pub id: String,
    pub username: String,
    pub password: String,
}

#[derive(Insertable)]
#[table_name = "users"]
pub struct InsertableUser {
    username: String,
    password: String,
}

pub impl InsertableUser {
    pub fn from_user(user: User) -> InsertableUser {
        InsertableUser {
            username: user.username,
            password: user.password,
        }
    }
}

pub fn all(connection: &PgConnection) -> QueryResult<Vec<User>> {
    users::table.load::<User>(&*connection)
}

pub fn get(id: i32, connection: &PgConnection) -> QueryResult<User> {
    users::table.find(id).get_result::<User>(connection)
}

pub fn insert(user: User, connection: &PgConnection) -> QueryResult<User> {
    diesel::insert_into(users::table)
        .values(&InsertableUser::from_user(user))
        .get_result(connection)
}

pub fn update(id: i32, user: User, connection: &PgConnection) -> QueryResult<User> {
    diesel::update(users::table.find(id))
        .set(&user)
        .get_result(connection)
}

pub fn delete(id: i32, connection: &PgConnection) -> QueryResult<usize> {
    diesel::delete(users::table.find(id)).execute(connection)
}

And here is my main.rs:

#![feature(proc_macro_hygiene, decl_macro)]

#[macro_use]
extern crate rocket;

#[macro_use]
extern crate rocket_contrib;

use rocket_contrib::databases::diesel;

#[database("camera-server-db")]
struct CameraServerDbConn(diesel::PgConnection);

mod user;

#[get("/")]
fn index() -> &'static str {
    "Hello World!"
}

fn main() {
    rocket::ignite()
        .attach(CameraServerDbConn::fairing())
        .mount("/", routes![index])
        .launch();
}

If I remove mod user; from main.rs, no error show up. When I run cargo check, I get many "cannot find x in this scope". Here's an example:

error: cannot find derive macro `AsChangeset` in this scope
 --> src/user.rs:7:21
  |
7 | #[derive(Queryable, AsChangeset, Serialize, Deserialize)]
  |                     ^^^^^^^^^^^

I'm trying to follow this guide (which is admittedly quite out of date, but it was one of the only actual guides I could find).

Answer 1

As mentioned in the linked guide in the section "The last step", you need to import diesel correctly otherwise the compiler cannot resolve those traits/derives/functions. That means you need to change your main.rs file as following:

#![feature(proc_macro_hygiene, decl_macro)]

#[macro_use]
extern crate rocket;

#[macro_use]
extern crate rocket_contrib;

#[macro_use]
extern crate diesel;

use rocket_contrib::databases::diesel;

#[database("camera-server-db")]
struct CameraServerDbConn(diesel::PgConnection);

mod user;

#[get("/")]
fn index() -> &'static str {
    "Hello World!"
}

fn main() {
    rocket::ignite()
        .attach(CameraServerDbConn::fairing())
        .mount("/", routes![index])
        .launch();
}

(note the additional #[macro_use] extern crate diesel; in your extern crate section.)