I tried to get last insert rowid from SQLite via Diesel. #rust

last_insert_rowid.rs

#[macro_use]
extern crate diesel;

pub mod models;
pub mod schema;

use diesel::prelude::*;
use diesel::sqlite::SqliteConnection;

use self::models::{Post, NewPost};

pub fn create_post<'a>(conn: &SqliteConnection, title: &'a str, body: &'a str) -> usize {
    use schema::posts;

    let new_post = NewPost {
        title: title,
        body: body,
    };

    diesel::insert_into(posts::table)
        .values(&new_post)
        .execute(conn)
        .expect("Cannot insert")
}

pub fn establish_connection() -> SqliteConnection {
    let database_url = "tutu.db";
    SqliteConnection::establish(&database_url).expect("Can't connect DB")
}  

no_arg_sql_function!(last_insert_rowid, diesel::sql_types::Bigint);

fn main() {
    let connection = establish_connection();
    create_post(&connection, "title", "body");
    let x: i64 = diesel::select(last_insert_rowid).first(&connection).unwrap();
}