使用diesel时，是否可以在自定义约束中执行upsert

use diesel::prelude::*;
use diesel::pg::upsert::*;

table! {
    users {
        id -> Integer,
        name -> Text,
        age -> Integer,
    }
}

#[derive(Insertable)]
#[table_name = "users"]
struct NewUser {
    name: String,
    age: i32,
}

fn main() {
    use self::users::dsl::*;

    let connection = PgConnection::establish("postgres://user:password@localhost/database")
        .expect("Failed to connect to database");

    let new_user = NewUser {
        name: "John".to_string(),
        age: 25,
    };

    let insert = diesel::insert_into(users)
        .values(&new_user)
        .on_conflict(id)
        .do_update()
        .set((name.eq(excluded(name)), age.eq(excluded(age))));

    diesel::insert_into(users)
        .values(&new_user)
        .execute(&connection)
        .expect("Failed to insert user");

    let upserted_rows = insert
        .execute(&connection)
        .expect("Failed to upsert user");

    println!("Upserted rows: {}", upserted_rows);
}