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mod employee {
    #[derive(Debug, elephantry::Entity)]
    #[elephantry(model = "Model", structure = "Structure", relation = "employee")]
    pub struct Entity {
        #[elephantry(pk)]
        pub employee_id: i32,
        pub first_name: String,
        pub last_name: String,
        pub birth_date: chrono::NaiveDate,
        pub is_manager: bool,
        pub day_salary: bigdecimal::BigDecimal,
        #[elephantry(virtual)]
        pub departments: Vec<crate::department::Entity>,
    }

    impl Model {
        pub fn employee_with_department(&self, id: i32) -> elephantry::Result<Entity> {
            use elephantry::{Model, Projectable};

            let employee_projection = Self::create_projection()
                .unset_field("department_id")
                .add_field("departments", "array_agg(depts)")
                .alias("e")
                .to_string();

            let employee = <Self as elephantry::Model>::Structure::relation();

            let department_projection = super::department::Model::create_projection()
                .alias("d")
                .unset_field("parent")
                .to_string();

            let department = super::department::Structure::relation();

            let sql = format!(
                r#"
with recursive
    depts (department_id, name, parent_id) as (
        select {department_projection} from {department} d join {employee} e using(department_id) where e.employee_id = $1
        union all
        select {department_projection} from depts parent join {department} d on parent.parent_id = d.department_id
    )
select {employee_projection}
    from {employee} e, depts
    where e.employee_id = $1
    group by e.employee_id
"#
            );

            Ok(self.connection.query::<Entity>(&sql, &[&id])?.get(0))
        }
    }
}

mod department {
    #[derive(Clone, Debug, elephantry::Entity, elephantry::Composite)]
    #[elephantry(model = "Model", structure = "Structure", relation = "department")]
    pub struct Entity {
        #[elephantry(pk)]
        department_id: i32,
        name: String,
        parent_id: Option<i32>,
    }
}

fn main() -> elephantry::Result {
    env_logger::init();

    let database_url =
        std::env::var("DATABASE_URL").unwrap_or_else(|_| "postgres://localhost".to_string());
    let elephantry = elephantry::Pool::new(&database_url)?;
    elephantry.execute(include_str!("structure.sql"))?;

    let employee_with_department = elephantry
        .model::<employee::Model>()
        .employee_with_department(1)?;
    dbg!(employee_with_department);

    Ok(())
}