柴油取单亲和许多孩子-火箭

Question

我已经能够让所有的父母和所有的孩子在一起 有谁知道如何让所有子女都成为单亲父母？

pub struct CityAndNeighbourhoods(CustomerCity, Vec<Vec<CustomerNeighbourhood>>);

pub fn get_customer_city_with_neighbourhoods(
    id: i64,
    connection: &PgConnection,
) -> QueryResult<CityAndNeighbourhoods> {
    // Load a single customer_citys given an id
    let city = customer_citys::table
        .find(id)
        .first::<CustomerCity>(&*connection)
        .expect("Error loading city");
    // Load all customer_neighbourhoods belong to the customer_citys above
    // and group by customer_citys
    let neighbourhoods =
        CustomerNeighbourhood::belonging_to(&city).load::<CustomerNeighbourhood>(connection)?;
    // Return all customer_citys with them customer_neighbourhoods
    let data = CityAndNeighbourhoods(city, neighbourhoods.into_iter().zip().collect::<Vec<_>>());
    Ok(data)
}

Answer 1

创建一个元组；

pub fn get_customer_city_with_neighbourhoods(
    id: i64,
    connection: &PgConnection,
) -> QueryResult<(CustomerCity, Vec<CustomerNeighbourhood>)> {
    // Load a single customer_citys given an id
    let city = customer_citys::table
        .find(id)
        .first::<CustomerCity>(&*connection)
        .expect("Error loading city");
    // Load all customer_neighbourhoods belong to the customer_citys above
    // and group by customer_citys
    let neighbourhoods =
        CustomerNeighbourhood::belonging_to(&city).load::<CustomerNeighbourhood>(connection)?;
    // Return all customer_citys with them customer_neighbourhoods
    Ok((city, neighbourhoods))
}