Crate joinable

joinable defines traits for joining iterables of values. Just as you can join two database tables in SQL to produce matching records from each, joinable provides you with simple functionality to achive the same in your Rust code.

The Joinable trait lets you join left- and right-hand sides, yielding (&L, &R) for inner joins and (&L, Option<&R>) for outer joins:

use joinable::Joinable;

let customers = get_customers();
let orders = get_orders();

let it = customers
    .iter()
    .outer_join(&orders[..], |c, o| c.id.cmp(&o.customer_id));

The JoinableGrouped trait joins left- and right-hand sides with right-hand side values collected into a Vec:

use joinable::JoinableGrouped;

let customers = get_customers();
let orders = get_orders();

let it = customers
    .into_iter()
    .outer_join_grouped(&orders[..], |c, o| c.id.cmp(&o.customer_id));

for (cust, ords) in it {
    if ords.is_empty() {
        println!("Customer '{}' has no orders", cust.name);
    } else {
        let total_spend = ords.iter().map(|o| o.amount_usd).sum::<f32>();
        println!("Customer '{}' has spent ${:0.2}", cust.name, total_spend);
    }
}

JoinableGrouped also exposes SEMIJOIN and ANTISEMIJOIN functionality, yielding only rows from the left-hand side where a match is or is not found, respectively, in the right-hand side:

use joinable::JoinableGrouped;

let customers = get_customers();
let orders = get_orders();

let customers_with_orders : Vec<&Customer> = customers
    .iter()
    .semi_join(&orders[..], |c, o| c.id.cmp(&o.customer_id))
    .collect();

let customers_without_orders : Vec<Customer> = customers
    .into_iter()
    .anti_join(&orders[..], |c, o| c.id.cmp(&o.customer_id))
    .collect();

Enums

RHS

A wrapper around the right-hand side of your join.

Traits

Joinable

A trait allowing the joining of a left-hand side (LHS) and a right-hand side (RHS) dataset. Results are yielded for pairs of values from LHS and RHS.

JoinableGrouped

A trait allowing the joining of a left-hand side (LHS) and a right-hand side (RHS) dataset.