View Formatting Helpers

Autumn's widget lane (card, data_table, property_list, hero, breadcrumb) renders containers. autumn_web::format renders the scalar values that go inside them — money, counts, and timestamps — so apps stop hand-rolling format!("${:.2}", price) and ad-hoc relative-time math in every template.

All helpers are pure functions that return HTML-escaped [maud::Markup], so they're safe to interpolate directly into html! { ... } blocks. They ship in the autumn_web::prelude (behind the default maud feature), so no extra imports are needed beyond the usual use autumn_web::prelude::*;.

Helpers at a glance

number_to_currency takes a rust_decimal::Decimal — the same exact-precision type used by decimal model fields — so money never rounds through a float on its way to the page.

Copy-paste example: money, count, and timestamp in a data_table

use autumn_web::prelude::*;
use autumn_web::widgets::{Column, DataTableConfig, data_table};

struct Order {
    id: i64,
    total: Decimal,
    item_count: i64,
    placed_at: chrono::DateTime<chrono::Utc>,
}

#[get("/orders")]
async fn index(clock: Clock, orders: Vec<Order>) -> Markup {
    let cols: Vec<Column<Order>> = vec![
        Column::new("Total", |row: &Order| html! { (number_to_currency(row.total)) }),
        Column::new("Items", |row: &Order| html! { (pluralize(row.item_count, "item")) }),
        Column::new("Placed", |row: &Order| {
            html! { (time_ago_in_words(row.placed_at, clock.now())) }
        }),
    ];

    html! {
        (data_table(&orders, &cols, &DataTableConfig::new("No orders yet.")))
    }
}

This renders each row's total as $1,234.50, item_count as 3 items (or 1 item), and placed_at as 2 hours ago — three helper calls, zero hand-written format!s.

Customizing currency output

number_to_currency uses [CurrencyOptions] defaults ($, 2 decimal places, ,/. separators). Build a [CurrencyOptions] directly for a different symbol, precision, or separators:

use autumn_web::prelude::*;

let opts = CurrencyOptions::new()
    .symbol("€")
    .precision(2)
    .thousands_separator('.')
    .decimal_separator(',');

let price: Decimal = "1234.5".parse().unwrap();
assert_eq!(opts.format(price).into_string(), "€1.234,50");

Pluralize and truncate escape hatches

pluralize covers common English rules (sibilant endings, consonant+y, and a handful of irregulars like person/people). For irregulars it misses, use pluralize_with with an explicit plural:

pluralize_with(count, "octopus", "octopi")

truncate/truncate_words default to an "…" ellipsis and never split a UTF-8 character mid-byte; use truncate_with/truncate_words_with for a custom marker (e.g. " [read more]").

Deterministic relative time in tests

time_ago_in_words takes now as a plain DateTime<Utc> — pass clock.now() from the Clock extractor in handlers, or from any ClockSource (like FixedClock) in tests for exact, non-flaky output:

use autumn_web::prelude::*;
use autumn_web::time::{ClockSource, FixedClock};
use chrono::{TimeZone, Utc};

let posted_at = Utc.with_ymd_and_hms(2026, 1, 1, 11, 58, 0).unwrap();
let now = FixedClock::at(Utc.with_ymd_and_hms(2026, 1, 1, 12, 0, 0).unwrap()).now();
assert_eq!(time_ago_in_words(posted_at, now).into_string(), "2 minutes ago");

Out of scope

Single-locale only (configurable separators/symbol, not full CLDR/ICU locale catalogs) — see the i18n guide for message translation. No number-to-words, ordinalize, or file-size humanizers yet; no auto-formatting wired into scaffolded views (scaffolds still emit the raw value — call these helpers explicitly in the generated template).