# `DateRange`

The days from one date to another, both included: `2026-10-01/2026-10-31`.

Use it for bookings, holidays and reporting periods. For moments, use [`InstantRange`](/docs/types/type-instant-range.md), which leaves out its end. For a range of any other ordered type, use [`Range`](/docs/types/type-range.md).

## Shape

| Field | Type | Required? |
|---|---|---|
| `start` | [`CalendarDate`](/docs/types/type-calendar-date.md) | Yes |
| `end` | [`CalendarDate`](/docs/types/type-calendar-date.md) | Yes |

Its parts keep these rules, and a value that breaks one fails with the rule's name:

- `start_not_after_end`: start <= end

## Example

```jadpo
DateRange { start: "2026-10-01" end: "2026-10-31" }
```

`text.parse(raw, as: DateRange)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `2026-10-31/2026-10-01`, `2026-10-01` or `2026-10-01/..`.

This operation gives one: `range.intersection`.

## Good to know

- Unlike every other range, the last day counts: a one-day range has `start` and `end` on the same date.
- `range.contains`, `range.overlaps` and `range.intersection` work on it.
- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it, so sort by one of its parts instead.

## In JSON

An object of its parts, in a request, a response or `json.write`:

```json
{"start":"2026-10-01","end":"2026-10-31"}
{"start":"2026-10-25","end":"2026-10-25"}
```

## Details

<details>
<summary>Text form, storage, how it is shown, and operations</summary>

`DateRange` is in the group Time and calendar, and has been in Jadpo since 0.1.0.

### Text form

`text.from` writes one standard text form, the same form `text.parse` reads back: `2026-10-01/2026-10-31` and `2026-10-25/2026-10-25`.

### How it is stored

It is stored in one column named for the field, of type `daterange`. `2026-10-25/2026-10-25` is stored as `daterange('2026-10-25'::date, '2026-10-25'::date, '[]')`.

### How it is shown to people

`text.format(value, locale:)` shows it to people in their locale. A call also gives `format:`.

With `locale: Locale.en_gb` and `format: TimeFormat.date_medium`:

| Value | Shown |
|---|---|
| `2026-10-01/2026-10-31` | `1 Oct 2026 – 31 Oct 2026` |
| `2026-10-25/2026-10-25` | `25 Oct 2026 – 25 Oct 2026` |

### Operations

- `range.contains(range: Range<T>, value: T) -> Bool`: Whether `value` is inside `range`.
- `range.intersection(a: Range<T>, b: Range<T>) -> Range<T>?`: The part `a` and `b` share; `none` when they don't overlap.
- `range.overlaps(a: Range<T>, b: Range<T>) -> Bool`: Whether `a` and `b` share at least one value.

It also takes `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. [How every standard type behaves](/docs/every-standard-type-meets-one-contract.md) says how they work.

</details>