# `YearMonth`

A month of a year, written `2026-10`: `month` from 1 to 12.

[Time and calendar](types.md#time-and-calendar); ordered; since Jadpo 0.1.0.

## Make one

Build one from its fields, `YearMonth { year: ...  month: ... }`.

`text.parse(raw, as: YearMonth)` reads one from its text; text that isn't one at all fails `malformed`, such as `2026-13`, `2026-00` or `2026-1`.

## Fields

| Field | Type |
|---|---|
| `year` | `Int` |
| `month` | `Int` |

## Text, JSON and storage

`text.from` writes its canonical text, the one form `text.parse` reads back. JSON sends its canonical text as a string.

| Text | JSON |
|---|---|
| `2026-02` | `"2026-02"` |
| `2026-10` | `"2026-10"` |

It is stored in 2 columns, each named for the field, `_` and its suffix. This is `2026-10`:

| Column | Type | Holds |
|---|---|---|
| `<field>_year` | `smallint` | `2026` |
| `<field>_month` | `smallint` | `10` |

## Shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `2026-02` | `February 2026` |
| `2026-10` | `October 2026` |

## Operations

It has the contract's own operations: `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. It is ordered, so `<` and sorting take it. [Every standard type meets one contract](../topics/every-standard-type-meets-one-contract.md) says how they work.