# `Icd10Code`

A diagnosis's ICD-10 code (WHO), with its dot: `I21.9`. Health data.

[Health](types.md#health); not ordered; personal data (health); since Jadpo 0.1.0.

## Make one

Build one from its text, `Icd10Code("I21.9")`, which checks it: text that isn't one breaks `format`.

`text.parse(raw, as: Icd10Code)` reads one from its text; text that isn't one at all fails `malformed`, such as `I219`, `i21.9` or `121.9`.

## 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 |
|---|---|
| `I21.9` | `"I21.9"` |
| `J45` | `"J45"` |
| `S52.521A` | `"S52.521A"` |

It is stored in one column named for the field, of type `text`. `J45` is stored as `'J45'`.

## Shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `I21.9` | `I21.9` |
| `J45` | `J45` |
| `S52.521A` | `S52.521A` |

## Operations

It has the contract's own operations: `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. It isn't ordered, so `<` and sorting don't take it. [Every standard type meets one contract](../topics/every-standard-type-meets-one-contract.md) says how they work.