# `BloodType`

A person's blood group: `O-`, `AB+` and so on.

Use it in medical records, or wherever else someone's blood group is recorded.

## Shape

One of these 8 values:

| Value | Written |
|---|---|
| `BloodType.a_positive` | `A+` |
| `BloodType.a_negative` | `A-` |
| `BloodType.ab_positive` | `AB+` |
| `BloodType.ab_negative` | `AB-` |
| `BloodType.b_positive` | `B+` |
| `BloodType.b_negative` | `B-` |
| `BloodType.o_positive` | `O+` |
| `BloodType.o_negative` | `O-` |

## Example

```jadpo
BloodType.o_negative
```

`text.parse(raw, as: BloodType)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `O pos`, `0+` or `O`.

## Good to know

- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it.
- A field that holds one counts as personal data (`health`), so you don't mark it yourself.

## In JSON

A string, in a request, a response or `json.write`:

```json
"AB+"
"O-"
```

## Details

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

`BloodType` is in the group Health, 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: `AB+` and `O-`.

### How it is stored

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

### How it is shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `AB+` | `AB+` |
| `O-` | `O-` |

### Operations

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>