# `TraceParent`

A `traceparent` header's value (W3C Trace Context, version `00`): `00-<trace id>-<span id>-<flags>`.

[Software](types.md#software); not ordered; since Jadpo 0.1.0.

## Make one

Build one from its text, `TraceParent("00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01")`, which checks it: text that isn't one breaks `format`.

`text.parse(raw, as: TraceParent)` reads one from its text; text that isn't one at all fails `malformed`, such as `""`.

## 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 |
|---|---|
| `00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01` | `"00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01"` |
| `00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-00` | `"00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-00"` |

It is stored in one column named for the field, of type `text`. `00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-00` is stored as `'00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-00'`.

## Shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01` | `00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01` |
| `00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-00` | `00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-00` |

## 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.