# Identifying users


When a user is logged in to your application, you can attach information about that user to the data you
send, so you can see who was affected in Flare. The user is attached to error reports, to your logs, and to
traces.

Call `flare.setUser()` once you know who the user is (after login, on app boot, in a route guard, etc.):

```javascript
import { flare } from '@flareapp/js';

flare.setUser({
    id: 123,
    email: 'jane@example.com',
    fullName: 'Jane Doe',
});
```

The following fields are recognised:

| Field       | Attribute sent   | Description                                              |
|-------------|------------------|---------------------------------------------------------|
| `id`        | `user.id`        | The user's unique identifier. Used to group occurrences.|
| `email`     | `user.email`     | Shown as the user's label, with a Gravatar.             |
| `fullName`  | `user.full_name` | Shown as the user's label when no email is present.     |

All fields are optional. Provide whichever you have; `id` is what links occurrences to a single user.

## Sending extra attributes

Any additional keys you pass are collected under `user.attributes` and shown alongside the user in Flare:

```javascript
flare.setUser({
    id: 123,
    email: 'jane@example.com',
    fullName: 'Jane Doe',
    plan: 'pro',
    teamId: 42,
});
```

Here `plan` and `teamId` are sent as `user.attributes`.

## Where the user ends up

**Error reports.** Every report sent after `setUser()` carries the user.

![The context pane of an error in Flare, showing the user with their name, email, and attributes](/images/docs/javascript/error-context.png)

**Logs.** Every log record sent after `setUser()` carries the user as well.

**Traces.** The user is attached to the span at the top of a trace, for example a page load or a navigation
span. Child spans inside that trace don't repeat it.

The client reads the user when that top span starts, not when the trace is sent. A page load that started
before you called `setUser()` is sent without a user, even if you set one while the page was still loading.
The next navigation does carry it. If you want the user on the page load itself, call `setUser()` as early
as you can, for example straight after `flare.light()` when you already know who the user is.

## Clearing the user

When the user logs out, clear the attached user by passing `null`:

```javascript
flare.setUser(null);
```

## Per-request scope (Node)

In `@flareapp/node`, `setUser()` attaches the user to the current request scope, so concurrent requests do
not share or leak each other's user. Call it inside your request handler (typically within
`runWithContext(...)`). See the
[`@flareapp/node` README](https://github.com/spatie/flare-client-js/blob/main/packages/node/README.md)
for details on request-scoped context:

```javascript
import { flare } from '@flareapp/node';

flare.setUser({ id: user.id, email: user.email, fullName: user.name });
```