---
title: exist_fragment?.action_controller
description: A Rails fragment cache existence check.
url: https://docs.honeybadger.io/insights/event-types/ruby/exist_fragment_predicate.action_controller/
---

A Rails fragment cache existence check.

Source **Action Controller** Category **Cache** Fields **7** [honeybadger-ruby](https://docs.honeybadger.io/lib/ruby/)

## Fields

| Field             | Type   | Description                                                                                                            |
| ----------------- | ------ | ---------------------------------------------------------------------------------------------------------------------- |
| `event_type`      | string | Allowed value: `exist_fragment?.action_controller`.                                                                    |
| `key`             | string | Fragment cache key.                                                                                                    |
| `duration`        | number | Duration in milliseconds.                                                                                              |
| `instrumenter_id` | string |                                                                                                                        |
| `request_id`      | string | Rails request UUID, present on any event fired during a web request context. Merged globally by the Honeybadger agent. |
| `hostname`        | string | Server hostname. Attached to every event by default (events.attach\_hostname).                                         |
| `environment`     | string | Application environment, e.g. "production". Attached to every event by default (events.attach\_environment).           |

## Example

```json
{
  "event_type": "exist_fragment?.action_controller",
  "key": "views/users/123-20260612143000000000/a1b2c3d4e5f6",
  "duration": 0.31,
  "instrumenter_id": "d6a5b3f4c2e1908a7b6c",
  "request_id": "0f5e4bb2-3c46-4b1c-91d5-2f4e8a6b9c01",
  "hostname": "web-1.example.com",
  "environment": "production"
}
```

---

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