---
url: /reference/concerns/fragmentable.md
---
# Trek::Fragmentable

Composes a record from reusable [fragments](/reference/models/fragment), based on a configuration matrix mapping record keys to the attributes finding each fragment.

## Configuration

In `config/page_fragments.yml`, read with `config_for`, so under `shared:` or an environment's key:

```yaml
shared:
  matrix:
    home:
      - { namespace: home, key: intro }
      - { namespace: home, key: newsletter }
    about:
      - { namespace: about, key: team }
```

Each entry is passed to `Fragment.find_by`. Without the file, a record has no fragments.

## Methods

| Method | Purpose |
| --- | --- |
| `fragments` | the Fragment records configured for this record's `key` |
| `fragments_attributes=` | bulk-updates fragments from nested form attributes |

## Usage

```ruby
class Page < ApplicationRecord
  include Trek::Fragmentable
end

page = Page.find_by(key: "home")
page.fragments # => the home/intro and home/newsletter fragments
```

This is what powers the fragment editing UI on page forms in the admin.