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# Configuration Options

The following configuration options can be set on
`ActiveModelSerializers.config`, preferably inside an initializer.

## General

##### adapter

The [adapter](adapters.md) to use.

Possible values:

- `:attributes` (default)
- `:json`
- `:json_api`

##### serializer_lookup_enabled

Enable automatic serializer lookup.

Possible values:

- `true` (default)
- `false`

When `false`, serializers must be explicitly specified.

##### key_transform

The [key transform](key_transform.md) to use.

Possible values:

- `:camel` - ExampleKey
- `:camel_lower` - exampleKey
- `:dashed` - example-key
- `:unaltered` - the original, unaltered key
- `nil` - use the adapter default

Each adapter has a default key transform configured:

- `Json` - `:unaltered`
- `JsonApi` - `:dashed`

`config.key_transform` is a global override of the adapter default. Adapters
still prefer the render option `:key_transform` over this setting.


## JSON API


##### jsonapi_resource_type

Sets whether the [type](http://jsonapi.org/format/#document-resource-identifier-objects)
of the resource should be `singularized` or `pluralized` when it is not
[explicitly specified by the serializer](https://github.com/rails-api/active_model_serializers/blob/master/docs/general/serializers.md#type)

Possible values:

- `:singular`
- `:plural` (default)

##### jsonapi_include_toplevel_object

Include a [top level jsonapi member](http://jsonapi.org/format/#document-jsonapi-object)
in the response document.

Possible values:

- `true`
- `false` (default)

##### jsonapi_version

The latest version of the spec to which the API conforms.

Default: `'1.0'`.

*Used when `jsonapi_include_toplevel_object` is `true`*

##### jsonapi_toplevel_meta

Optional top-level metadata. Not included if empty.

Default: `{}`.

*Used when `jsonapi_include_toplevel_object` is `true`*


## Hooks

To run a hook when ActiveModelSerializers is loaded, use
`ActiveSupport.on_load(:action_controller) do end`