active_model_serializers/docs/general/key_transforms.md

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Key Transforms

Key Transforms modify the casing of keys and keys referenced in values in serialized responses.

Provided key transforms:

Option	Result
:camel	ExampleKey
:camel_lower	exampleKey
:dash	example-key
:unaltered	the original, unaltered key
:underscore	example_key
nil	use the adapter default

Key translation precedence is as follows:

Adapter option

key_transform is provided as an option via render.

render json: posts, each_serializer: PostSerializer, key_transform: :camel_lower

Configuration option

key_transform is set in ActiveModelSerializers.config.key_transform.

ActiveModelSerializers.config.key_transform = :camel_lower

Adapter default

Each adapter has a default transform configured:

Adapter	Default Key Transform
Json	:unaltered
JsonApi	:dash