Binary data and files

Use the bytes type to handle binary data in your API

Fern Definition isn’t recommended for new customers and Fern isn’t accepting feature requests for this format. It remains supported for existing users.

The bytes type allows you to handle binary data in both requests and responses.

Sending bytes

If your API needs to send a stream of bytes (i.e. typical for assets like audio, images and other files) then you can use the bytes type in the Fern Definition to model this.

audio.yml

1 service:
2   base-path: /audio
3   endpoints:
4     upload:
5       display-name: Upload audio
6       method: POST
7       path: /upload
8       content-type: application/octet-stream
9       request:
10         type: bytes
11         docs: The bytes of the MP3 file that you would like to upload

Receiving bytes

When handling binary data in responses, use type: file instead of type: bytes.

On the other hand, if your API is returning a stream of bytes, then you can leverage the bytes type as a response.

textToSpeech.yml

1 service:
2   base-path: /tts
3   endpoints:
4     upload:
5       display-name: Upload audio
6       method: POST
7       path: ""
8       request:
9         name: TTSRequest
10         body:
11           properties:
12             text:
13               type: string
14               docs: The text that you want converted to speech.
15       response:
16         type: file
17         docs: The bytes of the audio file.

1	service:
2	base-path: /audio
3	endpoints:
4	upload:
5	display-name: Upload audio
6	method: POST
7	path: /upload
8	content-type: application/octet-stream
9	request:
10	type: bytes
11	docs: The bytes of the MP3 file that you would like to upload

1	service:
2	base-path: /tts
3	endpoints:
4	upload:
5	display-name: Upload audio
6	method: POST
7	path: ""
8	request:
9	name: TTSRequest
10	body:
11	properties:
12	text:
13	type: string
14	docs: The text that you want converted to speech.
15	response:
16	type: file
17	docs: The bytes of the audio file.