Set up local SDK previews

Once you configure your SDK, you can use the --preview flag to test generated SDK code locally before publishing. This allows quick iteration on your SDK as you develop:

$
# Preview all SDKs
>
fern generate --preview
>
>
# Preview SDK for a specific language
>
fern generate --group <language>-sdk --preview

--preview generates your SDK code into a local .preview/ folder within your fern folder. No changes are published to package managers or GitHub.

Example usage

Here’s an example of how you can preview a Python SDK.

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api: 
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  path: ./path/to/openapi.yml
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groups:
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  python-sdk:
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    generators:
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      - name: fernapi/fern-python-sdk
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        version: 4.25.6
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        output:
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          location: pypi
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          package-name: imdb
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          token: ${PYPI_TOKEN}
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        github:
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          repository: imdb/imdb-python
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        config:
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          client_class_name: imdb

$
fern generate --group python-sdk --preview

$
fern/
>
  ├─ fern.config.json
>
  ├─ .preview/
>
    └─ fern-python-sdk/
>
      └─ ...
>
  ├─ generators.yml
>
  └─ openapi/
>
    └─ openapi.yml