Python configuration | Fern Documentation

Configure the Python SDK in the generation block of its target in sdk-config.yml:

sdk-config.yml

targets:
  - language: python
    generation:
      naming:
        clientName: YourClientName
      followRedirectsByDefault: true
      alwaysInitializeOptionals: true
      useTypedDictRequests: true

The target’s generation block also accepts the shared generation options, such as naming, wireTests, and customCode. Shared options set in the top-level generation block apply to every target, and a target’s generation block overrides them. For generators.yml options, see the Legacy Python configuration.

Python options

pythonVersion

string

The Python version targeted by the generated project.

pydanticVersion

string

The Pydantic dependency version requirement.

pydantic

object

Pydantic model-generation behavior.

<ParamField path=“pydantic.versionCompatibility” type=""v1” | “v2” | “both” | “v1-on-v2"" required= toc=> The Pydantic major versions supported by generated models. </ParamField>

pydantic.frozen

boolean

Whether generated Pydantic models are immutable.

pydantic.requireOptionalFields

boolean

Whether Optional fields remain required unless they declare a default.

<ParamField path=“pydantic.unionNaming” type=""v0” | “v1"" required= toc=> The naming strategy for generated union types. </ParamField>

pydantic.useFieldAliases

boolean

Whether Pydantic field aliases preserve wire names.

client

object

Python client file naming.

client.fileName

string

The source file name for the Python client.

client.exportedFileName

string

The file name used when exporting the Python client.

followRedirectsByDefault

boolean

Whether generated HTTP clients follow redirects by default.

defaultBytesStreamChunkSize

number

The default byte-stream iterator chunk size.

recursionLimit

number

The Python recursion limit installed when the generated package is imported.

extras

object

Published Python extras and their dependency names.

alwaysInitializeOptionals

boolean

Whether optional model fields are initialized even when omitted.

useTypedDictRequests

boolean

Whether request bodies are generated as TypedDict types.

additionalInitExports

list of object

Additional names re-exported from the package initializer.