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      • Adding custom code
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  • Reference
    • generators.yml
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On this page
  • Adding custom logic
  • Adding custom SDK methods
  • Adding custom dependencies
GeneratorsPython

Adding custom code

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Python configuration

Next

Dynamic authentication

This page covers how to add custom logic, methods, and dependencies to your Python SDK.

Adding custom logic

To get started adding custom code:

These steps cover adding a new custom file to the SDK. To preserve line-level edits to a generated file, use Replay instead.
1

Create a new file and add your custom logic

src/<package>/helper.py
1def my_helper() -> None:
2  print("Hello World!")
2

Add your file to .fernignore

.fernignore
1# Specify files that shouldn't be modified by Fern
2
3src/<package>/helper.py
3

Consume the helper

Now your users can consume the helper function by importing it from the SDK.

1from package.helper import my_helper
2
3my_helper()

Adding custom SDK methods

Fern also allows you to add custom methods to the SDK itself (e.g. client.my_method() ) by inheriting the Fern generated client and then extending it.

See an example from ElevenLabs using this process in their Python SDK.

1

Update generators.yml configuration

Name your Fern-generated client something like BaseClient to reflect that this client will be extended. Configure the generator to output the client in a file called base_client.py.

generators.yml
1- name: fernapi/fern-python-sdk
2  version: "..."
3  config:
4    client:
5      class_name: BaseClient        # The name of the generated client you will extend
6      filename: base_client.py      # The name of the file the generated client will live in
7      exported_class_name: YourClient   # The name of the class you will be creating that extends the generated client
8      exported_filename: client.py
2

Generate the SDK

Trigger SDK generation by running fern generate:

$fern generate --group sdk
3

Import and extend the generated client

First, import the Fern generated base clients from .base_client.py and extend them to create your custom clients. Then, add whatever methods you want.

src/<package>/client.py
1  from .base_client import BaseClient // import generated client
2  
3  class YourClient(BaseClient): // extend generated client
4      def my_helper(self) -> None:
5          print("Hello World!")
6          def my_helper(self) -> None:
7              print("Hello World")

See an example client.py from ElevenLabs.

4

Update .fernignore

Add the client.py to .fernignore.

.fernignore
1+ src/<package>/client.py

See an example .fernignore from ElevenLabs.

5

Consume the method

Now your users can consume the helper function by importing it from the SDK.

1client.my_helper()

Adding custom dependencies

Enterprise feature

This feature is available only for the Enterprise plan. To get started, reach out to support@buildwithfern.com.

To add packages that your custom code requires, update your generators.yml.

generators.yml
1- name: fernapi/fern-python-sdk
2  version: "..."
3  config:
4    extra_dependencies:
5      numpy: '1.2.0'
6    extra_dev_dependencies:
7      requests_mock: '1.12.1'