Adding custom code | Fern Documentation

This page covers how to add custom logic and methods to your .NET SDK.

Before getting started, read about how Fern SDKs use custom code and learn about the .fernignore file.

Adding custom logic

To get started adding custom code:

Create a new file and add your custom logic

src/YourNamespace/Helper.cs

1 namespace YourNamespace;
2 
3 public static class Helper
4 {
5     public static void MyHelper()
6     {
7         Console.WriteLine("Hello World!");
8     }
9 }

Add your file to `.fernignore`

.fernignore

1 # Specify files that shouldn't be modified by Fern
2 
3 src/YourNamespace/Helper.cs

Consume the helper

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

1 using YourNamespace;
2 
3 Helper.MyHelper();

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.

Update `generators.yml` configuration

Name your Fern-generated client something like BaseClient to reflect that this client will be extended.

generators.yml

1 - name: fernapi/fern-csharp-sdk
2   version: 2.12.0
3   config:
4     client-class-name: BaseClient

Import and extend the generated client

First, import the Fern generated base client and extend it. Then, add whatever methods you want.

src/YourNamespace/MyClient.cs

1 namespace YourNamespace;
2 
3 public class MyClient : BaseClient
4 {
5     public MyClient(ClientOptions? clientOptions = null) : base(clientOptions)
6     {
7     }
8 
9     public void MyHelper()
10     {
11         Console.WriteLine("Hello World!");
12     }
13 }

Update `.fernignore`

Add the MyClient.cs to .fernignore.