ChatGptNet 2.0.11

ChatGPT for .NET

A ChatGPT integration library for .NET, supporting both OpenAI and Azure OpenAI Service.

Installation

The library is available on NuGet. Just search for ChatGptNet in the Package Manager GUI or run the following command in the .NET CLI:

dotnet add package ChatGptNet

Configuration

Register ChatGPT service at application startup:

builder.Services.AddChatGpt(options =>
{
    // OpenAI.
    //options.UseOpenAI(apiKey: "", organization: "");

    // Azure OpenAI Service.
    //options.UseAzure(resourceName: "", apiKey: "", authenticationType: AzureAuthenticationType.ApiKey);

    options.DefaultModel = "my-model";
    options.MessageLimit = 16;  // Default: 10
    options.MessageExpiration = TimeSpan.FromMinutes(5);    // Default: 1 hour
});

ChatGptNet supports both OpenAI and Azure OpenAI Service, so it is necessary to set the correct configuration settings based on the chosen provider:

OpenAI (UseOpenAI)

• ApiKey: it is available in the User settings page of the OpenAI account (required).
• Organization: for users who belong to multiple organizations, you can also specify which organization is used. Usage from these API requests will count against the specified organization's subscription quota (optional).

Azure OpenAI Service (UseAzure)

• ResourceName: the name of your Azure OpenAI Resource (required).
• ApiKey: Azure OpenAI provides two methods for authentication. You can use either API Keys or Azure Active Directory (required).
• AuthenticationType: it specifies if the key is an actual API Key or an Azure Active Directory token (optional, default: "ApiKey").

DefaultModel

ChatGPT can be used with different models for chat completion, both on OpenAI and Azure OpenAI service. With the DefaultModel property, you can specify the default model that will be used, unless you pass an explicit value in the AskAsync method:

OpenAI

Currently available models are: gpt-3.5-turbo, gpt-4 and gpt-4-32k. They have fixed names, available in the OpenAIChatGptModels.cs file.

Note The gpt-4 and gpt-4-32k models are currently in a limited beta and only accessible to those who have been granted access. You can find more information in the models documentation page of the OpenAI site.

Azure OpenAI Service

In Azure OpenAI Service, you're required to first deploy a model before you can make calls. When you deploy a model, you need to assign it a name, that must match the name you use with ChatGptNet.

Note Some models are not available in all regions. You can refer to Model Summary table and region availability page to check current availabilities.

Caching, MessageLimit and MessageExpiration

ChatGPT is aimed to support conversational scenarios: user can talk to ChatGPT without specifying the full context for every interaction. However, conversation history isn't managed by OpenAI or Azure OpenAI service, so it's up to us to retain the current state. By default, ChatGptNet handles this requirement using a MemoryCache that stores messages for each conversation. The behavior can be set using the following properties:

• MessageLimit: specifies how many messages for each conversation must be saved. When this limit is reached, oldest messages are automatically removed.
• MessageExpiration: specifies the time interval used to maintain messages in cache, regardless their count.

If necessary, it is possibile to provide a custom Cache by implementing the IChatGptCache interface and then calling the WithCache extension method:

public class LocalMessageCache : IChatGptCache
{
    private readonly Dictionary<Guid, List<ChatGptMessage>> localCache = new();

    public Task SetAsync(Guid conversationId, IEnumerable<ChatGptMessage> messages, TimeSpan expiration)
    {
        localCache[conversationId] = messages.ToList();
        return Task.CompletedTask;
    }

    public Task<List<ChatGptMessage>?> GetAsync(Guid conversationId)
    {
        localCache.TryGetValue(conversationId, out var messages);
        return Task.FromResult(messages);
    }

    public Task RemoveAsync(Guid conversationId)
    {
        localCache.Remove(conversationId);
        return Task.CompletedTask;
    }
}

// Registers the custom cache at application startup.
builder.Services.AddChatGpt(/* ... */).WithCache<LocalMessageCache>();

We can also set ChatGPT parameters for chat completion at startup. Check the official documentation for the list of available parameters and their meaning.

Configuration using an external source

The configuration can be automatically read from IConfiguration, using for example a ChatGPT section in the appsettings.json file:

"ChatGPT": {
    "Provider": "OpenAI",           // Optional. Allowed values: OpenAI (default) or Azure
    "ApiKey": "",                   // Required
    //"Organization": "",           // Optional, used only by OpenAI
    "ResourceName": "",             // Required when using Azure OpenAI Service
    "AuthenticationType": "ApiKey", // Optional, used only by Azure OpenAI Service. Allowed values : ApiKey (default) or ActiveDirectory

    "DefaultModel": "my-model",
    "MessageLimit": 20,
    "MessageExpiration": "00:30:00",
    "ThrowExceptionOnError": true
    //"User": "UserName",
    //"DefaultParameters": {
    //    "Temperature": 0.8,
    //    "TopP": 1,
    //    "MaxTokens": 500,
    //    "PresencePenalty": 0,
    //    "FrequencyPenalty": 0
    //}
}

And then use the corresponding overload of che AddChatGpt method:

// Adds ChatGPT service using settings from IConfiguration.
builder.Services.AddChatGpt(builder.Configuration);

Configuring ChatGptNet dinamically

The AddChatGpt method has also an overload that accepts an IServiceProvider as argument. It can be used, for example, if we're in a Web API and we need to support scenarios in which every user has a different API Key that can be retrieved accessing a database via Dependency Injection:

builder.Services.AddChatGpt((services, options) =>
{
    var accountService = services.GetRequiredService<IAccountService>();

    // Dynamically gets the API Key from the service.
    var apiKey = "..."        

    options.UseOpenAI(apiKyey);
});

Configuring ChatGptNet using both IConfiguration and code

In more complex scenarios, it is possible to configure ChatGptNet using both code and IConfiguration. This can be useful if we want to set a bunch of common properties, but at the same time we need some configuration logic. For example:

builder.Services.AddChatGpt((services, options) =>
{
    // Configure common properties (message limit and expiration, default parameters, ecc.) using IConfiguration.
    options.UseConfiguration(builder.Configuration);

    var accountService = services.GetRequiredService<IAccountService>();

    // Dynamically gets the API Key from the service.
    var apiKey = "..."        

    options.UseOpenAI(apiKyey);
});

Usage

The library can be used in any .NET application built with .NET 6.0 or later. For example, we can create a Minimal API in this way:

app.MapPost("/api/chat/ask", async (Request request, IChatGptClient chatGptClient) =>
{
    var response = await chatGptClient.AskAsync(request.ConversationId, request.Message);
    return TypedResults.Ok(response);
})
.WithOpenApi();

// ...

public record class Request(Guid ConversationId, string Message);

If we just want to retrieve the response message, we can call the GetMessage method:

var message = response.GetMessage();

Handling a conversation

The AskAsync method has an overload (the one shown in the example above) that requires a conversationId parameter. If we pass an empty value, a random one is generated and returned. We can pass this value in subsequent invocations of AskAsync so that the library automatically retrieves previous messages of the current conversation (according to MessageLimit and MessageExpiration settings) and send them to chat completion API.

Response streaming

Chat completion API supports response streaming. When using this feature, partial message deltas will be sent, like in ChatGPT. Tokens will be sent as data-only server-sent events as they become available. ChatGptNet provides response streaming using the AskStreamAsync method:

// Requests a streaming response.
var responseStream = chatGptClient.AskStreamAsync(conversationId, message);

await foreach (var response in responseStream)
{
    Console.Write(response.GetMessage());
    await Task.Delay(80);
}

Response streaming works by returning an IAsyncEnumerable, so it can be used even in a Web API project:

app.MapGet("/api/chat/stream", (Guid? conversationId, string message, IChatGptClient chatGptClient) =>
{
    async IAsyncEnumerable<string> Stream()
    {
        // Requests a streaming response.
        var responseStream = chatGptClient.AskStreamAsync(conversationId.GetValueOrDefault(), message);

        // Uses the "AsDeltas" extension method to retrieve partial message deltas only.
        await foreach (var delta in responseStream.AsDeltas())
        {
            yield return delta;
            await Task.Delay(50);
        }
    }

    return Stream();
})
.WithOpenApi();

The library is 100% compatible also with Blazor WebAssembly applications:

Check the Samples folder for more information about the different implementations.

Changing the assistant's behavior

ChatGPT supports messages with the system role to influence how the assistant should behave. For example, we can tell to ChatGPT something like that:

• You are an helpful assistant
• Answer like Shakespeare
• Give me only wrong answers
• Answer in rhyme

ChatGptNet provides this feature using the SetupAsync method:

var conversationId await = chatGptClient.SetupAsync("Answer in rhyme");

If we use the same conversationId when calling AskAsync, then the system message will be automatically sent along with every request, so that the assistant will know how to behave.

Note The system message does not count for messages limit number.

Deleting a conversation

Conversation history is automatically deleted when expiration time (specified by MessageExpiration property) is reached. However, if necessary it is possible to immediately clear the history:

await chatGptClient.DeleteConversationAsync(conversationId, preserveSetup: false);

The preserveSetup argument allows to decide whether mantain also the system message that has been set with the SetupAsync method (default: false).

Contribute

The project is constantly evolving. Contributions are welcome. Feel free to file issues and pull requests on the repo and we'll address them as we can.

Warning Remember to work on the develop branch, don't use the master branch directly. Create Pull Requests targeting develop.