Skip to main content

SKPromptGenerator by Charlie Chen

NuGet / site data​

Nuget GitHub last commit GitHub Repo stars

Details​

Info​

info

Name: SKPromptGenerator

A source generator to automatically create classes from string prompts.

Author: Charlie Chen

NuGet: https://www.nuget.org/packages/SKPromptGenerator/

You can find more details at https://github.com/CharlieDigital/SKPromptGenerator

Source: https://github.com/CharlieDigital/SKPromptGenerator

Author​

note

Charlie Chen Alt text

Original Readme​

note

Semantic Kernel (SK) Prompt Generator

SKPromptGenerator is a C# source generator which automatically creates strongly-typed classes for your string prompt templates.

It is intended to be used with Semantic Kernel.

https://github.com/user-attachments/assets/a3727ef4-6880-4939-be40-5c5c08948a3e

💡 NOTE: As of version 4, the token format is switched from {name} to {{$name}} to match Semantic Kernel.

Motivation​

When working with prompts, you'll end up doing a lot of string templating and repetitive code.

Wouldn't it be nice if you could just have a strongly-typed class for each prompt automatically created using the prompt?

This library does exactly that.

public static class Prompts
{
  // Define a prompt
  [PromptTemplate]
  public const string Capitol = """
    What is the capitol of {{$state}} {{$country}}?
    Respond directly in a single line
    """;
}

// Execute the prompt passing in a Semantic Kernel instance.
var capitol = await new CapitolPrompt(
  state: "NJ",
  country: "USA"
).ExecuteAsync(kernel);

The tokens in the prompt string become named parameters on the class constructor 🎉

Limitations​

  1. Your prompt must be a const string because the generator needs to be able to read the string in the source.
  2. Your prompts must live in some class in a namespace. If you get the error error CS1001: Identifier expected, then you are probably missing a namespace around your prompt.
  3. You must add a dependency to Microsoft.SemanticKernel since the ExecuteAsync method requires the Kernel instance.
  4. Currently only targets .NET 8; considering netstandard2.0.

Installing​

This generator is built for .NET 8.

To install:

dotnet add package SKPromptGenerator

For the latest releases, see: https://www.nuget.org/packages/SKPromptGenerator

Using​

This repository includes a sample project under the /app directory.

To use, create a new console app:

mkdir sk-prompt-gen-test
cd sk-prompt-gen-test
dotnet new console
dotnet add package SKPromptGenerator
dotnet add package Microsoft.SemanticKernel

In the project, create a class like so (you can call your class whatever you want):

namespace SomeNamespace;

public static class Prompts
{
  [PromptTemplate]
  public const string Capitol = """
    What is the capitol of {{$state}} {{$country}}?
    Respond directly in a single line
    When writing the state, always write it as the full name
    Write your output in the format: The capitol of <STATE> is: <CAPITOL>.
    For example: The capitol of California is: Sacramento.
    """;
}

💡 Note the usage of a namespace for the class. The prompt need not be in a standalone class. It can also be placed in an existing Controller (for example)

In the code above, we've created a prompt with two tokens: {{$state}} and {{$country}}.

The [PromptTemplate] attribute instructs the generator to create a class like so:

using System;
using Microsoft.SemanticKernel.Connectors.OpenAI;
using SKPromptGenerator;

namespace SomeNamespace;

public partial class CapitolPrompt(
  string state, string country
) : PromptTemplateBase
{
  public override string Text => $$"""
What is the capitol of {{state}} {{country}}?
Respond directly in a single line
When writing the state, always write it as the full name
Write your output in the format: The capitol of <STATE> is: <CAPITOL>.
For example: The capitol of California is: Sacramento.
""";

  public override OpenAIPromptExecutionSettings Settings => new OpenAIPromptExecutionSettings
  {
    MaxTokens = 500,
    Temperature = 0.5d,
    TopP = 0d,
  };
}

Note the two class parameters state and country which are extracted from the prompt template are now string literal tokens.

Now we can use the prompt like so:

var capitol = await new CapitolPrompt("NJ", "USA").ExecuteAsync(kernel);

Console.WriteLine($"{capitol}");
// The capitol of New Jersey is: Trenton.

capitol = await new CapitolPrompt("NY", "USA").ExecuteAsync(kernel);

Console.WriteLine($"{capitol}");
// The capitol of New York is: Albany.

If your prompt returns JSON, we can also deserialize it into an object:

// Our model that we are serializing to
public record CapitolResponse(string Country, string State, string Capitol);

// Use ExecuteWithJsonAsync if we also want the raw JSON
var (sacramento, json) = await new CapitolJsonPrompt(
  "CA",
  "US"
).ExecuteWithJsonAsync<CapitolResponse>(kernel);

NOTE: The underlying code will strip Markdown fences so if you are expecting your result to contain markdown, it will be stripped.

Typed Parameters​

If you want to use typed parameters, you can append the type to the parameter token:

[PromptTemplate]
public const string Cities = """
  Write a list of {{$count:int}} cities in {{$region}}, {{$country}}
  Write each city on a separate line
  Start you response with: Sure, here are {{$count:int}} cities in {{$region}}, {{$country}}
  """;

This will generate the signature:

public partial class CitiesPrompt(
  int count, string region, string country
) : PromptTemplateBase

Which can then be invoked with a typed, integer parameter for count:

var njCities = await new CitiesPrompt(4, "NJ", "USA").ExecuteAsync(kernel);

This will output:

Sure, here are 4 cities in NJ, USA:

1. Newark
2. Jersey City
3. Paterson
4. Elizabeth

Note that if you are using your own types, those types should be added using a global using statement or specify the full type name since the generated class does not know about your namespaces.

(See the example in the /app directory for usage)

Including History​

The ExecuteAsync method takes a historyBuilder parameter which will receives a ChatHistory instance

The unit tests show how this can be used:

[Fact]
public async void History_Builder_Test()
{
  var response = await new HistoryTmplPrompt("Spencer").ExecuteAsync(
    new Kernel(),
    // 👇 Here we can build the chat history up before adding the new user prompt
    historyBuilder: (h) =>
    {
      h.Add(new ChatMessageContent(AuthorRole.User, "User question"));
      h.Add(new ChatMessageContent(AuthorRole.System, "System response"));
    }
  );

  // Fake test where we are just going to return the history instead
  Assert.Equal("User question\nSystem response", response);
}

You can do the retrieval of the actual history before the block and then do the history building in the block.

Custom Base Class​

If you want to customize how the prompt is executed, you can specify a custom base class when assigning the attribute.

Your base class must inherit from PromptTemplateBase:

public abstract class CustomBase : PromptTemplateBase
{
  public override async Task<string> ExecuteAsync(
    Kernel kernel,
    string? serviceId = null,
    CancellationToken cancellation = default
  )
  {
    return await Task.FromResult("response");
  }
}

And then you can specify this custom base class as a generic type:

[PromptTemplate<CustomBase>]
public const string CapitolCustom = """
  What is the capitol of {{$state}} {{$country}}?
  Respond directly in a single line
  When writing the state, always write it as the full name
  Write your output in the format: The capitol of <STATE> is: <CAPITOL>.
  For example: The capitol of California is: Sacramento.
  """;

This allows you to take full control of the execution of the prompt (e.g. add logging, telemetry, etc.).

💡 Note: you should use a global using statement for the namespace of your custom base class.

Prompt Execution Settings​

The PromptTemplate attribute also allows specification of the prompt execution settings.

The three parameters are:

ParameterDetailsDefault
MaxTokensThe maximum number of tokens in the response500
TemperatureThe temperature0.5
TopPThe TopP0

For example:

public static class Prompts
{
  [PromptTemplate(10, 0.1)]
  public const string SampleTmpl1 = """
    What is the capitol of {{$state}} {{$country}}
    Respond directly on a single line.
    """;
}

(See the PromptTmpl class for details)

Using the Sample App​

To use the sample app, you'll need to set up user secrets:

dotnet user-secrets init
dotnet user-secrets set "AzureOpenAIKey" "YOUR_AZURE_OPEN_AI_KEY"
dotnet user-secrets set "AzureOpenAIEndpoint" "YOUR_AZURE_OPEN_AI_ENDPOINT"

If you are using OpenAI, feel free to fork this project and simply change the service type and configuration values.

About​

note

Generate typed prompts for Semantic Kernel

How to use​

Example (source csproj, source files)​

This is the CSharp Project that references SKPromptGenerator

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.SemanticKernel" Version="1.64.0" />
    <PackageReference Include="SKPromptGenerator" Version="0.5.1">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
  </ItemGroup>
	<PropertyGroup>
		<EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
		<CompilerGeneratedFilesOutputPath>$(BaseIntermediateOutputPath)\GX</CompilerGeneratedFilesOutputPath>
	</PropertyGroup>
</Project>

Generated Files​

Those are taken from $(BaseIntermediateOutputPath)\GX

using System;
using Microsoft.SemanticKernel.Connectors.OpenAI;
using SKPromptGenerator;

namespace DemoAI;

/// <summary>
/// Generated prompt for `Weather`
/// </summary>
public partial class WeatherPrompt(
  string city
) : PromptTemplateBase
{
  /// <summary>
  /// The base prompt template string for `Weather`
  /// </summary>
  public override string Text => $$"""
What is the weather in the city {{city}} ?
Respond directly in a single line
""";

  /// <summary>
  /// Settings for the prompt `Weather`:
  ///   MaxTokens = 500
  ///   Temperature = 0.5d
  ///   TopP = 0d
  /// </summary>
  public override OpenAIPromptExecutionSettings Settings => new OpenAIPromptExecutionSettings
  {
    MaxTokens = 500,
    Temperature = 0.5d,
    TopP = 0d,
  };
}

Useful​

Download Example (.NET C#)​

tip

Download Example project SKPromptGenerator

Share SKPromptGenerator​

https://ignatandrei.github.io/RSCG_Examples/v2/docs/SKPromptGenerator

aaa

Category "AI" has the following generators:​

1 SKPromptGenerator Nuget GitHub Repo stars 2025-08-07

See category​

AI