test.cs

[HttpPost]
public string RequestAPI([FromBody] ChatGPTRequest request) {

   HttpClient client = new HttpClient();

   client.DefaultRequestHeaders.Authorization =
      new AuthenticationHeaderValue("Bearer", Models.Constants.OPENAI_API_KEY);

   var openAIPrompt = new {
      model = "text-davinci-003",
      prompt = Models.Constants.Prompts[request.Type] + request.Text.Trim(),
      temperature = 0.2,
      max_tokens = 2048,
      top_p = 1
   };

   var stringContent = new StringContent(JsonConvert.SerializeObject(openAIPrompt), Encoding.UTF8, "application/json");
   var result = client.PostAsync("https://api.openai.com/v1/completions", stringContent).Result;
   var jsonContent = result.Content.ReadAsStringAsync().Result;
   ChatGPTResponse chatGPTResponse = JsonConvert.DeserializeObject<ChatGPTResponse>(jsonContent);

   return chatGPTResponse.Choices[0].Text.Trim();
}