Quickstart: Create a knowledge base in QnA Maker using C#

This quickstart walks you through programmatically creating and publishing a sample QnA Maker knowledge base. QnA Maker automatically extracts questions and answers from semi-structured content, like FAQs, from data sources. The model for the knowledge base is defined in the JSON sent in the body of the API request.

This quickstart calls QnA Maker APIs:



The complete solution file(s) are available from the Azure-Samples/cognitive-services-qnamaker-csharp GitHub repository.

Create a knowledge base project

  1. Open Visual Studio 2019 Community edition.
  2. Create a new Console App (.NET Core) project and name the project QnaMakerQuickstart. Accept the defaults for the remaining settings.
  3. In the Solution Explorer, right-click on the project name, QnaMakerQuickstart, then select Manage NuGet Packages....
  4. In the NuGet window, select Browser, then search for Newtonsoft.JSON and install the package. This package is used to parse the JSON returned from the QnaMaker HTTP response.

Add the required dependencies

At the top of Program.cs, replace the single using statement with the following lines to add necessary dependencies to the project:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

// NOTE: Install the Newtonsoft.Json NuGet package.
using Newtonsoft.Json;

Add the required constants

At the top of the Program class, add the following constants to access QnA Maker:

// Represents the various elements used to create HTTP request URIs
// for QnA Maker operations.
static string host = "https://westus.api.cognitive.microsoft.com";
static string service = "/qnamaker/v4.0";
static string method = "/knowledgebases/create";

// NOTE: Replace this value with a valid QnA Maker subscription key.
static string key = "your-qna-maker-subscription-key";

Add the KB definition

After the constants, add the following KB definition:

        static string kb = @"
  'name': 'QnA Maker FAQ',
  'qnaList': [
      'id': 0,
      'answer': 'You can use our REST APIs to manage your knowledge base. See here for details: https://westus.dev.cognitive.microsoft.com/docs/services/58994a073d9e04097c7ba6fe/operations/58994a073d9e041ad42d9baa',
      'source': 'Custom Editorial',
      'questions': [
        'How do I programmatically update my knowledge base?'
      'metadata': [
          'name': 'category',
          'value': 'api'
  'urls': [
  'files': []

Add supporting functions and structures

Add the following code block inside the Program class:

public struct Response
    public HttpResponseHeaders headers;
    public string response;

    public Response(HttpResponseHeaders headers, string response)
        this.headers = headers;
        this.response = response;

/// <summary>
/// Formats and indents JSON for display.
/// </summary>
/// <param name="s">The JSON to format and indent.</param>
/// <returns>A string containing formatted and indented JSON.</returns>
static string PrettyPrint(string s)
    return JsonConvert.SerializeObject(JsonConvert.DeserializeObject(s), Formatting.Indented);

Add a POST request to create KB

The following code makes an HTTPS request to the QnA Maker API to create a KB and receives the response:

async static Task<Response> Post(string uri, string body)
    using (var client = new HttpClient())
    using (var request = new HttpRequestMessage())
        request.Method = HttpMethod.Post;
        request.RequestUri = new Uri(uri);
        request.Content = new StringContent(body, Encoding.UTF8, "application/json");
        request.Headers.Add("Ocp-Apim-Subscription-Key", key);

        var response = await client.SendAsync(request);
        var responseBody = await response.Content.ReadAsStringAsync();
        return new Response(response.Headers, responseBody);

This API call returns a JSON response that includes the operation ID. Use the operation ID to determine if the KB is successfully created.

  "operationState": "NotStarted",
  "createdTimestamp": "2018-09-26T05:19:01Z",
  "lastActionTimestamp": "2018-09-26T05:19:01Z",
  "userId": "XXX9549466094e1cb4fd063b646e1ad6",
  "operationId": "8dfb6a82-ae58-4bcb-95b7-d1239ae25681"

Add GET request to determine creation status

Check the status of the operation.

async static Task<Response> GetStatus(string operation)
    // Builds the HTTP request URI.
    string uri = host + service + operation;

    // Writes the HTTP request URI to the console, for display purposes.
    Console.WriteLine("Calling " + uri + ".");

    // Asynchronously invokes the Get(string) method, using the
    // HTTP request URI.
    return await Get(uri);

This API call returns a JSON response that includes the operation status:

  "operationState": "NotStarted",
  "createdTimestamp": "2018-09-26T05:22:53Z",
  "lastActionTimestamp": "2018-09-26T05:22:53Z",
  "userId": "XXX9549466094e1cb4fd063b646e1ad6",
  "operationId": "177e12ff-5d04-4b73-b594-8575f9787963"

Repeat the call until success or failure:

  "operationState": "Succeeded",
  "createdTimestamp": "2018-09-26T05:22:53Z",
  "lastActionTimestamp": "2018-09-26T05:23:08Z",
  "resourceLocation": "/knowledgebases/XXX7892b-10cf-47e2-a3ae-e40683adb714",
  "userId": "XXX9549466094e1cb4fd063b646e1ad6",
  "operationId": "177e12ff-5d04-4b73-b594-8575f9787963"

Add CreateKB method

The following method creates the KB and repeats checks on the status. The create Operation ID is returned in the POST response header field Location, then used as part of the route in the GET request. Because the KB creation may take some time, you need to repeat calls to check the status until the status is either successful or fails. When the operation succeeds, the KB ID is returned in resourceLocation.

async static void CreateKB()
        // Starts the QnA Maker operation to create the knowledge base.
        var response = await PostCreateKB(kb);

        // Retrieves the operation ID, so the operation's status can be
        // checked periodically.
        var operation = response.headers.GetValues("Location").First();

        // Displays the JSON in the HTTP response returned by the 
        // PostCreateKB(string) method.

        // Iteratively gets the state of the operation creating the
        // knowledge base. Once the operation state is set to something other
        // than "Running" or "NotStarted", the loop ends.
        var done = false;
        while (true != done)
            // Gets the status of the operation.
            response = await GetStatus(operation);

            // Displays the JSON in the HTTP response returned by the
            // GetStatus(string) method.

            // Deserialize the JSON into key-value pairs, to retrieve the
            // state of the operation.
            var fields = JsonConvert.DeserializeObject<Dictionary<string, string>>(response.response);

            // Gets and checks the state of the operation.
            String state = fields["operationState"];
            if (state.CompareTo("Running") == 0 || state.CompareTo("NotStarted") == 0)
                // QnA Maker is still creating the knowledge base. The thread is 
                // paused for a number of seconds equal to the Retry-After header value,
                // and then the loop continues.
                var wait = response.headers.GetValues("Retry-After").First();
                Console.WriteLine("Waiting " + wait + " seconds...");
                Thread.Sleep(Int32.Parse(wait) * 1000);
                // QnA Maker has completed creating the knowledge base. 
                done = true;
        // An error occurred while creating the knowledge base. Ensure that
        // you included your QnA Maker subscription key where directed in the sample.
        Console.WriteLine("An error occurred while creating the knowledge base.");
        Console.WriteLine("Press any key to continue.");


Add the CreateKB method to Main

Change the Main method to call the CreateKB method:

static void Main(string[] args)
    // Invoke the CreateKB() method to create a knowledge base, periodically 
    // checking the status of the QnA Maker operation until the 
    // knowledge base is created.

    // The console waits for a key to be pressed before closing.

Build and run the program

Build and run the program. It will automatically send the request to the QnA Maker API to create the KB, then it will poll for the results every 30 seconds. Each response is printed to the console window.

Once your knowledge base is created, you can view it in your QnA Maker Portal, My knowledge bases page.

Clean up resources

When you are done with the quickstart, remove all the files created in this quickstart. Sign on to QnA Maker, and delete the KB.

Next steps