TX Spell .NET is a very powerful spell checking engine with a tight integration into the document editors from Text Control including ASP.NET, Angular and Windows Forms. It provides fully-featured UI elements including dialog boxes and context menus when connected to a Text Control instance.

Non-Visual Spell Engine

But the product also includes the non-visual component TXSpell that can be used for background processing. This sample shows how to use this class to create a spell checking Web API using ASP.NET Core.

Implementing the Web API Controller

The sample implements the Web API controller SpellController:

[Route("api/[controller]")]
[ApiController]
public class SpellController : ControllerBase
{

}

This controller implements 4 endpoints:

• Check
• CreateSuggestions
• CreateSynonyms
• DetectLanguageScopes

The following code shows the implementation of the Check method that accepts the Text to be checked and an optional language identifier:

[HttpGet]
[Route("Check")]
public List<IncorrectWordModel> Check(string text, string language = "en_US")
{
    if (text == null)
        return null;

    // create a new spell checking engine
    TXTextControl.Proofing.TXSpell spell = new TXTextControl.Proofing.TXSpell();
    spell.Create();

    TXTextControl.Proofing.OpenOfficeDictionary dict = 
        new OpenOfficeDictionary(@"Dictionaries\en_US.dic");
    spell.Dictionaries.Add(dict);

    spell.Check(text, new System.Globalization.CultureInfo(language));

    List<IncorrectWordModel> lIncorrectWords = new List<IncorrectWordModel>();

    var incorrectWords = spell.IncorrectWords;

    if (incorrectWords == null)
        return null;

    foreach (IncorrectWord word in incorrectWords)
    {
        lIncorrectWords.Add(new IncorrectWordModel()
        {
            Text = word.Text,
            Index = word.Index,
            IsDuplicate = word.IsDuplicate,
            Length = word.Length,
            Start = word.Start
        });
    }

    return lIncorrectWords;
}

In the method Check, a new instance of the spell checker is created and a dictionary is loaded and added to the available dictionaries using the Dictionaries.Add method.

The given Text is checked using the Check method and the results are returned as a list of IncorrectWords.

Calling from JavaScript

On the JavaScript side, the endpoint is called using a jQuery ajax call:

async function check(text, language = "en_US") {
    var serviceURL = "api/spell/check?text=" + text + "&language=" + language;
    return await callEndpoint(serviceURL);
}

async function callEndpoint(serviceURL) {
  return new Promise(resolve => {
      $.ajax({
          type: "GET",
          url: serviceURL,
          contentType: 'application/json',
          success: successFunc,
          error: errorFunc
      });

      function successFunc(data, status) {
          resolve(data);
      }

      function errorFunc(data) {
          throw "Request failed. Please try again later.";
      }
  });
  }

The spell checking functions are encapsulated in a private scope and exposed as properties in the TXSpell JavaScript object. This way, the check method can be called like this in the sample:

async function checkText() {
    // call the check method
    var results = await TXSpell.check(document.getElementById('textbox').textContent);

    // check console for details
    console.log(results);
    var consoleText = "";

    // loop through the results and return the text
    results.forEach(function (element) {
        consoleText += "<p>Misspelled: <strong>" + element.text + "</strong></p>";
    });

    document.getElementById('results').innerHTML = consoleText;
}

On a button click, the function checkText is called:

<input value="Check" type="button" onclick="checkText()" />

Demo Screenshots

The following screenshot shows the sample after the Check button has been clicked:

Create Suggestions:

Create Synonyms:

Detect Languages:

Download the sample project and test this on your own.