A long time ago, I wrote a blog post about how to translate text in C# using Google Translate. Since then, an official AJAX API has been released, which is a much better solution. Reading the comments of the blog post indicates that the code was broken quite quickly!

Google’s AJAX Language API, also includes functionality to detect language from a given string. All you can do on translate.google.com you can do via the API. Reading the class reference for the Translation API, for Flash and other Non-Javascript environments gives us the information we need to perform translations from C#. Most important is the URL and the parameters required and accepted.

Another very important thing we can read in the documentation is this:

Applications MUST always include a valid and accurate http referer header in their requests

We must remember to add a valid referrer when making the actual call!

The response object

Google’s AJAX Language APIs uses JSON, and returns a JSON object containing 3 properties:

• responseData
• responseDetails
• responseStatus

This means we need to have some C# objects that we can use to deserialize the JSON returned from Google. I’m using a generic class called GoogleAjaxResponse<T>, with T being the specific class I want the JSON to be deserialized to.

using System.Runtime.Serialization;

namespace Milkshake.Integration.Google
{
	/// Defines a response from one of Google's AJAX APIs.
	/// The type of object, being returned.
	[DataContract]
	public class GoogleAjaxResponse<T>
	{
		///
		/// Gets or sets the response data.
		///
		///
		/// The responseData from Google AJAX API Call
		///
		/// The response data.
		[DataMember(Name = "responseData", Order = 0)]
		public T ResponseData { get; set; }
	}
}

To deserialize the Translation specific JSON, I use the TranslationResponse class:

using System.Net;
using System.Runtime.Serialization;

namespace Milkshake.Integration.Google.Translate
{
	/// Defines a response from the Google AJAX Translate API.
	[DataContract]
	public class TranslationResponse
	{
		/// Initializes a new instance of the  class.
		public TranslationResponse()
		{
			this.ResponseStatus = HttpStatusCode.OK;
		}

		/// Gets or sets the translated text.
		/// The translated text.
		[DataMember(Name = "translatedText", Order = 0)]
		public string TranslatedText { get; set; }

		/// Gets or sets the response details.
		/// The response details.
		[DataMember(Name = "responseDetails", Order = 1)]
		public object ResponseDetails { get; set; }

		/// Gets or sets the response status.
		/// The response status.
		[DataMember(Name = "responseStatus", Order = 2)]
		public HttpStatusCode ResponseStatus { get; set; }
	}
}

Calling the Google AJAX Translate API

To make the actual call, we can use the HttpWebRequest and HttpWebResponse classes.

using System;
using System.Globalization;
using System.IO;
using System.Net;
using System.Web;
using System.Web.Script.Serialization;

namespace Milkshake.Integration.Google.Translate
{
	/// An API Client for the Google AJAX Translate API.
	public class TranslateApi
	{
		/// The JavaScript serializer
		private JavaScriptSerializer _Serializer = new JavaScriptSerializer();

		/// Translates the text.
		public string TranslateText(string inputText, string sourceLanguage, string destinationLanguage, string referrer, string apiKey)
		{
			string requestUrl = string.Format("http://ajax.googleapis.com/ajax/services/language/translate?v=1.0&q={0}&langpair={1}|{2}&key={3}", HttpUtility.UrlEncode(inputText), sourceLanguage.ToLowerInvariant(), destinationLanguage.ToLowerInvariant(), apiKey);

			try
			{
				using (HttpClient http = new HttpClient(requestUrl))
				{
					http.AddReferrer(referrer);
					http.ExecuteRequest();

					string responseJson = http.GetResponseString();

					GoogleAjaxResponse<TranslationResponse> translation = this._Serializer.Deserialize<GoogleAjaxResponse<TranslationResponse>>(responseJson);

					if (translation != null && translation.ResponseData != null && translation.ResponseData.ResponseStatus == HttpStatusCode.OK)
					{
						return translation.ResponseData.TranslatedText;
					}
					else
					{
						return String.Empty;
					}
				}
			}
			catch
			{
				return String.Empty;
			}
		}
	}
}

The response JSON and translated text

Doing a simple test, I translate “Hello world” from English to Danish, and I can see that it works like a charm.

Professional translations - even via API!