Quickstart: Use the Translator Text API to translate a string using Go

In this quickstart, you'll learn how to translate a text string from English to Italian and German using Go and the Translator Text REST API.

This quickstart requires an Azure Cognitive Services account with a Translator Text resource. If you don't have an account, you can use the free trial to get a subscription key.

Prerequisites

This quickstart requires:

  • Go
  • An Azure subscription key for Translator Text

Create a project and import required modules

Create a new Go project using your favorite IDE or editor. Then copy this code snippet into your project in a file named translate-text.go.

package main

import (
    "bytes"
    "encoding/json"
    "fmt"
    "log"
    "net/http"
    "net/url"
    "os"
)

Create the main function

This sample will try to read your Translator Text subscription key from the environment variable TRANSLATOR_TEXT_KEY. If you're not familiar with environment variables, you can set subscriptionKey as a string and comment out the conditional statement.

Copy this code into your project:

func main() {
    /*
     * Read your subscription key from an env variable.
     * Please note: You can replace this code block with
     * var subscriptionKey = "YOUR_SUBSCRIPTION_KEY" if you don't
     * want to use env variables.
     */
    subscriptionKey := os.Getenv("TRANSLATOR_TEXT_KEY")
    if subscriptionKey == "" {
       log.Fatal("Environment variable TRANSLATOR_TEXT_KEY is not set.")
    }
    /*
     * This calls our translate function, which we'll
     * create in the next section. It takes a single argument,
     * the subscription key.
     */
    translate(subscriptionKey)
}

Create a function to translate text

Let's create a function to translate text. This function will take a single argument, your Translator Text subscription key.

func translate(subscriptionKey string) {
    /*  
     * In the next few sections, we'll add code to this
     * function to make a request and handle the response.
     */
}

Next, let's construct the URL. The URL is built using the Parse() and Query() methods. You'll notice that parameters are added with the Add() method. In this sample, you're translating from English to German and Italian: de and it.

Copy this code into the translate function.

// Build the request URL. See: https://golang.org/pkg/net/url/#example_URL_Parse
u, _ := url.Parse("https://api.cognitive.microsofttranslator.com/translate?api-version=3.0")
q := u.Query()
q.Add("to", "de")
q.Add("to", "it")
u.RawQuery = q.Encode()

Note

For more information about endpoints, routes, and request parameters, see Translator Text API 3.0: Translate.

Create a struct for your request body

Next, create an anonymous structure for the request body and encode it as JSON with json.Marshal(). Add this code to the translate function.

// Create an anonymous struct for your request body and encode it to JSON
body := []struct {
    Text string
}{
    {Text: "Hello, world!"},
}
b, _ := json.Marshal(body)

Build the request

Now that you've encoded the request body as JSON, you can build your POST request, and call the Translator Text API.

// Build the HTTP POST request
req, err := http.NewRequest("POST", u.String(), bytes.NewBuffer(b))
if err != nil {
    log.Fatal(err)
}
// Add required headers to the request
req.Header.Add("Ocp-Apim-Subscription-Key", subscriptionKey)
req.Header.Add("Content-Type", "application/json")

// Call the Translator Text API
res, err := http.DefaultClient.Do(req)
if err != nil {
    log.Fatal(err)
}

Handle and print the response

Add this code to the translate function to decode the JSON response, and then format and print the result.

// Decode the JSON response
var result interface{}
if err := json.NewDecoder(res.Body).Decode(&result); err != nil {
    log.Fatal(err)
}
// Format and print the response to terminal
prettyJSON, _ := json.MarshalIndent(result, "", "  ")
fmt.Printf("%s\n", prettyJSON)

Put it all together

That's it, you've put together a simple program that will call the Translator Text API and return a JSON response. Now it's time to run your program:

go run translate-text.go

If you'd like to compare your code against ours, the complete sample is available on GitHub.

Sample response

A successful response is returned in JSON as shown in the following example:

[
  {
    "detectedLanguage": {
      "language": "en",
      "score": 1.0
    },
    "translations": [
      {
        "text": "Hallo Welt!",
        "to": "de"
      },
      {
        "text": "Salve, mondo!",
        "to": "it"
      }
    ]
  }
]

Next steps

Explore Go packages for Cognitive Services APIs from the Azure SDK for Go on GitHub.

See also

Learn how to use the Translator Text API to: