helloworld.go - How to run GoLang Sample Code using the Hello World API and X-Pay-Token

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helloworld.go - How to run GoLang Sample Code using the Hello World API and X-Pay-Token

In this "How-to" guide we will show you how to run the “Hello World” project using Visa Hello World API and and API Key - Shared Secret Authentication. The Hello World API is a simple API for testing the connectivity with the Visa Network.

 

Important Links:

 

 

How to Create a Visa Developer Project

 

Before you are able to run the “Hello World” Project, you must create a Visa Developer Portal (VDP) project and get credentials. If you haven't registered yet just click on register here, fill out the account information, agree to the terms and conditions and click on receive emails. Once you have successfully activated your account, you will see your dashboard and you are ready to go.

 

 

java1.png

 

 

Once you are there, click on create your first project if this is your first project.  On the next page, you will be asked for details, such as project name, description and a list of APIs to choose from.

 

 

Java2.png

 

For this tutorial, we're going to select CyberSource Payments and click create project.

 

 

CyberSourcePaymentMethod.png

 

 

 

How to get Credentials

 

After creating your project, you will be redirected to the project summary page. You can obtain your project credentials by browsing the left side navigation menu of your project and click on “Credentials”.

 

 

Java4.png

 

What is required for the X-Pay-Token Authentication?

 

To be able to make an API call with X-Pay-Token Authentication, you need to have the following:

  1. Api Key
  2. Secret Key

CredentialsForXPayToken.png

 

How to run the GoLang Sample code of the “Hello World API” using GoLand

 

 

Next, we'll show you how to run the GoLang sample code of the “Hello World API” using GoLand. GoLand is a cross-platform IDE that provides consistent experience on the Windows, macOS, and Linux operating systems, and can be downloaded using below link:

 

https://www.jetbrains.com/go/download

 

In GoLand, a project helps you organize your source code, tests, libraries that you use, build instructions, and your personal settings in a single unit.

 

 

Step 1 - Launch GoLand

 

  • On the GoLand Welcome Screen, click Create New Project.

2020-11-15_13-52-05.png

 

 

Otherwise, from the main menu, select File | New | Project

 

Step 2 - In the New Project wizard, select Go from the list on the left, provide the project Location, Go SDK and click Create.

 

2020-11-15_13-53-29.png

 

 

 

 

Step 3 - Create a new Go file as Simple Application and named it “helloworld

 

2020-11-15_13-55-45.png

 

 

Step 4 - Copy the below sample code to the “helloworld.go” file

 

  • Install all the required dependencies when prompt.
  • Set the below parameters:

 

apiKey    = "<YOUR API KEY>"

secretKey = "<YOUR SHARED SECRET>"

 

 

/**
 * (c) Copyright 2018 - 2020 Visa. All Rights Reserved.**
 *
 * NOTICE: The software and accompanying information and documentation (together, the “Software”) remain the property of and are proprietary to Visa and its suppliers and affiliates. The Software remains protected by intellectual property rights and may be covered by U.S. and foreign patents or patent applications. The Software is licensed and not sold.*
 *
 *  By accessing the Software you are agreeing to Visa's terms of use (developer.visa.com/terms) and privacy policy (developer.visa.com/privacy).In addition, all permissible uses of the Software must be in support of Visa products, programs and services provided through the Visa Developer Program (VDP) platform only (developer.visa.com). **THE SOFTWARE AND ANY ASSOCIATED INFORMATION OR DOCUMENTATION IS PROVIDED ON AN “AS IS,” “AS AVAILABLE,” “WITH ALL FAULTS” BASIS WITHOUT WARRANTY OR  CONDITION OF ANY KIND. YOUR USE IS AT YOUR OWN RISK.** All brand names are the property of their respective owners, used for identification purposes only, and do not imply product endorsement or affiliation with Visa. Any links to third party sites are for your information only and equally  do not constitute a Visa endorsement. Visa has no insight into and control over third party content and code and disclaims all liability for any such components, including continued availability and functionality. Benefits depend on implementation details and business factors and coding steps shown are exemplary only and do not reflect all necessary elements for the described capabilities. Capabilities and features are subject to Visa’s terms and conditions and may require development,implementation and resources by you based on your business and operational details. Please refer to the specific API documentation for details on the requirements, eligibility and geographic availability.*
 *
 * This Software includes programs, concepts and details under continuing development by Visa. Any Visa features,functionality, implementation, branding, and schedules may be amended, updated or canceled at Visa’s discretion.The timing of widespread availability of programs and functionality is also subject to a number of factors outside Visa’s control,including but not limited to deployment of necessary infrastructure by issuers, acquirers, merchants and mobile device manufacturers.*
 *
 */

package main

import (
   "crypto/hmac"
   "crypto/sha256"
   "encoding/hex"
   "io/ioutil"
   "log"
   "net/http"
   "strconv"
   "time"
)

var (
   // THIS IS EXAMPLE ONLY how will apiKey and password look like
   // apiKey = "1WM2TT4IHPXC8DQ5I3CH21n1rEBGK-Eyv_oLdzE2VZpDqRn_U";
   // sharedSecret = "19JRVdej9";

   apiKey    = "<YOUR API KEY>"
   secretKey = "<YOUR SHARED SECRET>"
)

func generateXPay(secretKey string, resourcePath string, queryParams string, postBody string) string {
   timestamp := strconv.Itoa(int(time.Now().Unix()))
   preHashString := timestamp + resourcePath + queryParams + postBody
   h := hmac.New(sha256.New, []byte(secretKey))
   // Write Data to it
   h.Write([]byte(preHashString))
   // Get result and encode as hexadecimal string
   hashString := hex.EncodeToString(h.Sum(nil))
   return "xv2:" + timestamp + ":" + hashString
}

func main() {

   queryParams := "apiKey=" + apiKey
   xpay := generateXPay(secretKey, "helloworld", queryParams, "")
   client := &http.Client{}

   request, err := http.NewRequest(http.MethodGet, "https://sandbox.api.visa.com/vdp/helloworld?"+queryParams, nil)
   if err != nil {
      panic(err)
   }

   request.Header.Set("x-pay-token", xpay)
   resp, err := client.Do(request)

   if err != nil {
      panic(err)
   }

   defer resp.Body.Close()
   body, err := ioutil.ReadAll(resp.Body)
   log.Println("Response Status:", resp.Status)
   log.Println("Response Body:", string(body))

}

 

 

 

Step 5 - Compile Your Code 

 

  • Simply right click and run “go build helloworld….”

 

2020-11-15_13-56-52.png

 

 

Want more? Join the Visa Developer Community to get alerts on the latest tutorials, guides and new developer resources. Stay tuned for more in the series. 

 

Written by: @shameem@jmedlen, & @mprsic