MPESA Integration using GO (Using till number)

main.go

package main

import (
	"bytes"
	b64 "encoding/base64"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"time"
)

type SafaricomTransactionResponse struct {
	MerchantRequestID   *string `json:"MerchantRequestID"`
	CheckoutRequestID   *string `json:"CheckoutRequestID"`
	ResponseCode        *string `json:"ResponseCode"`
	ResponseDescription *string `json:"ResponseDescription"`
	CustomerMessage     *string `json:"CustomerMessage"`
}

type TransactionRequest struct {
	BusinessShortCode string `json:"BusinessShortCode"`
	Password          string `json:"Password"`
	Timestamp         string `json:"Timestamp"`
	TransactionType   string `json:"TransactionType"`
	Amount            string `json:"Amount"`
	PartyA            string `json:"PartyA"`
	PartyB            string `json:"PartyB"`
	PhoneNumber       string `json:"PhoneNumber"`
	CallBackURL       string `json:"CallBackURL"`
	AccountReference  string `json:"AccountReference"`
	TransactionDesc   string `json:"TransactionDesc"`
}

type AuthResponse struct {
	AccessToken string `json:"access_token"`
	ExpiresSec  string `json:"expires_in"`
}

func main() {
	httpClient := http.Client{Timeout: time.Duration(20) * time.Second}
	BusinessShortCode := "XXXXXX" //This is the head office number for your buy goods or the store number.
	PassKey := "your-key-comes-here" //Pass key from your daraja portal

  //Both those values can be captured from your app (daraja portal)
	ConsumerKey := "YOUR-CONSUMER-KEY"
	ConsumerSecret := "YOUR-CONSUMER-SECRET"

	Timestamp := time.Now().UTC().Format("20060102150405")
	TransactionType := "CustomerBuyGoodsOnline"
	Amount := "1" //Amount to charge

	Password := b64.StdEncoding.EncodeToString([]byte(fmt.Sprintf("%s%s%s", BusinessShortCode, PassKey, Timestamp)))

	transactionRequest := TransactionRequest{
		BusinessShortCode: BusinessShortCode,
		Password:          Password,
		Timestamp:         Timestamp,
		TransactionType:   TransactionType,
		Amount:            Amount,
		PartyA:            "2547xxxxxxxx", //contact to send the request to. (should be the same with PhoneNumber
		PartyB:            "xxxxxxx", //This is the till number
		PhoneNumber:       "2547xxxxxxxx", //contact to send the request to
		CallBackURL:       "https://2ffc-196-202-208-214.eu.ngrok.io/callback", //This is just a callback to test if the transaction is paid or not
		AccountReference:  "USER_UUID",
		TransactionDesc:   "Test Payment",
	}

	req, err := http.NewRequest("GET", "https://api.safaricom.co.ke/oauth/v1/generate?grant_type=client_credentials", nil)

	if err != nil {
		panic(err.Error())
	}

	authr := fmt.Sprintf("Basic %s", b64.StdEncoding.EncodeToString([]byte(fmt.Sprintf("%s%s%s", ConsumerKey, ":", ConsumerSecret))))

	req.Header.Add("Content-Type", "application/json")
	req.Header.Add("Authorization", authr)

	resp, err := httpClient.Do(req)

	if err != nil {
		panic(err.Error())
	}

	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		body, _ := ioutil.ReadAll(resp.Body)
		panic(string(body))
	}

	var authResponse AuthResponse

	err = json.NewDecoder(resp.Body).Decode(&authResponse)

	jsonByte, err := json.Marshal(transactionRequest)

	if err != nil {
		return
	}

	req, err = http.NewRequest("POST", "https://api.safaricom.co.ke/mpesa/stkpush/v1/processrequest", bytes.NewBuffer(jsonByte))

	if err != nil {
		panic(err.Error())
	}

	req.Header.Add("Content-Type", "application/json")
	req.Header.Add("Authorization", fmt.Sprintf("%s %s", "Bearer", authResponse.AccessToken))

	resp, err = httpClient.Do(req)

	if err != nil {
		panic(err.Error())
	}

	defer resp.Body.Close()

	var safTran SafaricomTransactionResponse

	body, err := ioutil.ReadAll(resp.Body)
  
	if err != nil {
		panic(err.Error())
	}
  
	err = json.Unmarshal(body, &safTran)

	fmt.Println(*safTran.CheckoutRequestID)
}