Google Script to interact with MailChimp API v3.0

MailChimpExample.gs

var API_KEY = 'XXXXXXX';
var API_USER = 'anystring';
var mc_list_id = 'XXXXX'; //List ID found in list settings
// Using adding members with custom signup forms in this example
var mc_base_url = 'https://us14.api.mailchimp.com/3.0/lists/' + mc_list_id + '/members';
//var mc_send = 'https://us14.api.mailchimp.com/3.0/automations/XXXX/emails/XXXXX/queue';

/** 
 * Used to convert email to MD5 hash to allow auto update of user information with MailChimp 3.0 API w/ PUT
 */
function sign(message){     
  message = message || "thisisteststring";
  var signature = Utilities.computeDigest(
                       Utilities.DigestAlgorithm.MD5,
                       message,
                       Utilities.Charset.US_ASCII);
  Logger.log(signature);
  var signatureStr = '';
    for (i = 0; i < signature.length; i++) {
      var byte = signature[i];
      if (byte < 0)
        byte += 256;
      var byteStr = byte.toString(16);
      // Ensure we have 2 chars in our byte, pad with 0
      if (byteStr.length == 1) byteStr = '0'+byteStr;
      signatureStr += byteStr;
    }   
  Logger.log(signatureStr);
  return signatureStr;
}

/**
 * Uses the MailChimp API to add a subscriber to a list.
 */
function sendToMailChimp_( em, src ) {
  // format to add any custom merge tags, here i'm just pushing the source
  var user = {
    "SRC" : src
  };

  var payload = {
    "merge_fields" : user,
    "email_address": em,
    "status" : "subscribed",
    //"update_existing" : false // left the update_existing on this way existing emails 
  };
  
  var headers = {
    "content-type" : "application/json",
    "Authorization" : " Basic " + Utilities.base64Encode(API_USER + ":" + API_KEY)
  };
  var options = {
    "method": "put",
    "headers" : headers,
    "payload": JSON.stringify( payload ),
    "followRedirects" : true,
    "muteHttpExceptions": true,
  };
  
  Logger.log(mc_base_url);
  Logger.log( options );
  //var options = JSON.stringify( options ) );
  var emailHash = sign( em ); //to use PUT command to auto-update existing subscribers
  var response = UrlFetchApp.fetch(mc_base_url +"/"+emailHash , options );
  if( response.getResponseCode() == 200 ) {
    console.info( "SUCCESS to PROD for " + em );
  } else {
    console.log(response);
  }
  
}

/**
 * Trigger function. Based on Google Script tutorial.
 * @param {Object} e The event parameter for form submission to a spreadsheet;
 *     see https://developers.google.com/apps-script/understanding_events
 */
function onFormSubmit(e) {
  Logger.log( "hit the function" );
  var email = e.namedValues['Email'][0];
  var source = "EXAMPLE";
  sendToMailChimp_( email, source ); //set initial person with no refby
}

/**
 * Main function. Creates onFormSubmit trigger.
 */
function myFunction(){
  var sheet = SpreadsheetApp.getActive();
  var a = ScriptApp.newTrigger("onFormSubmit");
  var b = a.forSpreadsheet(sheet);
  var c = b.onFormSubmit();
  var d = c.create();
}

Hey, Thanks for posting. This works perfectly to add a subscriber. However if I want to update a member or change the status to unsubscribe.

I get the following error response: "example@example.com is already a list member. Use PUT to insert or update list members."

And I'm using the method "put" as in your script.

Any suggestions?

Thanks in advance.

Really nice!
Wondering if I want to send a single email through mailchimp,... how can I add a subscriber to an automation with a dynamic text?

Like could you expand it with Transactional email in Mailchimp.
https://us8.api.mailchimp.com/3.0/automations/AUTOMATIONCODE/emails/EMAILINAUTOMATIONCODE/queue

Hi! I'm writing one more time.

Your code works perfectly, but I am struggling to make it work for a onEdit instead of onFormSubmit.

Could you please assist?

Would really really appreciate it.