Google Apps Script で multipart/form-data の HTTP リクエストを送信する

SendMultipartFormFromGAS.js

function request() {

  var parts = [];
  parts.push({name: "processModelInfoId", value: 1});
  parts.push({name: "nodeNumber", value: 1});
  parts.push({name: "key", value: "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"});
  parts.push({name: "title", value: "件名をここに"});
  parts.push({name: "data[0].upload", value: "ファイル本文をここに", filename: "ファイル名.csv", contentType: "text/csv; charset=UTF-8"});
  
  var boundary = "boundaryboundaryboundaryboundary";
  var payload = "";
  if (parts.length > 0) {
    for (var i=0; i<parts.length; i++) {
      payload += "--" + boundary + "\r\n";
      if (parts[i].filename !== undefined) {
        payload += "Content-Disposition: form-data; name=\"" + parts[i].name + "\"; filename=\"" + parts[i].filename + "\"\r\n";
        payload += "Content-Type: " + parts[i].contentType + "\r\n";
        payload += "\r\n"
        payload += parts[i].value + "\r\n";
      } else {
        payload += "Content-Disposition: form-data; name=\"" + parts[i].name + "\"\r\n";
        payload += "\r\n"
        payload += parts[i].value + "\r\n";
      }
    }
    payload += "--" + boundary + "--\r\n"
  }
  
   var options = {
     "method" : "post",
     "contentType" : "multipart/form-data, boundary=" + boundary,
     "payload" : payload
   };
  
  UrlFetchApp.fetch("https://YYYYYYYYY.questetra.net/System/Event/MessageStart/start", options);

}

Very useful script, thanks!