Custom function for Google Spreadsheets App Scripts for querying NYSaves.org prices

NYSaves.gs

var _ = Underscore.load();


var NYSaves = {};

NYSaves.currentPriceUrlBase = 'https://www.nysaves.org/nytpl/fund/details.cs?fundId=';
NYSaves.historyUrl = 'https://www.nysaves.org/nytpl/fund/priceHistorySearch.cs';


/**
 * NOTE: NySaves will not return prices for weekend dates.
 * @private
 */
function _getPriceForRange(tickerId, startDate, endDate) {
  // POST data: fundId=1003014&startDate=05%2F03%2F2016&endDate=05%2F03%2F2016

  var response = _fetchUrlWithCookies(NYSaves.historyUrl, {
    method: 'post',
    payload: {
      'fundId': tickerId + "",
      'startDate': _dateToStringNySaves(startDate),
      'endDate': _dateToStringNySaves(endDate)
    }
  });
  
  var textContent = response.getContentText();
  
  Logger.log('Found textContent %s', textContent); 
  
  // And return the first price.
  var found = textContent.match(/\$\d+.\d+/g);
 
  // Strip $ symbol 
  found = _.map(found, function(price) {
    return price.replace('$','');
  });
  
  Logger.log('Found prices %s', found); 
  
  return found;  
}


/** 
 * Looks five days back from the supplied date and returns the
 * latest price found. This is so that if there is a holiday or weekend, we
 * still return a price (albeit potentially stale) for that date.
 */
NYSaves.getLatestPriceForDate = function(tickerId, date) {
  return _.last(_getPriceForRange(tickerId, Util.getDaysAgo(date, 5), date));
}


/**
 * @private
 */
function _dateToStringNySaves(date) {
  var mon = Util.padDate(date.getMonth()+1);
  var day = Util.padDate(date.getDate());  
  return mon + '/' + day + '/' + date.getYear();
}


/**
 * Gets current price of NYSaves.org ticker
 * @private
 */
function _getNySavesPrice(tickerId) {
  var url = NYSaves.currentPriceUrlBase + tickerId;

  // We make another request to get the page content with the cookie detection cookie.
  var response = _fetchUrlWithCookies(url, {followRedirects: false});
  
  var textContent =  response.getContentText();
  
  // And return the first price, stripping $ symbol.
  return textContent.match(/\$\d+.\d+/)[0].replace('$','');
}

/**
 * Makes two requests to a URL. The first request is to check for a cookie
 * and then store it. The second request is to the same URL with that cookie
 * in the header. This is a workaround for sites (like NYSaves.org) with 
 * cookie detection.
 * @private
 */
function _fetchUrlWithCookies(url, data) {
  // We need to make an initial request because NYSaves.org has a dumb cookie
  // detection system.
  var initialResponse = UrlFetchApp.fetch(url, data);

  var headers = initialResponse.getHeaders();
  
  var cookies = headers['Set-Cookie'];
  
  data['headers'] = {Cookie: cookies};

  // We make another request to get the page content with the cookie detection cookie.
  return UrlFetchApp.fetch(url, data);
}


/**
 * Returns the latest price of a NY Saves ticker ID.
 *
 * @param {String} tickerId NYSaves.org ticker ID
 * @customfunction
 */
function NYSAVES_PRICE(tickerId) {
  return _getNySavesPrice(tickerId);
}