javascript - How can I pass a parameter to a time-based Google App Script trigger?

Question

In my script, I am reading data from a Spreadsheet and creating a time based trigger to make a POST request with some of that data at a specific time.

The problem is, I can't find any way to pass the data to the function that is called by the trigger. All that the Google App Script doc offers is the ability to name the function to call, but no way to pass it parameters.

 var triggerDay = new Date(2012, 11, 1);
 ScriptApp.newTrigger("makePostRequest")
   .timeBased()
   .at(triggerDay)
   .create();

Does anyone know how I can pass makePostRequest parameters so the function will execute with the needed data?

Answer 1

This is possible but requires multiple steps. The most important thing here are event objects (mentioned by @St3ph).

var RECURRING_KEY = "recurring";
var ARGUMENTS_KEY = "arguments";

/**
 * Sets up the arguments for the given trigger.
 *
 * @param {Trigger} trigger - The trigger for which the arguments are set up
 * @param {*} functionArguments - The arguments which should be stored for the function call
 * @param {boolean} recurring - Whether the trigger is recurring; if not the 
 *   arguments and the trigger are removed once it called the function
 */
function setupTriggerArguments(trigger, functionArguments, recurring) {
  var triggerUid = trigger.getUniqueId();
  var triggerData = {};
  triggerData[RECURRING_KEY] = recurring;
  triggerData[ARGUMENTS_KEY] = functionArguments;

  PropertiesService.getScriptProperties().setProperty(triggerUid, JSON.stringify(triggerData));
}

/**
 * Function which should be called when a trigger runs a function. Returns the stored arguments 
 * and deletes the properties entry and trigger if it is not recurring.
 *
 * @param {string} triggerUid - The trigger id
 * @return {*} - The arguments stored for this trigger
 */
function handleTriggered(triggerUid) {
  var scriptProperties = PropertiesService.getScriptProperties();
  var triggerData = JSON.parse(scriptProperties.getProperty(triggerUid));

  if (!triggerData[RECURRING_KEY]) {
    deleteTriggerByUid(triggerUid);
  }

  return triggerData[ARGUMENTS_KEY];
}

/**
 * Deletes trigger arguments of the trigger with the given id.
 *
 * @param {string} triggerUid - The trigger id
 */
function deleteTriggerArguments(triggerUid) {
  PropertiesService.getScriptProperties().deleteProperty(triggerUid);
}

/**
 * Deletes a trigger with the given id and its arguments.
 * When no project trigger with the id was found only an error is 
 * logged and the function continues trying to delete the arguments.
 * 
 * @param {string} triggerUid - The trigger id
 */
function deleteTriggerByUid(triggerUid) {
  if (!ScriptApp.getProjectTriggers().some(function (trigger) {
    if (trigger.getUniqueId() === triggerUid) {
      ScriptApp.deleteTrigger(trigger);
      return true;
    }

    return false;
  })) {
    console.error("Could not find trigger with id '%s'", triggerUid);
  }

  deleteTriggerArguments(triggerUid);
}

/**
 * Deletes a trigger and its arguments.
 * 
 * @param {Trigger} trigger - The trigger
 */
function deleteTrigger(trigger) {
  ScriptApp.deleteTrigger(trigger);
  deleteTriggerArguments(trigger.getUniqueId());
}

function example() {
  var trigger = ScriptApp.newTrigger("exampleTriggerFunction").timeBased()
    .after(5 * 1000)
    .create();

  setupTriggerArguments(trigger, ["a", "b", "c"], false);
}

function exampleTriggerFunction(event) {
  var functionArguments = handleTriggered(event.triggerUid);
  console.info("Function arguments: %s", functionArguments);
}

In case you are using the script properties for other values as well you might have to nest the trigger values.

Additionally you might have to use the script lock to prevent concurrent modification of the script properties.