Gmail Add-on pass parameters to function triggered by card action

Question

I'm building a Gmail add-on that creates a card with just one form button. Once clicked, I want the button to trigger a function that will send the open email's content to an external API.

So far, I have something like this:

function createCard(event) {
  var currentMessage = getCurrentMessage(event).getBody();
  var section = CardService.newCardSection();

  var submitForm = CardService.newAction()
    .setFunctionName('callAPI');

  var submitButton = CardService.newTextButton()
    .setText('Submit')
    .setOnClickAction(submitForm);

  section.addWidget(CardService.newButtonSet()
    .addButton(submitButton));

  var card = CardService.newCardBuilder()
    .setHeader(CardService.newCardHeader()
    .setTitle('Click this button'))
    .addSection(section)
    .build();

  return [card];
}

function callAPI(event) {
  var payload = { "msg": msg }; // msg is the parameter I need to get from the function call
  var options = {
        "method"  : "POST",
        "contentType": "application/json",
        "payload" : JSON.stringify(payload),
        "followRedirects" : true,
        "muteHttpExceptions": true
  };

  return UrlFetchApp.fetch('https://www.someAPI.com/api/endpoint', options);
}

How can I pass the currentMessage variable into the callAPI function? According to the documentation, the only parameter that we can get from an action function seems to be event that only has the form fields data. If there isn't a way to pass other parameters, is there a way for that function to get the context data of the message directly inside the function??

Thanks!

score 5 · Answer 1 · answered Aug 29 '21 at 18:20

I believe the proper way to pass the currentMessage content to the callAPI function would be to use the setParameters as described in this documentation

Your code would look like this:

var submitForm = CardService.newAction()
    .setFunctionName('callAPI')
    .setParameters({message: currentMessage});

In the callback, your would fetch the message by using something like:

function callAPI(event) {
    var payload = event.parameters.message; 
    ...

As a reminder, both the key (message) as the value (currentMessage) must be Strings.

Thanks for this! I couldn't find any other examples of how to read the parameters in the event handler. — Homr Zodyssey, Jun 30 '22 at 13:14

Iamblichus · Answer 2 · 2020-02-11T11:25:37.960

You can use Properties Service, which allows you to store strings as key-value pairs. The idea would be to store the value of currentMessage in a property in the function createCard, and then use it in callAPI.

First, to store the variable, you can add the following lines to createCard after declaring currentMessage:

var userProperties = PropertiesService.getUserProperties();
userProperties.setProperty("currentMessage", currentMessage);

Second, to retrieve this variable, add the following lines to callAPI:

var userProperties = PropertiesService.getUserProperties();
var msg = userProperties.getProperty("currentMessage");

Update:

In order to avoid the limit of characters for a single property, you could also split your message into as many properties as were necessary.

You would first have to split the message into an array via substring, and store each element of the array in a different property. You would have to add this to createCard, after declaring currentMessage:

var messageArray = [];
var i = 0;
var k = 5000; // Character limit for one property (change accordingly)
while (i < currentMessage.length) {
  var part = currentMessage.substring(i, i += k);
  messageArray.push(part); // Splitting string into an array of strings
}
var userProperties = PropertiesService.getUserProperties();
userProperties.deleteAllProperties(); // Delete old properties
for (var j = 0; j < messageArray.length; j++) { // Set a different property for each element in the array
  userProperties.setProperty('messagePart' + j, messageArray[j]);
}

Then, to retrieve the message body, you could first retrieve all the properties corresponding to the message, and then join all the values in a single string with concat. Add the following lines to callAPI:

var userProperties = PropertiesService.getUserProperties();
var keys = userProperties.getKeys(); // Get all property keys
var j = 0;
var currentMessage = "";
do {
  var part = userProperties.getProperty('messagePart' + j);
  currentMessage = currentMessage.concat(part); // Concat each property value to a single string.
  j++;    
} while (keys.indexOf('messagePart' + j) !== -1); // Check if property key exists

Reference:

I hope this is of any help.

Thanks @iamblichus! The only problem with this solution is that there's a limit on character count for the value passed to setProperty, so I can't use it to store the message body. — uckc, Feb 07 '20 at 23:25
@uckc in that case, you could split your body into several properties. There is a limit to this too, but it's much higher. And this could be easily automated. If you think this could be a valid workaround, I'll update my answer with the corresponding code. — Iamblichus, Feb 10 '20 at 15:21
@uckc I updated my answer. This way, I think you can avoid the character limit issue. Please tell me if that works for you. — Iamblichus, Feb 11 '20 at 11:27
I tried splitting the string into multiple properties but it crashed the add-on and returned a timeout. In the end, I took a different approach and used Gmail's API to take care of forwarding the content of the email rather than through the API. — uckc, Apr 25 '20 at 23:05

Gmail Add-on pass parameters to function triggered by card action

2 Answers2

Update:

Reference:

Linked