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

问题

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!

回答1:

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:

• Properties Service
• String.prototype.substring()
• String.prototype.concat()

I hope this is of any help.

来源：https://stackoverflow.com/questions/60094336/gmail-add-on-pass-parameters-to-function-triggered-by-card-action