google script use html service in gmail addon

Question

I've try to create simple form in gmail addon,

how to use html service

The below code,i have tried,

function buildAddOn(e) {
  var accessToken = e.messageMetadata.accessToken;
  GmailApp.setCurrentMessageAccessToken(accessToken);
  var test_card = doGet()
  cards.push(test_card);
  return cards;
}
function doGet() {
   return HtmlService.createHtmlOutput('<b>Hello, world!</b>');
 }

Thanks in advance

Answer 1

I understood that you want to use HTML at Gmail add-on. If my understanding is correct, how about these sample scripts?

Sample script 1 :

function buildAddOn() {
  var html = HtmlService.createTemplate('<b>Hello, world!</b>').evaluate().getContent();
  return CardService.newCardBuilder()
  .setHeader(CardService.newCardHeader().setTitle('sample'))
  .addSection(CardService.newCardSection().addWidget(CardService.newKeyValue().setContent(html)))
  .build();
}

Sample script 2 :

function buildAddOn() {
  var html = HtmlService.createTemplateFromFile("index").evaluate().getContent();
  return CardService.newCardBuilder()
  .setHeader(CardService.newCardHeader().setTitle('sample'))
  .addSection(CardService.newCardSection().addWidget(CardService.newKeyValue().setContent(html)))
  .build();
}

<b>Hello, world!</b>

Result :

Note :

• As a sample, Manifests was used from Quickstart.
• This is a very simple script. So please modify it for your environment.

If I misunderstand your question, I'm sorry.