How to prompt user of container-bound script to "review permissions"

Question

As far as I've read google app script is supposed to show you a prompt to review permissions automatically if you have not authorized your app yet. However this is not happening and I also cannot find a way to manually trigger such a prompt that can be used within onOpen(e).

What I would like to achieve is my app prompting users to review permissions when they have not authorized the app yet.

What I have tried:

• Letting GAS automatically detect used scopes.
• Manually setting scopes using the appscript.json file.
• Using Ui.showModalDialog() and ScriptApp.getAuthorizationInfo().getAuthorizationUrl() to manually guide the user to permissions. However, this results in the error:

Google Apps Script: Exception: You do not have permission to call Ui.showModalDialog. 
Required permissions: https://www.googleapis.com/auth/script.container.ui

Answer 1

Issue:

You are using a simple trigger (onOpen). Simple triggers cannot access services that require authorization.

Solution:

Install your trigger, either manually, following these steps, or programmatically, executing this:

function installTrigger() {
  ScriptApp.newTrigger("yourOnOpenFunction") // Don't call it onOpen
           .forSpreadsheet(SpreadsheetApp.getActive())
           .onOpen()
           .create();
}

The authorization is given when installing the trigger.

Note:

The installed trigger will run under the account who installed it. Therefore, this is not a good approach if the actions made by the trigger depend on who is executing it, and I'd suggest displaying the dialog through other means, like clicking a button, or similar.

Reference:

• Simple triggers: Restrictions