[Redmine] How to get mail notification value in user page

Problem
I am trying to get admin value from the redmine user object. 
But I cannot get admin value, no matter using Java API or Rest API.
It can only retrieve very limited information:



How-To
We can make good use of jsoup to parse html page and get value from the specific html element.

Firstly, checking the drop down list element in html. 


Secondly, using jsoup to parse HTML

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String url = "http://192.168.0.1/users/" + userId + "/edit"; Document document = Jsoup.connect(url).get(); Elements mailNotificationElements = document.select("[name=user[mail_notification]]").select("option"); for (Element element : mailNotificationElements) { if ("selected".equals(element.attr("selected"))) { log.debug("the mail_notification value = " + element.val()); break; } }

Reference
[1] https://jsoup.org/