thymeleaf - How to pass common data to every page in project

Question

spring-boot-starter-parent 2.4.1

spring-boot-starter-thymeleaf

I have a bunch of constants that I want to be accessible everywhere.

For example I have organized some constants:

public class Constants {
    public final static String LANG = "lang";
}

Here I have a param which I already use in two places: in LocaleResolver and in LocaleChangeInterceptor.

And I need on every page where I include this fragment:

<th:block th:fragment="top" !doctype html>
    <div>
        <a href="?lang=fr">French</a>
        <a href="?lang=en">Английский</a>
    </div>
</th:block>

As we can see, this hardcoded twice. I'd like to avoid such cases.

Is it possible somehow? If a class with static methods is not a good practice, I can use whatever you suggest. Even if such class is preferrable for me, any elegant solution would be highly appreciated.

question from:https://stackoverflow.com/questions/65840788/how-to-pass-common-data-to-every-page-in-project

Answer 1

You can access static variable in Thymeleaf expressions.

<th:block th:fragment="top" !doctype html>
    <div>
        <a th:href="|?${T(Constants).LANG}=fr|">French</a>
        <a th:href="|?${T(Constants).LANG}=en|">Английский</a>
    </div>
</th:block>

(Where Constants is the full path to your class)