Reference a variable on HTML pages across Java Web Application

Question

I'm using Spring in a Java Web Application with Thymeleaf on standard HTML pages (not JSP). I have forms on several pages with several text inputs. I would like to reference some variable for maxlength on the text inputs. For example:

Current:

<input id='name' type='text' maxlength='20' />

Goal:

<input id='name' type='text' maxlength='${nameMaxlength}' />

I would prefer to put these in a file somewhere that my Java code can access, so that the client-side and server-side validation can reference the same values. Are there any best practices for this sort of functionality?

Answer 1

If you are using Thymeleaf with the Spring dialect you could do the following:

package somepackage;

public final class WebConsts {

   public static final int MAX_LENGTH = 20;

   private WebConsts(){}
}

<input id="name" type="text" th:maxlength="${T(somepackage.WebConsts).MAX_LENGTH}" />

The expression in maxlength is a standard Spring EL expression

Answer 2

In Fuwesta I used a lot of tricks to reduce such duplication of information. My standard approach for this is to put the information into MessageSource. It's pretty easy and you have a nice access via #{constant.nameMaxLength}. Another approach would be to put this information always into the model.