javathymeleafisnullorempty

How to check null and empty condition using Thymeleaf in one single operation?

Is there any way to check both null and empty condition in Thymeleaf?

Approach 1

1) .variable1?.variable2?.variable3
2) variable!=null 
3) variable!=''

If we combine two conditions like (variable!='' And variable!=null) I am having issue when rendering.

I am trying following sample

${#strings.concat(#strings.concat('class ',variable1?.variable2), ' ', variable1?.variable2?.variable3)}

I also used containsKey as well but it is behaving differently.

Solution

  • In order to check null or empty string using thymeleaf expressions, Use this approach : --- 

    <div th:if= "${searchResults.results != null}">

    OR, this :-- 

    <div th:if= "${searchResults.results != ''}">

    Furthermore, you can check the empty or null object on your controller itself and then send the response on your thymeleaf-html page accordingly, like this :--
    1.) Your Controller :- 

     List ls = //some data from you DAO
    if(ls.isEmpty()){
         model.addAttribute("response","NoData");
      }else{
         model.addAttribute("response",ls);
     }

    2.) Then on your Thymleaf page :- - - 

    <th:block th:if="${response=='NoData'}"> No Data Found </th:block>

    PS - I've answered the same question here which helps the questioner hope it helps you as well :-- ThymeLeaf: Not Equal expression in th:if