Spring Thymeleaf th:selected on EnumList with multiple selection - spring

Question

I have this enum
enum Types{
A, B
}
I have a form class
public class MyForm {
private Types[] types;
//getter setters
}
here is my form with select
<form th:action="${#httpServletRequest.requestURI}" th:object="${myForm}" method="POST" id="form">
<select name="types" multiple="" id="testSelect"
th:each="type : ${T(com.test.Types).values()}"
th:value="${type}"
th:text="${type}"
th:selected="*{types != null AND #arrays.contains(types, type)}"
>
</select>
</form>
here is the error i am getting.
Property or field 'type' cannot be found on object of type 'com.test.MyForm' - maybe not public or not valid?

Answer 1

First, I believe you have a typo, it should be type != and not types !=. Also, you are using * in your selected, instead of $. Also, I believe you are using #list.contains() of Thymeleaf in a way that shouldn't work. You should use the whole function, just like this #list.contains(types, type). One last thing, the selected, value and text tags should should go in the option element, not the select. In the end your code should look like the following one.
<select name="types" multiple="" id="testSelect">
<option th:each="type : ${T(com.test.Types).values()}"
th:value="${type}" th:text="${type}"
th:selected="${types != null AND #arrays.contains(types, type)}">
</option>
</select>
One last thing, I am not sure where did the variable types came from, I am assuming you initialized it somewhere.

Answer 2

The best would be to change your form backing bean to have some collection of your enumerations, instead of array such as:
public class MyForm {
private List<Types> types = new ArrayList<Types>();
//getter setters
}
Then before you render the form, you can just fill this array with types, which you want to be preselected in the controller just by adding them to the list.
Then should be able to simply skip th:selected logic...
<select th:field="*{types}" multiple="multiple" id="testSelect">
<option th:each="type : ${T(com.test.Types).values()}"
th:value="${type}" th:text="${type}">
</option>
</select>
Thymeleaf will do the magic for you ;-)