Thymeleaf: th:value - if property exists

Question

I want to create a hidden input field:

<input type="hidden" th:value="${map.version} name="version"/>

Problem:
version maybe a non existing attribute yet (I am not talking about null!).
Right now I am getting an Exception Property or field 'version' cannot be found on object

What I need:
If it does not exist, th:value statement maybe ignored or tag removed

CLARIFICATION:
map comes from Spring Controller in a handler-method:

@PostMapping("/new")
public String handleMapFormSubmit(
    @ModelAttribute("map") @Valid AddMapCommand command, BindingResult result ) {

    if ( result.hasErrors() ) {
        return "map-form";
    }

    // do some stuff

    return ".....";
}

Problem is that map (AddMapCommmand) in this handler-method does not contain the version attribute. In another handler-method (UpdateMapCommand) it does. The whole point is to reuse the map-form thymeleaf template in both scenarios which are almost similar.

is `version` a key to the map that you're adding? If so, take a look at http://stackoverflow.com/questions/28621301/how-to-use-map-getkey-in-thymeleaf-broadleaf-ecom — riddle_me_this, May 13 '17 at 16:55
yes it is. but it can exist or not exist. I will look at the link thanks. — Dachstein, May 13 '17 at 18:43
I have tried `${map['version']}`. It works, when the version is set but throws an Exception if not. — Dachstein, May 13 '17 at 18:53
well, ok then: http://stackoverflow.com/questions/22559367/how-to-check-for-that-map-is-containg-the-particular-key-using-thymleaf — riddle_me_this, May 14 '17 at 04:33
map in my case is not a map (HashMap) but a GameMap, a own domain type with attributes in it (one of them is version) — Dachstein, May 14 '17 at 10:13

score 1 · Accepted Answer · answered May 15 '17 at 03:51

1

You can try the instanceof operator to be used only for the object that contains the property:

<input type="hidden" 
 th:if="${map instanceof T(my.project.UpdateMapCommand)}" 
 th:value="${map.version} name="version">

For future reference, it is extremely confusing using a variable like map and not have the reader interpret it as a java.util.Map. You should change your map variable name to make it less confusing, or at least for the purpose of asking the question on StackOverflow.

answered May 15 '17 at 03:51

riddle_me_this

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that pointed me to the right direction. thanks. I agree for the map naming. I was just in a hurry. cheers anyways! – Dachstein May 15 '17 at 07:30
Is there anything in Thymeleaf like: object.hasAttribute('version') ? – Dachstein May 15 '17 at 14:40

Thymeleaf: th:value - if property exists

1 Answers1