如何使用百里香叶收集物体？

Question

PROBLEM:When I submitted the form, the server report:"Failed to convert property value of type java.lang.String[] to required type java.util.List for property ingredients".

MY GUESS:I think the problem is that collected property ingredients is String. I use thymeleaf as frontend.

QUESTION:How can I collect ingredients using thymeleaf?

DOMAIN Taco:
private String name;
private List<Ingredient> ingredients;


DOMAIN Ingredient: 
private final String id;
private final String name;
private final Type type;
public static enum Type{
    WRAP, PROTEIN, VEGGIES, CHEESE, SAUCE
}

CONTROLLER:
import taco.Ingredient.Type;

//method to show design
public String showDesign(Model model) {
List<Ingredient> ingredients = new ArrayList<>();
ingredientRepo.findAll().forEach(i-> ingredients.add(i));

Type[] types = Type.values();
for(Type type:types) {
    model.addAttribute(type.toString().toLowerCase(),filterByType(ingr
        edients, type));
}

model.addAttribute("taco", new Taco());

    return "design";
}

//method that is used to handle the post request
@PostMapping
public String processDesignForm(Taco taco) {
    log.info("process taco: "+taco);

    return "redirect:/orders/current";
}


DESIGN(use thymeleaf):
<form method="POST" th:object="${taco}">
    <div th:each="ingredient : ${wrap}">
        <input name="ingredients" type="checkbox" 
               th:value="${ingredient.id}" />
    </div>
</form>

Answer 1

You can do the following, get the ids selected (ingredients) as RequestParam

@PostMapping
public String processDesignForm(Taco taco, @RequestParam("ingredients") List<String> idIngredients) {
    log.info("process taco: "+taco);

    if(idIngredients != null){
        for(String id : idIngredients){
            ...//handle it
         } 
    }
...