java - Binding embedded List of objects on a Thymeleaf template for a POST request -

i developing grocery store list web application. 1 feature should (un)checking found/bought items on list. displaying values works fine. when check checkboxes on bought items , try post afterwards incomming @modelattribute in spring mvc controller null (except id).

i hope can me.

here classes:

public class purchaselist {  private long id; private list<purchaseitem> purchaseitemlist; private datetime purchasedate; private boolean done; }   public class purchaseitem {  private long id; private string purchaseitemname; private purchasecategory purchasecategory; private purchaselist purchaselist; private boolean found; } 

the controller:

@requestmapping(value="/{id}", method=requestmethod.post)   public string postpurchaselist(@pathvariable(value="id") long id, @modelattribute("purchaselist") purchaselist purchaselist, model model) {   list<purchaselist> notdonepurchaselist = purchaselistservice.getnotdonepurchaselist();   model.addattribute("notdonepurchases", notdonepurchaselist);   purchaselistservice.savepurchaselist(purchaselist);   return "purchaselist"; } 

the thymeleaf template

<form action="#" th:action="@{/purchaselist/{purchaselistid}/(purchaselistid=${purchaselist.id})}" th:object="${purchaselist}" method="post">       <table class="table table-bordered table-hover">         <thead>           <tr>             <td>found</td>             <td>item</td>             <td>category</td>           </tr>         </thead>         <tr th:each="item,status : ${purchaselist.purchaseitemlist}">           <td><input type="checkbox" th:checked="${item.found}" th:value="*{purchaseitemlist[__${status.index}__].found}" /></td>           <td th:text="${item.purchaseitemname}"></td>           <td th:text="${item.purchasecategory.categoryname}"></td>         </tr>       </table>       <input type="submit" value="submit" id="submit" />       </form> 

i know doesn't set other values (only found property). or problem?

best regards

edit:

1. initialized suggested arraylist purchaseitemlist. empty arraylist returned controller.

initialize purchaseitemlist in purchaselist class. public class purchaselist { private long id; private list<purchaseitem> purchaseitemlist=new arraylist<>(); private datetime purchasedate; private boolean done; }

give input field id this.

<td><input type="checkbox" th:checked="${item.found}" th:value="* {purchaseitemlist[__${status.index}__].found}" th:id='purchaselist.purchaseitemlist[__${status.index}__].found'/></td>