html - Having a form under a For-Each cycle in Thymeleaf -

i new in spring boot , have problem thymeleaf. want use html form under each cycle, receive exception.

this code:

            <tr th:each="item : ${users}">             <td th:text="${item.getfirstname()}">first name</td>             <td th:text="${item.getlastname()}">last name</td>             <td th:text="${item.getemailaddress()}">email address</td>             <td th:text="${item.getdateofbirth()}">date of birth</td>             <!--<td><a th:href="${'/user/edit/' + user.id}">edit</a></td> -->             <td>edit</td>             <td>                 <form th:object="${item}" th:action="@{/delete}" method="post">                     <input type="hidden" th:field="*{firstname}"/>                     <input type="hidden" th:field="*{lastname}"/>                     <input type="hidden" th:field="*{emailaddress}"/>                     <input type="hidden" th:field="*{dateofbirth}"/>                     <input type="submit" value="delete"/>                 </form>             </td>         </tr> 

and exception receive:

[thymeleaf][http-nio-8080-exec-1] exception processing template "users": error during execution of processor 'org.thymeleaf.spring4.processor.attr.springinputgeneralfieldattrprocessor' (users:31) 

can tell me doing wrong?

thank in advance!!!

i use thymeleaf view engine in spring boot app.following example code might idea it.

user model

@entity public class user {      @id     @generatedvalue(strategy = generationtype.identity)     @column(name="id", nullable = false )     private long id;       @column(name="user_name" )     private string username;       @email(message="email not valid")     @column(name="email",nullable=false)     private string email;      public long getid() {         return id;     }      public void setid(long id) {         this.id = id;     }      public string getusername() {         return username;     }      public void setusername(string username) {         this.username = username;     }  } 

user controller

model.addattribute("users", userservice.getallusers()); 

user view

<tr th:each="user : ${users}">     <td th:text="${user.id}"></td>     <td th:text="${user.email}"></td>     <td th:text="${user.username}"></td> </tr>