java - How can I pass a hidden value from my Thymeleaf template to a controller(Spring Boot)? -

i'm running spring boot project , i'm trying pass id or object using post method keep returning null user. make user available when summary page created(post method hit separate form) user can added summary object.

i believe there might way pass id anchor link?

this html:

        <div >         <span th:text="${user.firstname}"></span> summary page             <span th:text="${user.emailaddress}"></span>             <form id="add" th:action="@{/addsummary}" method="post">                 <input id="userid" name="${user.userid}" type="hidden" value="${userid}"/>           <!-- <input id="userid" name="${user}" type="hidden" value="${user}"/> -->                 <button type="submit" value="save">add summary</button>             </form>         </div> <!-- way pass id? --> <!--<a href="createsummary.html?user.id">addsummary</a>--> 

the controller:

    @requestmapping(value ="/addsummary", method = requestmethod.post) public modelandview addsummary(user user) {      try{         modelandview model = new modelandview("views/createsummary");         system.out.println("======post summary method hit=====");     //    model.addobject("summary", new summary());         user nuser = userservice.findbyid(user.getuserid());         model.addobject("user", nuser);         system.out.println("user: " + nuser.getuserid());         return model;     }catch(exception ex){         system.out.println(ex.tostring());         throw ex;     } } 

any or suggestions appreciated! - thanks

first, core problem code try use thymeleaf expressions in non-thymeleaf attributes, not work expected. thymeleaf @ attributes starting th: (or data-th- if using html5 syntax).

for case use th:object , th:field:

<form id="add" th:action="@{/addsummary}" method="post" th:object="${user}">   <input id="userid" th:field="*{userid}" type="hidden"/>   <button type="submit" value="save">add summary</button> </form> 

reference: creating form in thymeleaf + spring tutorial.