提交具有多个commandName或Modellattribute的表单

Question

I wanna save a comment by submitting the form below:

<form:form method="post" action="postNewComment.html"  commandName="comment"  >
    <table>
        <tr>
            <td><form:label path="comment">
                    COMMENT
                </form:label></td>
            <td><form:input path="comment" /></td>
        </tr>                       
        <tr>
            <td colspan="2"><input type="submit"
                value="WRITE" /></td>
        </tr>
    </table>
</form:form>

in the simplest case the addNewComment() method gets called in the Controller, and everything is fine.

@RequestMapping(value = "/postNewComment", method = RequestMethod.POST)
    public ModelAndView addNewComment(@ModelAttribute("comment") Comment comment, BindingResult result) {
        commentService.addComment(comment);
        Map<String, Object> model = new HashMap<String, Object>();
        model.put("COMMENTS", commentService.getComments());
        return new ModelAndView("showAllComments", model);
    }

Everything is fine as long as I don't want to record which User made the Comment. However if the Comment class contains a field which is a User like this

@Entity
@Table(name = "comments")
public class Comment {

    // more fields...

    @ManyToOne
    @JoinColumn(name = "user_id")
    private User user;

   //getters-setters

and I have a valid User object in the .jsp file like this:

<c:if test="${!empty LOGGED_IN_USER}">
        <spring:message code="label.welcome" /> ${LOGGED_IN_USER.userName}
    </c:if>

How can I send NOT only the Comment, but the LOGGED_IN_USER as well by submitting the above mentioned form?

The "solution" below is not gonna work: (crashes with org.apache.jasper.JasperException)

<form:form method="post" action="postNewComment.html"  commandName="comment"  >
        <table>
            <tr>
                <td><form:label path="comment">
                        COMMENT
                    </form:label></td>
                <td><form:input path="comment" /></td>
            </tr>
            <tr>
                <td><form:label path="user">
                        USER
                    </form:label></td>
                <td><form:input path=" ${LOGGED_IN_USER}" /></td>
            </tr>   

            <tr>
                <td colspan="2"><input type="submit"
                    value="WRITE" /></td>
            </tr>
        </table>
    </form:form>

Answer 1

I am assuming your logged in user must in the session right - if so you can simply set the user into your comment inside your controller -

comment.setUser(sessionUser)

Or you can set the sessionUser when presenting your comment object, if so you can simply do:

<form:hidden path="user"/>