Spring MVC Form - Long and String value. The request sent by the client was syntactically incorrect - spring

Question

Simply example, check it
Entity (USER, MOBILEPHONE)
#Entity
#Table(name = "USER")
public class User {
private Long id
private String name;
private Set<Mobilephone> mobilephones= new HashSet<mobilephones>(0);
public User(Long id)
this.id = id
}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
public Long getId() {
return this.id;
}
public void setId(long id) {
this.id = id;
}
//getter and setter for name
#OneToMany(fetch = FetchType.LAZY, mappedBy = "user")
public Set<Mobilephone> getMobilephones() {
return this.mobilephones;
}
public void setMobilephones(Set<Mobilephone> mobilephones) {
this.mobilephones= mobilephones;
}
#Entity
#Table(name = "MOBILEPHONE")
public class Mobilephone {
private Long id
private Long number;
private User user
public MobilePhone(Long id)
this.id = id
}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
public Long getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
//getter and setter for number
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "USERID", nullable = false)
public User getUser() {
return this.user;
}
public void setUser(User user) {
this.user= user;
}
Webpage
<form:form modelAttribute="mobilephoneAttribute" action="url" method="post">
<form:input path="mobilephone"/>
<form:select path="user">
<c:forEach items="${userlist}" var="user">
<form:option value="${user.id}" label="${user.telephone" />
</c:forEach>
</form:select>
<input type="submit"/>
</form:form>
Whats happening.
After submit i get this error:
The request sent by the client was syntactically incorrect.
If I change my User: "Long id" to "String id" (and also methods) the problem disappears.
I thought at the beginning, spring has a problem with the convert Long to String?
But probably not, because we have a number where Long is saved with no problems.
Someone knows the problem?

Answer 1

try using
<form:select path="user.id">
<c:forEach items="${userlist}" var="user">
<form:option value="${user.id}" label="${user.telephone" />
</c:forEach>
</form:select>