Failed to convert property value of type 'java.lang.String' - spring

Question

What am I doing wrong here?
<select th:field="*{role}">
<option value="#" disabled="disabled" selected="selected">Role...</option>
<option th:each="r : ${roles}" th:value="${r}" th:text="${r.name}">Developer</option>
</select>
I am getting this error:
Field error in object 'collaborator' on field 'role': rejected value
[33]; codes
[typeMismatch.collaborator.role,typeMismatch.role,typeMismatch.com.imprender.instateam.model.Role,typeMismatch];
arguments
[org.springframework.context.support.DefaultMessageSourceResolvable:
codes [collaborator.role,role]; arguments []; default message [role]];
default message [*Failed to convert property value of type
'java.lang.String' to required type
'com.imprender.instateam.model.Role' for property 'role'*; nested
exception is java.lang.IllegalStateException: Cannot convert value of
type 'java.lang.String' to required type
'com.imprender.instateam.model.Role' for property 'role': no matching
editors or conversion strategy found]
It says:
**Failed to convert property value of type 'java.lang.String' to required type 'com.imprender.instateam.model.Role' for property
'role'**
but I don't understand where I am doing that.
I think I am not properly transmiting the value selected in the . I thought the object sent would be the one declared in the valueoption that gets selected, but obviously I got it wrong and can't find the way to do it properly.
The model:
package com.imprender.instateam.model;
import javax.persistence.*;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Pattern;
#Entity
public class Collaborator {
#Id
//Todo: check strategy
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#NotNull
#Pattern(regexp = "([A-Z][a-zA-Z]*\\s*)+")
private String name;
//Todo: check, do we want to create a new table to associate values?
#NotNull
#ManyToOne
private Role role;
public Collaborator() {
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Role getRole() {
return role;
}
public void setRole(Role role) {
this.role = role;
}
}

Answer 1

Your problem is that in your select says the field is a role, entity type Role, but in your options the value is an ID, some primitive value, then doesnt match. You can change to this
<select th:field="*{role.id}">
<option value="#" disabled = "disabled" selected="selected">Role...</option>
<option th:each="r : ${roles}" th:value="${r.id}" th:text="${r.name}">Developer</option>
</select>