Develop Reference

Invalid property 'projection' of bean class

Hi I need a little help with my code. I tried solutions online but I couldn't fix my bug. I working in java and spring with mysql and tymeleaf. My error is short:
Invalid property 'projection' of bean class [com.bakulic.CinemaTicketShop.model.dto.requests.CreateOrUpdateProjectionDTO]: Bean property 'projection' is not readable or has an invalid getter method: Does the return type of the getter match the parameter type of the setter?
And I found that my problem is in the html file createProjectionForm whitch I will put below as well as the entities and all that is needed. My projection entity has a relation to Hall and Movie and I'm not sure how to get attributes of Movie and Hall in my html. For the fiel I tried to put ${projection.hall.name} and ${projection.movie.movieName}. Zou will find it in the code.
Thank you in advance.
#Data
#Getter
#Setter
#NoArgsConstructor
#AllArgsConstructor
#Entity
#Table(name = "projections")
public class Projection {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private int projectionId;
#Column(name = "date")
private String date;
#Column(name = "startTime")
private String startTime;
#ManyToOne
#JoinColumn(name = "idHall")
private Hall hall;
#ManyToOne
#JoinColumn(name = "idMovie")
private Movie movie;
#OneToMany(fetch = FetchType.LAZY, mappedBy = "projection", cascade = CascadeType.ALL)
private List<Seat> seatList;
#OneToMany(fetch = FetchType.LAZY, mappedBy = "projection", cascade = CascadeType.ALL)
private List<Ticket> ticketList;
}
#Entity
#Table(name = "halls")
#Data
#Getter
#Setter
#NoArgsConstructor
#AllArgsConstructor
public class Hall {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private int hallId;
#Column(name = "name")
private String name;
#Column(name = "numberofseats")
private Integer numberOfSeats;
#Column(name = "description")
private String description;
#OneToMany(fetch = FetchType.LAZY, mappedBy = "hall", cascade = CascadeType.ALL)
private List<Projection> projectionList;
}
#Entity
#Table(name = "movies")
#Data
#Getter
#Setter
#NoArgsConstructor
#AllArgsConstructor
public class Movie {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private int movieId;
#Column(name = "name")
private String name;
#Column(name = "description")
private String description;
#Column (name = "length")
private String length;
#Column(name = "picture")
private String picture;
#OneToMany(fetch = FetchType.LAZY, mappedBy = "movie", cascade = CascadeType.ALL)
private List<Projection> projectionList;
}
#Data
public class ProjectionDTO implements Serializable {
private int id;
private String date;
private String startTime;
private List<Seat> seatList;
private List<Ticket> ticketList;
private Hall hall;
private Movie movie;
public ProjectionDTO(Projection projection){
if(projection != null){
this.id = projection.getProjectionId();
this.date = projection.getDate();
this.startTime = projection.getStartTime();
this.seatList = projection.getSeatList();
this.ticketList = projection.getTicketList();
this.hall = projection.getHall();
this.movie = projection.getMovie();
}
}
}
#Data
#NoArgsConstructor
#AllArgsConstructor
#Builder
public class CreateOrUpdateProjectionDTO implements Serializable {
private String date;
private String startTime;
private List<Seat> seatList;
//aditional info
private String name;
private String movieName;
}
/** create projection*/
public Projection createProjection(CreateOrUpdateProjectionDTO createProjectionDTO){
if(createProjectionDTO == null){
throw new InvalidDataException("Projection cannot be null");
}
timeValidator.checkTime(createProjectionDTO.getStartTime());
dateValidator.checkDate(createProjectionDTO.getDate());
Projection proj = new Projection();
proj.setDate(createProjectionDTO.getDate());
proj.setStartTime(createProjectionDTO.getStartTime());
Hall hall = proj.getHall();
if(hall == null){
hall = new Hall();
}
hall.setName(createProjectionDTO.getName());
Integer numOfSeats = hall.getNumberOfSeats();
Movie movie = proj.getMovie();
if(movie == null){
movie = new Movie();
}
movie.setName(createProjectionDTO.getMovieName());
List<Seat> list = createProjectionDTO.getSeatList();
for(int i=1; i<=numOfSeats; i++ ){
Seat seat = new Seat();
seat.setSeatNumber(i);
seat.setStatus("empty");
list.add(seat);
}
Projection projCreated = projectionRepository.save(proj);
log.info(String.format("Projection %s has been created.", proj.getProjectionId()));
return projCreated;
} The function is similar for update.
<
<!DOCTYPE html>
<html lang="en" xmlns:th="http://thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Create theater</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css"
integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm"
crossorigin="anonymous">
</head>
<body style="background-color:lightgrey;">
<nav class="navbar navbar-expand-lg navbar-light bg-light">
<img src="../pictures/cinemalogo.png" th:src="#{pictures/cinemalogo.png}" class = "center"alt="logo" width="120" height="100"/>
<ul class="navbar-nav">
<li class="nav-item">
<h1>Our cinema!</h1>
</li>
</ul>
<ul class="navbar-nav">
<li class="nav-item">
<a class="nav-link" href="/logout">Logout</a>
</li>
</ul>
</nav>
</nav>
<br>
<br>
<div class="container">
<div class="row">
<div class="col-md-6 col-md-offset-3">
<h1>Add projection</h1><br>
<form th:action="#{/projection}" method="post" th:object="${projection}">
<div class="form-group">
<label class="control-label" for="date"> Date </label>
<input id="date" class="form-control" th:field="*{date}"
required autofocus="autofocus" />
</div>
<div class="form-group">
<label class="control-label" for="startTime"> Start time</label> <input
id="startTime" class="form-control" th:field="*{startTime}" required
autofocus="autofocus" />
</div>
<div class="form-group">
<label class="control-label" for="hallName"> Hall name </label> <input
id="hallName" class="form-control" th:field="*{projection.hall.name}" required
autofocus="autofocus" />
</div>
<div class="form-group">
<label class="control-label" for="movieName"> Movie name </label> <input
id="movieName" class="form-control" th:field="*{projection.movie.movieName}" required
autofocus="autofocus" />
</div>
<div class="form-group">
<button type="submit" class="btn btn-success">Submit</button>
</div>
</form>
</div>
</div>
</div>
</body>
</html>

Use th:field="*{hall.name}" instead of th:field="*{projection.hall.name}" and th:field="*{movie.movieName}" instead of th:field="*{projection.movie.movieName}"

Pass two objects with bidirectional One to One relationship into one Thymeleaf form

I'm working on a JPA project in which I have two models: TableDecor and Product Tag, which look like this:
#Entity(name="table_decor")
public class TableDecor {
#Id
#IdConstraint
private String id;
#Positive
#Column(nullable = false)
private int width;
#Positive
#Column(nullable = false)
private int height;
#NotNull
#Enumerated(EnumType.STRING)
#Column(nullable = false)
private Color color;
#NotNull
#Enumerated(EnumType.STRING)
#Column(nullable = false)
private Fabric fabric;
#ManyToMany
#JoinTable(
name = "seller",
joinColumns = #JoinColumn(name = "table_decor_id"),
inverseJoinColumns = #JoinColumn(name = "seller_id"))
private List<Seller> sellers;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name="producer_id")
private Producer producer;
#OneToOne(cascade=CascadeType.ALL, fetch = FetchType.LAZY)
#JoinColumn(name = "product_tag_id", referencedColumnName = "id")
private ProductTag productTag;
// getters, setters
#Entity(name="product_tag")
#Table
public class ProductTag {
#Id
#GeneratedValue
private UUID id;
#NotNull
#Enumerated
#Column(nullable = false)
private ProductState productState;
#Column(nullable = false)
#NotNull
private float price;
#OneToOne(cascade=CascadeType.ALL, fetch = FetchType.EAGER)
#JoinColumn(name = "table_decor_id", referencedColumnName = "id")
private TableDecor tableDecor;
// getters, setters
As you can see they're connected with each other with bidirectional one to one relationship. Since one can't exist without another, how can I create a Thymeleaf add form that could create both objects at the same time? The controller function currently looks like this:
#GetMapping("/table-decor/add")
public String showAddForm(TableDecor decorToAdd, ProductTag productTag) {
return "table-decor-add";
}
#PostMapping("/table-decor/add-new")
public String addTableDecor(#Valid TableDecor decorToAdd, #Valid ProductTag productTag, BindingResult bindingResult, Model model){
if (bindingResult.hasErrors()) {
System.out.println("Error");
return "table-decor-add";
}
decorToAdd.setProductTag(productTag);
tableDecorService.addTableDecor(decorToAdd);
model.addAttribute("allTableDecor", tableDecorService.getAllTableDecor());
return "redirect:/table-decor";
and the form:
<form action="#" method="post" th:action="#{/table-decor/add-new}">
<div><input name="id" type="text" th:value="${tableDecor.id}"></div>
<span th:if="${#fields.hasErrors('tableDecor.id')}" th:errors="*{tableDecor.id}"></span>
<div><input name="width" type="text" th:value="${tableDecor.width}"></div>
<span th:if="${#fields.hasErrors('tableDecor.width')}" th:errors="*{tableDecor.width}"></span>
<div><input name="height" type="text" th:value="${tableDecor.height}"></div>
<span th:if="${#fields.hasErrors('tableDecor.height')}" th:errors="*{tableDecor.height}"></span>
<select name="color">
<option th:each="color : ${T(jee.labs.lab05.domain.Color).values()}"
th:text="${color}"
th:value="${tableDecor.color}">
</option>
</select>
<select name="fabric">
<option th:each="fabric : ${T(jee.labs.lab05.domain.Fabric).values()}"
th:text="${fabric}"
th:value="${tableDecor.fabric}">
</option>
</select>
<select name="productState">
<option th:each="productState : ${T(jee.labs.lab05.domain.ProductState).values()}"
th:text="${productState}"
th:value="${productTag.productState}">
</option>
</select>
<div><input name="price" type="text" th:value="${productTag.price}"></div>
<span th:if="${#fields.hasErrors('productTag.price')}" th:errors="*{productTag.price}"></span>
<div><input type="submit" th:value="Submit"></div>
</form>

Spring web mvc + Thymeleaf ModelAttribute editing the list in the object

I have a form for editing a user, the user has roles, which are a list of objects of type Authority, I want to be able to use checkboxes (optional) to set the roles that the user will have, but I have no idea how to implement the form in thymeleaf and how to pass the user object with the given roles to the controller.
It's my user
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.security.core.userdetails.UserDetails;
import javax.persistence.*;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.Size;
import java.util.HashSet;
import java.util.Set;
#Entity
#Table(name = "users")
#Data
#NoArgsConstructor
public class User implements UserDetails {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#Column(name="username", nullable = false, unique = true)
#NotBlank #Size(min=5, message = "Не менeе 5 знаков")
private String username;
#NotBlank #Size(min=5, message = "Не менeе 5 знаков")
#Column(name = "password")
private String password;
#Column(name = "enabled")
private boolean enabled;
#Column(name = "name")
private String name;
#Column(name = "surname")
private String surname;
#Column(name = "email", nullable = false, unique = true)
private String email;
#ManyToMany(cascade = {
CascadeType.PERSIST,
CascadeType.MERGE,
CascadeType.DETACH,
CascadeType.REFRESH
}, fetch = FetchType.EAGER)
#JoinTable(
name = "users_authorities",
joinColumns = #JoinColumn(name = "user_id"),
inverseJoinColumns = #JoinColumn(name = "authority_id")
)
private Set<Authority> authorities = new HashSet<>();
public User(String username, String password, boolean enabled,
String name, String surname, String email) {
this.username = username;
this.password = password;
this.enabled = enabled;
this.name = name;
this.surname = surname;
this.email = email;
}
public void addAuthority(Authority authority) {
this.authorities.add(authority);
}
#Override
public boolean isAccountNonExpired() {
return true;
}
#Override
public boolean isAccountNonLocked() {
return true;
}
#Override
public boolean isCredentialsNonExpired() {
return true;
}
}
It's my edit user form contoller
#GetMapping("/users/{id}/edit")
public String editUser(#PathVariable("id") Long id, Model model) {
model.addAttribute("user", userService.findById(id));
model.addAttribute("allAuthorities", authorityService.findAll());
return "users/edit-user";
}
It's my edit user form view
<body>
<form th:method="PUT" th:action="#{/admin/users/{id}(id=${user.getId()})}" th:object="${user}">
<input type="hidden" th:field="*{id}" id="id">
<label for="username">Username: </label>
<input type="text" th:field="*{username}" id="username" placeholder="username">
<br><br>
<div sec:authorize="hasRole('ROLE_ADMIN')">
<label for="enabled">Enabled </label>
<input type="checkbox" name="enabled" th:field="*{enabled}" id="enabled">
<br><br>
</div>
<label for="name">Name: </label>
<input type="text" th:field="*{name}" id="name" placeholder="Name">
<br><br>
<label for="surname">Surname: </label>
<input type="text" th:field="*{surname}" id="surname" placeholder="Surname">
<br><br>
<label for="email">Email: </label>
<input type="text" th:field="*{email}" id="email" placeholder="Email">
<br><br>
<div th:each="auth:${allAuthorities}">
<label>
<span th:text="${auth.authority}"></span>
<input type="checkbox" name="authorities" th:checked="${user.authorities.contains(auth)}">
</label>
</div>
<input type="submit" value="Edit">
</form>
</body>
It's put contoller, it getting the data from my form
#PutMapping("/users/{id}")
public String editUser(#PathVariable("id") Long id,
#ModelAttribute("user") User user,
#RequestParam("authorities") List<Authority> authorities) {
user.setId(id);
userService.update(user);
return "redirect:/admin/users";
}
And it's my Authority class if you need
#Entity
#Table(name = "authorities")
#Data
#NoArgsConstructor
public class Authority implements GrantedAuthority {
#Id
private Long id;
#Column(name = "authority")
private String authority;
#Transient
#ManyToMany(mappedBy = "authorities")
private Set<User> users;
public Authority(Long id, String authority) {
this.id = id;
this.authority = authority;
}
}
I'm try to pass the list of roles separately from the user object, but this also doesn't work and gives a bad request error.

To solve the problem, I added a new checked field to Entity authority
#Entity
#Table(name = "authorities")
#Data
#NoArgsConstructor
public class Authority implements GrantedAuthority {
#Id
private Long id;
#Column(name = "authority", nullable = false, unique = true)
private String authority;
#Transient
private boolean checked;
public Authority(Long id, String authority) {
this.id = id;
this.authority = authority;
}
}
Before sending the view to it, I changed the authorites field of the user object.
#GetMapping("/users/{id}/edit")
public String editUser(#PathVariable("id") Long id, Model model) {
User user = userService.findById(id);
List<Authority> allAuthorities = authorityService.findAll();
for(Authority auth : allAuthorities) {
if(user.getAuthorities().contains(auth)) {
auth.setChecked(true);
}
}
user.setAuthorities(allAuthorities);
model.addAttribute("user", user);
return "users/edit-user";
}
I also changed the thymeleaf template
<form th:method="PUT" th:action="#{/admin/users/{id}(id=${user.getId()})}" th:object="${user}">
<label for="username">Username: </label>
<input type="text" th:field="*{username}" id="username" placeholder="username">
<br><br>
<div sec:authorize="hasRole('ROLE_ADMIN')">
<label for="enabled">Enabled </label>
<input type="checkbox" name="enabled" th:field="*{enabled}" id="enabled">
<br><br>
</div>
<label for="name">Name: </label>
<input type="text" th:field="*{name}" id="name" placeholder="Name">
<br><br>
<label for="surname">Surname: </label>
<input type="text" th:field="*{surname}" id="surname" placeholder="Surname">
<br><br>
<label for="email">Email: </label>
<input type="text" th:field="*{email}" id="email" placeholder="Email">
<br><br>
<div th:each="auth, itemStat: ${user.authorities}">
<label>
<span th:text="${auth.authority}"></span>
<input type="hidden"
th:field="*{authorities[__${itemStat.index}__].id}">
<input type="hidden"
th:field="*{authorities[__${itemStat.index}__].authority}">
<input type="checkbox" th:checked="${auth.checked}"
th:field="*{authorities[__${itemStat.index}__].checked}">
</label>
</div>
<input type="submit" value="Edit">
</form>
My put controller looks like this
#PutMapping("/users/{id}")
public String editUser(#PathVariable("id") Long id,
#ModelAttribute("user") User user) {
List<Authority> userAuthorities = user.getAuthorities();
userAuthorities.removeIf(auth -> !auth.isChecked());
user.setId(id);
userService.update(user);
return "redirect:/admin/users";
}
My save and delete methods from UserService look like this(If that would be useful)
#Override
#Transactional
public User save(User user) {
Optional<User> userFromDB = userRepository.findByUsername(user.getUsername());
Optional<Authority> userRole;
if(userFromDB.isPresent()) {
return null;
}
userRole = authorityRepository.findByAuthority("ROLE_USER");
user.setPassword(bCryptPasswordEncoder.encode(user.getPassword()));
userRole.ifPresent(user::addAuthority);
return userRepository.save(user);
}
#Override
#Transactional
public User update(User user) {
Optional<User> userFromDB = userRepository.findById(user.getId());
if(userFromDB.isPresent()){
//Adding the password for successfully update user in DB
user.setPassword(userFromDB.get().getPassword());
return userRepository.save(user);
}
return null;
}
This may not be the most elegant solution but I haven't found another one yet

Exception evaluating SpringEL expression: "#fields.hasErrors('something')"

I try to make a register page for my application and when I press submit button this error appears:
Exception evaluating SpringEL expression: "#fields.hasErrors('firstName')"
From what I understand, Thymleaf uses POJO's getters for validation and this means that firstName attribute couldn't be found. For registration I use a DTO for user entity, a DTO only for registration. If i use user entity this error never appears. What am I doing wrong?
<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml"
xmlns:th="http://www.thymeleaf.org">
<head>
<title>Registration Form</title>
<link rel="stylesheet" type="text/css" th:href="#{/css/registration.css}"/>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
<div class="row">
<div class="col-md-6 col-md-offset-3">
<form autocomplete="on" action="register.html" th:action="#{/user/register}"
th:object="${user}" method="post" class="form-horizontal"
role="form">
<h2>Registration Form</h2>
<div class="form-group">
<div class="col-sm-9">
<label th:if="${#fields.hasErrors('firstName')}" th:errors="*{firstName}"
class="validation-message"></label>
<input type="text" th:field="*{firstName}" placeholder="Name"
class="form-control"/>
</div>
</div>
<div class="form-group">
<div class="col-sm-9">
<label th:if="${#fields.hasErrors('lastName')}" th:errors="*{lastName}"
class="validation-message"></label>
<input type="text" th:field="*{lastName}"
placeholder="Last Name" class="form-control"/>
</div>
</div>
<div class="form-group">
<div class="col-sm-9">
<label th:if="${#fields.hasErrors('username')}" th:errors="*{username}"
class="validation-message"></label>
<input type="text" th:field="*{username}"
placeholder="Username" class="form-control"/>
</div>
</div>
<div class="form-group">
<div class="col-sm-9">
<input type="text" th:field="*{emailAddress}" placeholder="Email"
class="form-control"/> <label
th:if="${#fields.hasErrors('emailAddress')}" th:errors="*{emailAddress}"
class="validation-message"></label>
</div>
</div>
<div class="form-group">
<div class="col-sm-9">
<label th:if="${#fields.hasErrors('phoneNumber')}" th:errors="*{phoneNumber}"
class="validation-message"></label>
<input type="text" th:field="*{phoneNumber}"
placeholder="Phone Number" class="form-control"/>
</div>
</div>
<div class="form-group">
<div class="col-sm-9">
<input type="password" th:field="*{password}"
placeholder="Password" class="form-control"/> <label
th:if="${#fields.hasErrors('password')}" th:errors="*{password}"
class="validation-message"></label>
</div>
</div>
<div class="form-group">
<div class="col-sm-9">
<input type="password" th:field="*{confirmPassword}"
placeholder="Confirm Password" class="form-control"/> <label
th:if="${#fields.hasErrors('confirmPassword')}" th:errors="*{confirmPassword}"
class="validation-message"></label>
</div>
</div>
<div class="form-group">
<div class="col-sm-9">
<button type="submit" class="btn btn-primary btn-block">Register User</button>
</div>
</div>
<h2><span class="text-success" th:utext="${successMessage}"></span></h2>
</form>
</div>
</div>
</div>
</body>
</html>
RegisterUserDto
#PasswordMatches
public class RegisterUserDto {
private Long id;
#NotNull(message = "This field can't be null")
#NotEmpty(message = "This field can't be empty")
private String firstName;
#NotNull(message = "This field can't be null")
#NotEmpty(message = "This field can't be empty")
private String lastName;
#NotNull(message = "This field can't be null")
#NotEmpty(message = "This field can't be empty")
private String username;
#NotNull(message = "This field can't be null")
#NotEmpty(message = "This field can't be empty")
#ValidEmail
private String emailAddress;
#NotNull(message = "This field can't be null")
#NotEmpty(message = "This field can't be empty")
#ValidPhoneNumber
private String phoneNumber;
#ValidPassword
private String password;
private String confirmPassword;
//getters and setters
Controller
#GetMapping("/register")
public ModelAndView registration(){
ModelAndView modelAndView = new ModelAndView();
RegisterUserDto user = new RegisterUserDto();
modelAndView.addObject("user", user);
modelAndView.setViewName("register");
return modelAndView;
}
#PostMapping("/register")
public ModelAndView createNewUser(#Valid RegisterUserDto user,
BindingResult bindingResult) {
ModelAndView modelAndView = new ModelAndView();
User userExists = userService.findUserByEmail(user.getEmailAddress());
if (userExists != null) {
bindingResult
.rejectValue("emailAddress", "error.user",
"There is already a user registered with the email provided");
}
if (bindingResult.hasErrors()) {
modelAndView.setViewName("register");
} else {
userService.createUser(user);
modelAndView.addObject("successMessage", "User has been registered successfully");
modelAndView.setViewName("register");
}
return modelAndView;
}
User entity
#Entity
#Table(name = "user")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "user_id")
private Long id;
#Column(name = "first_name")
private String firstName;
#Column(name = "last_name")
private String lastName;
#Column(name = "username",
unique = true)
private String username;
#Column(name = "email_address",
unique = true)
private String emailAddress;
#Column(name = "phone_number")
private String phoneNumber;
#Column(name = "password")
private String password;
#Column(name = "notification_type",
insertable = false)
private String notificationType = "email";
#Column(name = "date_created")
private Date dateCreated;
#Column(name = "is_active",
insertable = false)
private Boolean active = false;
#OneToMany(
mappedBy = "user",
cascade = CascadeType.ALL,
orphanRemoval = true
)
private List<UserGroup> groups;
#OneToMany(
mappedBy = "user",
cascade = CascadeType.ALL,
orphanRemoval = true
)
private List<Message> messages = new ArrayList<>();
#OneToOne(fetch = FetchType.LAZY,
cascade = {CascadeType.DETACH, CascadeType.MERGE,
CascadeType.REFRESH, CascadeType.PERSIST},
mappedBy = "userId",
orphanRemoval = true)
private VerificationToken verificationToken;
#OneToMany(mappedBy = "createdBy",
cascade = {CascadeType.DETACH, CascadeType.MERGE,
CascadeType.REFRESH, CascadeType.PERSIST},
orphanRemoval = true)
private List<Group> createdGroups = new ArrayList<>();
//getters and setters

Unable to save entity using thymeleaf and Spring Boot

I've recently started using Spring Boot (I mostly come from a python/flask and node background) with JPA and thymeleaf and I'm trying to create a Project in my database. Everything was going well, I was able to add, delete, etc.. Projects.
I added a variable Set users to my Project entity which looks like this:
#Entity
#Table(name = "project")
public class Project {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(name = "project_id")
private int id;
#Column(name = "title")
#NotEmpty(message = "*Please provide a title")
private String title;
#Column(name = "description")
private String description;
#OneToOne(cascade = CascadeType.ALL)
#JoinTable(name = "project_lead", joinColumns = #JoinColumn(name = "project_id"), inverseJoinColumns = #JoinColumn(name = "user_id"))
private User projectLead;
#ManyToMany(cascade = CascadeType.ALL)
#JoinTable(name = "project_user", joinColumns = #JoinColumn(name = "project_id"), inverseJoinColumns = #JoinColumn(name = "user_id"))
private Set<User> users;
...
}
The user class looks like this:
#Entity
#Table(name = "user")
public class User {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(name = "user_id")
private int id;
#Column(name = "email")
#Email(message = "*Please provide a valid Email")
#NotEmpty(message = "*Please provide an email")
private String email;
#Column(name = "username")
#NotEmpty(message = "*Please provide a username")
private String username;
#Column(name = "password")
#Length(min = 5, message = "*Your password must have at least 5 characters")
#NotEmpty(message = "*Please provide your password")
#Transient
private String password;
#Column(name = "enabled")
private int enabled;
#ManyToMany(cascade = CascadeType.ALL)
#JoinTable(name = "user_role", joinColumns = #JoinColumn(name = "user_id"), inverseJoinColumns = #JoinColumn(name = "role_id"))
private Set<Role> roles;
...
}
I'm able to create new projects when I don't specify the users for the project. But I'm having trouble creating a project when I specify the users using a multiple select. In my form I have:
<form th:action="#{/secure/projects}" th:object="${project}" method="POST">
<div class="form-group">
<label th:if="${#fields.hasErrors('title')}" th:errors="*{title}" class="validation-message"></label>
<input type="text" class="form-control" th:field="*{title}" id="title" th:placeholder="Title" />
</div>
<div class="form-group">
<input type="text" class="form-control" th:field="*{description}" id="description" th:placeholder="Description" />
</div>
<div class="form-group">
<select th:field="*{users}" class="users-select form-control" multiple="multiple">
<option th:each="user : ${allUsers}" th:value="${user}" th:text="${user.username}"></option>
</select>
</div>
<button name="Submit" value="Submit" type="Submit" th:text="Create"></button>
</form>
I keep getting 'Failed to convert property value of type 'java.lang.String' to required type 'java.util.Set' for property 'users'' for the th:field="*{users}". I don't understand why th:value="${user}" is being considered as a String when it's supposed to be of class User. Is there a way for me to simply get the results of the select, loop through it and manually add it in the controller to my object project?
My controller looks like this:
#RequestMapping(value = "/projects", method=RequestMethod.GET)
public ModelAndView showProjectForm() {
ModelAndView modelAndView = new ModelAndView();
// Get authenticated user
Authentication auth = SecurityContextHolder.getContext().getAuthentication();
User user = userService.findByEmail(auth.getName());
modelAndView.addObject("userName", "Welcome " + user.getUsername() + " (" + user.getEmail() + ")");
modelAndView.addObject("project", new Project());
modelAndView.addObject("allUsers", userService.findAll());
modelAndView.setViewName("project_creation");
return modelAndView;
}
#RequestMapping(value = "/projects", method=RequestMethod.POST)
public ModelAndView processProjectForm(#Valid Project project, BindingResult bindingResult) {
ModelAndView modelAndView = new ModelAndView();
// Get authenticated user
Authentication auth = SecurityContextHolder.getContext().getAuthentication();
User user = userService.findByEmail(auth.getName());
// Get all projects
List<Project> allProjects = projectService.findAll();
// Check if project already exists
Project projectExist = projectService.findByTitle(project.getTitle());
if(projectExist != null) {
bindingResult
.rejectValue("title", "error.project",
"There is already a project with this title");
}
// Get all users
List<User> allUsers = userService.findAll();
if(bindingResult.hasErrors()) {
modelAndView.addObject("userName", "Welcome " + user.getUsername() + " (" + user.getEmail() + ")");
modelAndView.addObject("project", new Project());
modelAndView.addObject("allUsers", allUsers);
modelAndView.setViewName("project_creation");
} else {
// Create project
project.setProjectLead(user);
projectService.saveProject(project);
modelAndView.addObject("userName", "Welcome " + user.getUsername() + " (" + user.getEmail() + ")");
modelAndView.addObject("success", "Project successfully created!");
modelAndView.addObject("project", new Project());
modelAndView.addObject("projects", allProjects);
modelAndView.setViewName("redirect:/secure/dashboard");
}
return modelAndView;
}

I was able to fix the 'Failed to convert property value of type 'java.lang.String' to required type 'java.util.Set' for property 'users''. I simply had to add a converter class telling how to convert from string to User object.
#Component
public class StringToUser implements Converter<String, User> {
#Autowired
private UserService userService;
#Override
public User convert(String arg0) {
Integer id = new Integer(arg0);
return userService.findOne(id);
}
}
And changed the option in my form to have a value of user.id instead of a user object. The converter would take care of the rest:
<option th:each="user : ${allUsers}" th:value="${user.getId()}" th:text="${user.getUsername()}"></option>