EL1007E: Property or field 'classes' cannot be found on null - while trying to display name of classes in html

Question

I am trying to get data from multiple tables in Spring Data JPA.

User.java

@Entity
@Table(name = "user")
public class User{

    @Id
    @GeneratedValue(strategy = GenerationType.TABLE)
    private Long id;


    private String username;

    private String password;

   //Getters and setters generated

    @ManyToMany(fetch = FetchType.LAZY, cascade = { CascadeType.MERGE, CascadeType.PERSIST })
    private List<Classes> classes;

Classes.java

@Entity
public class Classes {

    @Id
    @GeneratedValue(strategy = GenerationType.TABLE)
    private Long id;

    private String name;

    @Lob
    private String description;

    @ManyToMany(mappedBy = "classes", fetch = FetchType.EAGER, cascade = { CascadeType.MERGE, CascadeType.PERSIST })
    private List<User> user;

These entities generate table named as 'user_classes' and fields as following classes_id and user_id

I am trying to display name of classes that belong to that particular user. As I have my models designed as shown above I am trying to do it like this

<tr th:each="classes : ${user.classes}">
    <td th:text="${classes.name}"></td>
</tr>

My table in database looks like this

Database table

So class and user do exist.

But I am facing this error

EL1007E: Property or field 'classes' cannot be found on null

I am not sure what I am doing wrong?

Answer 1

Mistake was in spelling. I have passed User object Thymeleaf view as

<tbody th:each="users : ${users}">

And I was trying to reach it as

<tr th:each="classes : ${user.classes}">
    <td th:text="${classes.name}"></td>
</tr> 

Where part ${user.classes} didn't work. When I wrote user object as users or like this ${users.classes} everything worked!