@Entity
public class Users {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;

    @Column(nullable=false, length=30)
    private String username;

    @Column(nullable=false)
    private String hashPass;

    // Unique email
    @Column(nullable=false, unique=true)
    private String email;

    @Column(nullable=false)
    private String role;

    @OneToMany(mappedBy="author", cascade=CascadeType.ALL)
    private Set<Post> posts= new HashSet<>();

    public Users(){

    }

    public Users(String username){
        this.username=username;
    }

    public Users(String username, String hashPass, String email, String role) {
        super();
        this.username = username;
        this.hashPass = hashPass;
        this.email = email;
        this.role = role;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getHashPass() {
        return hashPass;
    }

    public void setHashPass(String hashPass) {
        this.hashPass = hashPass;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Set<Post> getPosts() {
        return posts;
    }

    public void setPosts(Set<Post> posts) {
        this.posts = posts;
    }


    public String getRole() {
        return role;
    }

    public void setRole(String role) {
        this.role = role;
    }

    @Override
    public String toString() {
        return "Users [id=" + id + ", username=" + username + ", hashPass=" + hashPass + ", email=" + email + ", role="
                + role + ", posts=" + posts + "]";
    }
}

@Entity
public class Post {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;

    @Column(nullable=false, length=300)
    private String title;

    @Column(nullable=false)
    private String body;

    @ManyToOne(optional=false, fetch=FetchType.LAZY)
    @JoinColumn
    private Users author;

    @Column(nullable=false)
    private Date date= new Date();

    public Post(){

    }

    public Post(String title, String body, Users author){
        super();
        this.title=title;
        this.body=body;
        this.author=author;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getBody() {
        return body;
    }

    public void setBody(String body) {
        this.body = body;
    }

    public Users getAuthor() {
        return author;
    }

    public void setAuthor(Users author) {
        this.author = author;
    }

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

    @Override
    public String toString() {
        return "Post [id=" + id + ", title=" + title + ", body=" + body + ", author=" + author + ", date=" + date + "]";
    }


}

//  POST CONTROLLER
    //Add Posts
@RequestMapping(value="/posts/create", method=RequestMethod.GET)
public String addPost(String username, Model model){
    model.addAttribute("add", new Post());
    model.addAttribute("author", uRepo.findByUsername(username));
    return "posts/create";

}
//Save post
    @RequestMapping(value="/posts/savePost", method=RequestMethod.POST)
    public String savePost(Post post){
        pRepo.save(post);
        return "redirect:/";
}

<div class="container">
    <h1>Add Post</h1>
        <form th:object="${add}" th:action="@{savePost}" action="#" method="post" class="form-horizontal">
            <div class="form-group">
            <label class="control-label col-sm-2" for="title">Title</label>
            <div class="col-sm-10"><input type="text" id="title" th:field="*{title}" /></div>
            </div>

            <div class="form-group">
            <label class="control-label col-sm-2" for="body">Body:</label>
            <div class="col-sm-10">
                <textarea rows="10" id="body" th:field="*{body}"></textarea>
            </div>
            </div>

            <div class="form-group">
            <label class="control-label col-sm-2" for="author">Author:</label>
            <div class="col-sm-10">
                <p th:inline="text" id="author"  th:field="*{author}">[[${#httpServletRequest.remoteUser}]] <span th:sec:authentication="name"></span></p>
            </div>
            </div>
            <br/>
            <input type="submit" value="Save" class="btn btn-info"></input>
        </form>
</div>