Spring + JPA( Hibernate) ORM
I try to make a mini forum and I'm stuck. How it should be, first of all, you create a post and write a message of a topic, it redirects to all post and adds new posted which you created, a user clicks on a post and it shows in next page all message which filled in. Also I made a comment system, I every post has to have comments, so the problem is in my code which is below, when I tried to make that comments work, it works like this: doesn't matter what post id you choose it shows all comments which do exist, so I changed and failed. May someone explains me, how to make correct with Hibernate.
PostController is: pay attention to method seeMessage, it finds the post by id and shows message.
package com.pandora.controllers;
import com.pandora.domain.Post;
import com.pandora.services.CommentService;
import com.pandora.services.PostService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
@Controller
@RequestMapping("/posts")
public class PostController {
@Autowired
private PostService postService;
@Autowired
private CommentService commentService;
@RequestMapping
public String findAll(Model model) {
model.addAttribute("posts", postService.findAll());
return "post/post";
}
@RequestMapping(value = "/click", method = RequestMethod.GET)
public String click() {
return "post/new";
}
@RequestMapping(value = "/add", method = RequestMethod.POST)
public String addPost(@ModelAttribute Post post) {
postService.addPost(post);
return "redirect:/posts";
}
@RequestMapping(value = "/{title}/find", method = RequestMethod.GET)
public String findByName(@PathVariable String title) {
postService.findByTitle(title);
return "redirect:/posts";
}
@RequestMapping(value = "/{id}/see", method = RequestMethod.GET)
public String seeMessage(@PathVariable long id, Model model) {
Post post = postService.findById(id);
System.out.println("the id is " + id);
System.out.println("the value of comments are " +post.getComments().size());
model.addAttribute("post", post);
// model.addAttribute("postMessage", post.getComments());
return "post/postmessage";
}
@RequestMapping(value = "/{id}/delete")
public String delete(@PathVariable long id) {
postService.delete(id);
return "redirect:/posts";
}
@RequestMapping(value = "/login", method = RequestMethod.GET)
public String login(){
return "login";
}
}
CommentController is: And here pay attention on method addComment, first I find from what id post it went and after this I have to add comment to founded post.
package com.pandora.controllers;
import com.pandora.domain.Comment;
import com.pandora.domain.Post;
import com.pandora.services.CommentService;
import com.pandora.services.PostService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import java.util.ArrayList;
import java.util.List;
@Controller
@RequestMapping("/comments")
public class CommentController {
@Autowired
private CommentService commentService;
@Autowired
private PostService postService;
@RequestMapping(value = "/post/{postId}/comment", method = RequestMethod.POST)
public String addComment(@PathVariable long postId, @ModelAttribute Comment comment){
Post post = postService.findById(postId);
System.out.println(post.getId());
System.out.println(comment.getMessage());
List comments = new ArrayList();
comments.add(commentService.addComment(comment));
post.setComments(comments);
return "redirect:/posts";
}
@RequestMapping(value = "/{id}/delete", method = RequestMethod.GET)
public String delete(@PathVariable long id){
commentService.delete(id);
return "redirect:/posts";
}
}
Post entity is:
package com.pandora.domain;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import javax.persistence.*;
import java.util.List;
@Entity
@Setter
@Getter
@NoArgsConstructor
public class Post {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "post")
private List comments;
@Column(length = 10000)
private String message;
private String title;
}
PostService is:
package com.pandora.services;
import com.pandora.domain.Post;
import com.pandora.domain.repositories.PostRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class PostService {
@Autowired
private PostRepository postRepository;
public Post addPost(Post post){
return postRepository.saveAndFlush(post);
}
public List findAll(){
return postRepository.findAll();
}
public Post findByTitle(String title){
return postRepository.findByTitle(title);
}
public Post findById(long id){
return postRepository.findOne(id);
}
public void delete(long id){
postRepository.delete(id);
}
}
Comment entity is:
package com.pandora.domain;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import javax.persistence.*;
@Entity
@Setter
@Getter
@NoArgsConstructor
public class Comment {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@ManyToOne(fetch = FetchType.EAGER)
private Post post;
private String message;
}
and CommentService is :
package com.pandora.services;
import com.pandora.domain.Comment;
import com.pandora.domain.repositories.CommentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class CommentService {
@Autowired
private CommentRepository commentRepository;
public Comment addComment(Comment comment){
return commentRepository.saveAndFlush(comment);
}
public List findAll(){
return commentRepository.findAll();
}
public void delete(long id){
commentRepository.delete(id);
}
public Comment findOne(long id){
return commentRepository.findOne(id);
}
}
and HTML which shows post which chooses by it is: here pay attention to the: each div container. I retrieve from a list which is gone from PostController comments. But it doesn't work because when I do it it's always empty. I don't know why it's empty.
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org"
layout:decorator="layout">
<div layout:fragment="content">
<h2 align="center">
<h2 align="left">
<div th:text="${post.title}"></div>
</h2>
</h2>
<h4 align="center">
<div th:text="${post.message}"></div>
</h4>
<hr/>
<h4>Comments:</h4>
<br/>
<h4>
<div th:each="comments : ${post}">
<label for="username"><div th:inline="text">[[${#httpServletRequest.remoteUser}]]: </div> </label>
<div th:each="comment : ${comments.comments}">
<div id="username" th:text="${comment}"></div>
</div>
</div>
</h4>
<br/>
<form method="post" name="comment_form" id="comment_form" th:action="@{'/comments/post/{id}/comment'(id=${post.id}) }" role="form">
<div class="form-group">
<label for="message">Comment</label>
<textarea rows="5" class="form-control" id="message" name="message"/>
</div>
<button type="submit" id="submit" class="btn btn-primary">Submit</button>
</form>
</div>
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