working on ManyToMany

src/main/java/com/example/demo/models/BlogPost.java

@@ -4,6 +4,7 @@
 import com.fasterxml.jackson.annotation.JsonIgnore;
 
 import javax.persistence.*;
+import java.util.List;
 
 @Entity
 public class BlogPost {
@@ -18,16 +19,19 @@ public class BlogPost {
     @ManyToOne(cascade = CascadeType.ALL)
     @JsonIgnore
     private User user;
+    @ManyToMany(cascade = CascadeType.ALL)
+    private List<Tag> tags;
 
     public BlogPost() {
     }
 
-    public BlogPost(Long id, String title, String imageUrl, Recipe recipe, User user) {
+    public BlogPost(Long id, String title, String imageUrl, Recipe recipe, User user, List<Tag> tags) {
         this.id = id;
         this.title = title;
         this.imageUrl = imageUrl;
         this.recipe = recipe;
         this.user = user;
+        this.tags = tags;
     }
 
     public Long getId() {
@@ -61,4 +65,12 @@ public void setImageUrl(String imageUrl) {
     public User getUser() { return user; }
 
     public void setUser(User user) { this.user = user; }
+
+    public List<Tag> getTags() {
+        return tags;
+    }
+
+    public void setTags(List<Tag> tags) {
+        this.tags = tags;
+    }
 }

src/main/java/com/example/demo/models/Recipe.java

@@ -3,6 +3,7 @@
 import com.fasterxml.jackson.annotation.JsonIgnore;
 
 import javax.persistence.*;
+import java.util.List;
 
 @Entity
 public class Recipe {
@@ -63,4 +64,5 @@ public void setInstructions(String instructions) {
     public BlogPost getBlogPost() { return blogPost; }
 
     public void setBlogPost(BlogPost blogPost) { this.blogPost = blogPost; }
+
 }

src/main/java/com/example/demo/models/Tag.java

@@ -1,23 +1,24 @@
 package com.example.demo.models;
 
-import javax.persistence.Entity;
-import javax.persistence.GeneratedValue;
-import javax.persistence.GenerationType;
-import javax.persistence.Id;
+import javax.persistence.*;
+import java.util.List;
 
 @Entity
 public class Tag {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     Long id;
     String name;
+    @ManyToMany(cascade = CascadeType.ALL)
+    List<BlogPost> blogPosts;
 
     public Tag() {
     }
 
-    public Tag(Long id, String name) {
+    public Tag(Long id, String name, List<BlogPost> blogPosts) {
         this.id = id;
         this.name = name;
+        this.blogPosts = blogPosts;
     }
 
     public Long getId() {
@@ -35,6 +36,10 @@ public String getName() {
     public void setName(String name) {
         this.name = name;
     }
+
+    public List<BlogPost> getBlogPosts() { return blogPosts; }
+
+    public void setBlogPosts(List<BlogPost> blogPosts) { this.blogPosts = blogPosts; }
 }
 
 

src/main/java/com/example/demo/repository/BlogPostRepository.java

@@ -1,6 +1,7 @@
 package com.example.demo.repository;
 
 import com.example.demo.models.BlogPost;
+import com.example.demo.models.Tag;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.query.Param;
@@ -13,4 +14,7 @@ public interface BlogPostRepository extends CrudRepository<BlogPost, Long> {
 
     @Query(value = "SELECT * FROM blog_post b WHERE b.user_id = :userId", nativeQuery = true)
     List<BlogPost> findByUser(@Param("userId") Long userId);
+
+    @Query(value = "SELECT * FROM blog_post WHERE tag_id = :tagId", nativeQuery = true)
+    List<BlogPost> findByTag(@Param("tagId") Long tagId);
 }

src/main/java/com/example/demo/repository/TagRepository.java

@@ -1,9 +1,18 @@
 package com.example.demo.repository;
 
+import com.example.demo.models.BlogPost;
+import com.example.demo.models.Recipe;
 import com.example.demo.models.Tag;
+import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.repository.query.Param;
 import org.springframework.stereotype.Repository;
 
+import java.util.List;
+
 @Repository
 public interface TagRepository extends CrudRepository<Tag, Long> {
+
+    @Query(value = "SELECT * FROM tag WHERE tag.blog_post_id = :postId", nativeQuery = true)
+    List<Tag> findByBlogPost(@Param("postId") Long blogPostId);
 }

src/main/java/com/example/demo/service/BlogPostService.java

@@ -1,7 +1,9 @@
 package com.example.demo.service;
 
 import com.example.demo.models.BlogPost;
+import com.example.demo.models.User;
 import com.example.demo.repository.BlogPostRepository;
+import com.example.demo.repository.TagRepository;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 
@@ -12,15 +14,24 @@
 public class BlogPostService {
     @Autowired
     BlogPostRepository repository;
+    @Autowired
+    TagRepository tagRepository;
 
     public BlogPost create(BlogPost blogPost){return repository.save(blogPost);}
 
-    public BlogPost read(Long id){ return repository.findById(id).get();}
+    public BlogPost read(Long id){
+        BlogPost blogPost = repository.findById(id).get();
+        blogPost.setTags(tagRepository.findByBlogPost(id));
+        return blogPost;
+    }
 
     public List<BlogPost> readAll(){
         Iterable<BlogPost> blogPostsIterable = repository.findAll();
         List<BlogPost> result = new ArrayList<>();
         blogPostsIterable.forEach(result::add);
+        for(BlogPost blogPost : result) {
+            blogPost.setTags(tagRepository.findByBlogPost(blogPost.getId()));
+        }
         return result;
     }
 

src/main/java/com/example/demo/service/TagService.java

@@ -1,6 +1,8 @@
 package com.example.demo.service;
 
+import com.example.demo.models.BlogPost;
 import com.example.demo.models.Tag;
+import com.example.demo.repository.BlogPostRepository;
 import com.example.demo.repository.TagRepository;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
@@ -12,15 +14,24 @@
 public class TagService {
     @Autowired
     private TagRepository repository;
+    @Autowired
+    private BlogPostRepository blogPostRepository;
 
     public Tag create(Tag tag){ return repository.save(tag); }
 
-    public Tag read(Long id){ return repository.findById(id).get(); }
+    public Tag read(Long id){
+        Tag tag = repository.findById(id).get();
+        tag.setBlogPosts(blogPostRepository.findByTag(id));
+        return tag;
+    }
 
     public List<Tag> readAll(){
         Iterable<Tag> tagIterable = repository.findAll();
         List<Tag> result = new ArrayList<>();
         tagIterable.forEach(result::add);
+        for(Tag tag : result) {
+            tag.setBlogPosts(blogPostRepository.findByTag(tag.getId()));
+        }
         return result;
     }