finish postTagService and test, modify sth in postService

Change-Id: I76b5982f578b5bffe3c48b0afeda219e01307455
diff --git a/src/main/java/com/example/g8backend/service/IPostService.java b/src/main/java/com/example/g8backend/service/IPostService.java
index f81053e..f914946 100644
--- a/src/main/java/com/example/g8backend/service/IPostService.java
+++ b/src/main/java/com/example/g8backend/service/IPostService.java
@@ -2,11 +2,13 @@
 
 import com.example.g8backend.entity.Post;
 import com.baomidou.mybatisplus.extension.service.IService;
+
 import java.util.List;
 
 public interface IPostService extends IService<Post> {
     List<Post> getPostsByUserId(Long userId);
-    Post createPost(Post post);
+    void createPost(Post post);
+    void createPost(Post post, Long[] tagIds);
     Post updatePost(Post post);
     List<Post> getPostsByType(String postType);
     Long getPostLikeCount(Long postId);