Add Tags Support to Blog Posts

README.md

@@ -10,7 +10,7 @@ A simple blog system using microservices architecture with go-micro v5.
 The project consists of the following microservices:
 
 1. **Users Service**: User management (create, read, update, delete)
-2. **Posts Service**: Post management (create, read, delete, list)
+2. **Posts Service**: Post management (create, read, delete, list, tag management)
 3. **Comments Service**: Comment management (create, read, delete, list)
 4. **Web Service**: REST API that uses all other services
 
@@ -29,6 +29,14 @@ Just start the web service as shown below, then open http://localhost:42096 in y
 
 Authentication and profile features are available via the UI. The static UI interacts with the REST API provided by the web service.
 
+### Tag Features
+
+The blog allows you to:
+- Add tags to posts
+- Remove tags from posts
+- Filter the feed to show posts with a specific tag
+- Browse all available tags
+
 ## Getting Started
 
 ### Prerequisites
@@ -129,6 +137,19 @@ The REST API and web interface will be available at http://localhost:42096
 - `POST /logout`: Log out the current user
 - `GET /users/me`: Get the current session user info
 
+### Tags
+
+- `POST /posts/:id/tags`: Add a tag to a post
+  ```json
+  {
+    "tag": "tagname"
+  }
+  ```
+- `DELETE /posts/:id/tags/:tag`: Remove a tag from a post
+- `GET /tags`: Get all available tags
+- `GET /tags?post_id=:id`: Get tags for a specific post
+- `GET /posts/by-tag/:tag`: Get posts with a specific tag
+
 ## Project Structure
 
 ```

posts/handler/posts.go

@@ -118,3 +118,136 @@ func (h *Handler) List(ctx context.Context, req *pb.ListRequest, res *pb.ListRes
 	res.Total = 0
 	return nil
 }
+
+func (h *Handler) TagPost(ctx context.Context, req *pb.TagPostRequest, res *pb.TagPostResponse) error {
+	if req.PostId == "" || req.Tag == "" {
+		return nil
+	}
+
+	rec, err := postStore.Read("post-" + req.PostId)
+	if err != nil || len(rec) == 0 {
+		return nil
+	}
+
+	var post pb.Post
+	if err := json.Unmarshal(rec[0].Value, &post); err != nil {
+		return nil
+	}
+
+	// Initialize tags slice if it doesn't exist
+	if post.Tags == nil {
+		post.Tags = []string{}
+	}
+
+	// Check if tag already exists for this post
+	for _, tag := range post.Tags {
+		if tag == req.Tag {
+			// Tag already exists, return the post as is
+			res.Post = &post
+			return nil
+		}
+	}
+
+	// Add the new tag
+	post.Tags = append(post.Tags, req.Tag)
+	post.UpdatedAt = time.Now().Unix()
+
+	// Save the updated post
+	b, err := json.Marshal(&post)
+	if err == nil {
+		_ = postStore.Write(&store.Record{Key: "post-" + post.Id, Value: b})
+	}
+
+	res.Post = &post
+	return nil
+}
+
+func (h *Handler) UntagPost(ctx context.Context, req *pb.UntagPostRequest, res *pb.UntagPostResponse) error {
+	if req.PostId == "" || req.Tag == "" {
+		return nil
+	}
+
+	rec, err := postStore.Read("post-" + req.PostId)
+	if err != nil || len(rec) == 0 {
+		return nil
+	}
+
+	var post pb.Post
+	if err := json.Unmarshal(rec[0].Value, &post); err != nil {
+		return nil
+	}
+
+	if len(post.Tags) == 0 {
+		res.Post = &post
+		return nil
+	}
+
+	updatedTags := []string{}
+	for _, tag := range post.Tags {
+		if tag != req.Tag {
+			updatedTags = append(updatedTags, tag)
+		}
+	}
+
+	// Update the post only if tags were changed
+	if len(updatedTags) != len(post.Tags) {
+		post.Tags = updatedTags
+		post.UpdatedAt = time.Now().Unix()
+
+		// Save the updated post
+		b, err := json.Marshal(&post)
+		if err == nil {
+			_ = postStore.Write(&store.Record{Key: "post-" + post.Id, Value: b})
+		}
+	}
+
+	res.Post = &post
+	return nil
+}
+
+func (h *Handler) ListTags(ctx context.Context, req *pb.ListTagsRequest, res *pb.ListTagsResponse) error {
+	// If postId is specified, get tags for that specific post
+	if req.PostId != "" {
+		rec, err := postStore.Read("post-" + req.PostId)
+		if err != nil || len(rec) == 0 {
+			return nil
+		}
+
+		var post pb.Post
+		if err := json.Unmarshal(rec[0].Value, &post); err != nil {
+			return nil
+		}
+
+		res.Tags = post.Tags
+		return nil
+	}
+
+	// Otherwise, collect all unique tags across all posts
+	allTags := make(map[string]struct{})
+
+	rec, err := postStore.Read("post-", store.ReadPrefix())
+	if err != nil || len(rec) == 0 {
+		return nil
+	}
+
+	for _, r := range rec {
+		var post pb.Post
+		if err := json.Unmarshal(r.Value, &post); err == nil {
+			for _, tag := range post.Tags {
+				allTags[tag] = struct{}{}
+			}
+		}
+	}
+
+	// Convert map keys to slice
+	uniqueTags := make([]string, 0, len(allTags))
+	for tag := range allTags {
+		uniqueTags = append(uniqueTags, tag)
+	}
+
+	// Sort tags alphabetically for consistent output
+	sort.Strings(uniqueTags)
+
+	res.Tags = uniqueTags
+	return nil
+}