example2: sample code for paginated posts

Author: pilinux

example2/README.md

@@ -240,10 +240,40 @@ Delete authenticated user account and all related posts/hobbies. _(Requires JWT)
 
 #### GET /posts
 
-Get all posts.
+Get all posts with pagination support.
+
+Query parameters:
+
+- `page` (optional): Page number, default: 1
+- `pageSize` (optional): Number of posts per page, default: 10, max: 100
 
 ```bash
+# Get first page with default page size (10)
 curl http://localhost:8999/api/v1/posts
+
+# Get page 2 with 1 post per page
+curl "http://localhost:8999/api/v1/posts?page=2&pageSize=1"
+```
+
+Response:
+
+```json
+{
+  "hasNext": true,
+  "hasPrevious": true,
+  "page": 2,
+  "pageSize": 1,
+  "posts": [
+    {
+      "postID": 8,
+      "createdAt": 1771575386,
+      "updatedAt": 1771575386,
+      "title": "My First Post",
+      "body": "Hello, gorest!"
+    }
+  ],
+  "total": 9
+}
 ```
 
 #### GET /posts/:id

example2/internal/handler/post.go

@@ -27,16 +27,45 @@ func NewPostAPI(postService *service.PostService) *PostAPI {
 	}
 }
 
-// GetPosts handles the HTTP GET request to retrieve all posts.
+// GetPosts handles the HTTP GET request to retrieve paginated posts.
 //
-// Endpoint: GET /api/v1/posts
+// Endpoint: GET /api/v1/posts?page=1&pageSize=10
+//
+// Optional query parameters:
+//   - page: page number (default: 1)
+//   - pageSize: number of posts per page (default: 10, max: 100)
 //
 // Authorization: None
 func (api *PostAPI) GetPosts(c *gin.Context) {
+	pageStr := strings.TrimSpace(c.Query("page"))
+	pageSizeStr := strings.TrimSpace(c.Query("pageSize"))
+
+	var page, pageSize int
+	var err error
+
+	if pageStr == "" {
+		page = 1
+	} else {
+		page, err = strconv.Atoi(pageStr)
+		if err != nil {
+			grenderer.Render(c, gin.H{"message": "invalid page parameter"}, http.StatusBadRequest)
+			return
+		}
+	}
+	if pageSizeStr == "" {
+		pageSize = 10
+	} else {
+		pageSize, err = strconv.Atoi(pageSizeStr)
+		if err != nil {
+			grenderer.Render(c, gin.H{"message": "invalid pageSize parameter"}, http.StatusBadRequest)
+			return
+		}
+	}
+
 	ctx, cancel := context.WithTimeout(c.Request.Context(), 5*time.Second)
 	defer cancel()
 
-	resp, statusCode := api.postService.GetPosts(ctx)
+	resp, statusCode := api.postService.GetPosts(ctx, page, pageSize)
 	grenderer.Render(c, resp, statusCode)
 }
 

example2/internal/repo/post.go

@@ -24,6 +24,8 @@ func NewPostRepo(conn *gorm.DB) *PostRepo {
 // PostRepository defines the contract for post-related operations.
 type PostRepository interface {
 	GetPosts(ctx context.Context) ([]model.Post, error)
+	ListPosts(ctx context.Context, limit, offset int) ([]model.Post, error)
+	CountPosts(ctx context.Context) (int64, error)
 	GetPost(ctx context.Context, postID uint64) (*model.Post, error)
 	GetPostsByUserID(ctx context.Context, userID uint64) ([]model.Post, error)
 	CreatePost(ctx context.Context, post *model.Post) error
@@ -45,6 +47,27 @@ func (r *PostRepo) GetPosts(ctx context.Context) ([]model.Post, error) {
 	return posts, nil
 }
 
+// ListPosts returns a paginated list of posts ordered by post_id descending.
+func (r *PostRepo) ListPosts(ctx context.Context, limit, offset int) ([]model.Post, error) {
+	var posts []model.Post
+	err := r.db.WithContext(ctx).
+		Order("post_id desc").
+		Limit(limit).
+		Offset(offset).
+		Find(&posts).Error
+	if err != nil {
+		return nil, err
+	}
+	return posts, nil
+}
+
+// CountPosts returns the total number of posts in the database.
+func (r *PostRepo) CountPosts(ctx context.Context) (int64, error) {
+	var total int64
+	err := r.db.WithContext(ctx).Model(&model.Post{}).Count(&total).Error
+	return total, err
+}
+
 // GetPost returns a post with the given postID from the database.
 func (r *PostRepo) GetPost(ctx context.Context, postID uint64) (*model.Post, error) {
 	var post model.Post

example2/internal/service/post.go

@@ -27,9 +27,22 @@ func NewPostService(postRepo repo.PostRepository, userRepo repo.UserRepository)
 	}
 }
 
-// GetPosts retrieves all posts.
-func (s *PostService) GetPosts(ctx context.Context) (httpResponse gmodel.HTTPResponse, httpStatusCode int) {
-	posts, err := s.postRepo.GetPosts(ctx)
+// GetPosts retrieves a paginated list of posts.
+func (s *PostService) GetPosts(ctx context.Context, page, pageSize int) (httpResponse gmodel.HTTPResponse, httpStatusCode int) {
+	// normalize pagination params
+	if page <= 0 {
+		page = 1
+	}
+	if pageSize <= 0 {
+		pageSize = 10
+	}
+	if pageSize > 100 {
+		pageSize = 100
+	}
+	offset := (page - 1) * pageSize
+
+	// get total count
+	total, err := s.postRepo.CountPosts(ctx)
 	if err != nil {
 		if errors.Is(err, context.Canceled) {
 			httpResponse.Message = "request canceled"
@@ -43,13 +56,46 @@ func (s *PostService) GetPosts(ctx context.Context) (httpResponse gmodel.HTTPRes
 		return
 	}
 
+	if total == 0 {
+		httpResponse.Message = "no post found"
+		httpStatusCode = http.StatusNotFound
+		return
+	}
+
+	// get paginated posts
+	posts, err := s.postRepo.ListPosts(ctx, pageSize, offset)
+	if err != nil {
+		if errors.Is(err, context.Canceled) {
+			httpResponse.Message = "request canceled"
+			httpStatusCode = http.StatusRequestTimeout
+			return
+		}
+
+		log.WithError(err).Error("GetPosts.s.2")
+		httpResponse.Message = "internal server error"
+		httpStatusCode = http.StatusInternalServerError
+		return
+	}
+
 	if len(posts) == 0 {
 		httpResponse.Message = "no post found"
 		httpStatusCode = http.StatusNotFound
 		return
 	}
 
-	httpResponse.Message = posts
+	hasNext := int64(page*pageSize) < total
+	hasPrevious := page > 1
+
+	result := map[string]any{
+		"hasNext":     hasNext,
+		"hasPrevious": hasPrevious,
+		"page":        page,
+		"pageSize":    pageSize,
+		"posts":       posts,
+		"total":       total,
+	}
+
+	httpResponse.Message = result
 	httpStatusCode = http.StatusOK
 	return
 }