implementing pagination on posts

Author: Euler-B

database/postgres.go

@@ -121,3 +121,28 @@ func (repo *PostgresRepository) DeletePost(ctx context.Context, id string, userI
 		id, userId)
 	return err
 }
+
+func (repo *PostgresRepository) ListPost(ctx context.Context, page uint64) ([]*models.Post, error){
+	rows, err := repo.db.QueryContext(ctx, 
+		"SELECT id, post_content, user_id, created_at FROM posts LIMIT $1 OFFSET $2", 2, page * 2)
+	if err != nil {
+		return nil, err
+	}
+	defer func(){
+		err = rows.Close()
+		if err != nil {
+			log.Fatal(err)
+		}
+	}()
+	var posts []*models.Post
+	for rows.Next() {
+		var post = models.Post{}
+		if err = rows.Scan(&post.Id, &post.PostContent, &post.UserId, &post.CreatedAt); err == nil {
+			posts = append(posts, &post)	
+		}
+	}
+	if err = rows.Err(); err != nil {
+		return nil, err
+	}
+	return posts, nil 
+}

handlers/posts.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"net/http"
 	"strings"
+	"strconv"
 
 	"github.com/golang-jwt/jwt/v4"
 	"github.com/gorilla/mux"
@@ -152,4 +153,26 @@ func DeletePostHandler(s server.Server) http.HandlerFunc {
 				return
 			}
 	}
+}
+
+func ListPostHandler(s server.Server) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request){
+		var err error
+		pageStr := r.URL.Query().Get("page")
+		var page uint64
+		if pageStr != "" {
+			page, err = strconv.ParseUint(pageStr, 10, 64)
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusBadRequest)
+				return
+			}
+		}
+		posts, err := repository.ListPost(r.Context(), page)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(posts)
+	}
 }

main.go

@@ -50,4 +50,5 @@ func BindRoutes(s server.Server, r *mux.Router) {
 	r.HandleFunc("/posts/{id}", handlers.GetPostByIdHandler(s)).Methods(http.MethodGet)
 	r.HandleFunc("/posts/{id}", handlers.UpdatePostHandler(s)).Methods(http.MethodPut)
 	r.HandleFunc("/posts/{id}", handlers.DeletePostHandler(s)).Methods(http.MethodDelete)
+	r.HandleFunc("/posts", handlers.ListPostHandler(s)).Methods(http.MethodGet)
 }

repository/repository.go

@@ -15,6 +15,7 @@ type Repository interface {
 	GetPostById(ctx context.Context, id string) (*models.Post, error)
 	UpdatePost(ctx context.Context, post *models.Post) error
 	DeletePost(ctx context.Context, id string, userId string) error
+	ListPost(ctx context.Context, page uint64) ([]*models.Post, error)
 	Close() error
 }
 
@@ -54,4 +55,8 @@ func UpdatePost(ctx context.Context, post *models.Post) error {
 
 func DeletePost(ctx context.Context, id string, userId string) error {
 	return implementation.DeletePost(ctx, id, userId) 
+}
+
+func ListPost(ctx context.Context, page uint64) ([]*models.Post, error) {
+	return implementation.ListPost(ctx, page)
 }