feat: add postDTO model validation middleware

Author: architxkumar

internal/middleware/validation.go

@@ -0,0 +1,52 @@
+package middleware
+
+import (
+	"Blogging-Platform-API/internal/model"
+	"context"
+	"encoding/json"
+	"io"
+	"log"
+	"net/http"
+)
+
+const PostKey = "post"
+
+func ValidatePostDTO(handler http.Handler) http.Handler {
+	return http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
+		requestBodyBytes, err := io.ReadAll(request.Body)
+		if err != nil || len(requestBodyBytes) == 0 {
+			log.Print("Error: Request Body cannot be empty")
+			http.Error(writer, "Request Body cannot be empty", http.StatusBadRequest)
+			return
+		}
+		var post model.PostDTO
+		err = json.Unmarshal(requestBodyBytes, &post)
+		if err != nil {
+			log.Print("Error: Unmarshalling request Body")
+			http.Error(writer, "Invalid request Body", http.StatusBadRequest)
+			return
+		}
+		if post.Title == "" {
+			log.Print("Error: Title field cannot be empty")
+			http.Error(writer, "Title field cannot be empty", http.StatusUnprocessableEntity)
+			return
+		}
+		if len(post.Title) > 255 {
+			log.Print("Error: Invalid title length ", len(post.Title))
+			http.Error(writer, "Title field is too big", http.StatusUnprocessableEntity)
+			return
+		}
+		if post.Content == "" {
+			log.Print("Error: Content field is empty")
+			http.Error(writer, "Content field is empty", http.StatusUnprocessableEntity)
+			return
+		}
+		if len(post.Category) >= 30 {
+			log.Print("Error: Category field is too big ", len(post.Category))
+			http.Error(writer, "Error: Category field is too big ", http.StatusUnprocessableEntity)
+			return
+		}
+		ctx := context.WithValue(request.Context(), PostKey, post)
+		handler.ServeHTTP(writer, request.WithContext(ctx))
+	})
+}

internal/model/post.go

@@ -13,3 +13,14 @@ type Post struct {
 	CreatedAt time.Time `json:"created_at"`
 	UpdatedAt time.Time `json:"updated_at"`
 }
+
+type PostDTO struct {
+	// length until 255
+	Title   string `json:"title"`
+	Content string `json:"content"`
+	// length until 30
+	Category  string    `json:"category"`
+	Tags      []string  `json:"tags"`
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+}

main.go

@@ -8,6 +8,6 @@ import (
 )
 
 func main() {
-	http.Handle("/posts", middleware.RequestIDGeneratorMiddleware(middleware.LoggingMiddleware(http.HandlerFunc(handler.TaskCreationHandler))))
+	http.Handle("POST /posts", middleware.RequestIDGeneratorMiddleware(middleware.LoggingMiddleware(middleware.ValidatePostDTO(http.HandlerFunc(handler.TaskCreationHandler)))))
 	log.Fatal(http.ListenAndServe(":8080", nil))
 }