backend: frontend: add file load feature

added a feature to load existing json files and load the containing monsters

handlers/load_file_handler.go

@@ -0,0 +1,46 @@
+package handlers
+
+import (
+	"ddServer/model"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+)
+
+func LoadFileHandler(monsters *[]model.Monster) http.HandlerFunc {
+	log.Print("LoadFileHandler called")
+	return func(w http.ResponseWriter, r *http.Request) {
+		r.ParseMultipartForm(10 << 20) // 10 MB limit
+
+		// Get the file from the request
+		file, _, err := r.FormFile("uploadFile")
+		if err != nil {
+			http.Error(w, "Error retrieving file", http.StatusBadRequest)
+			return
+		}
+		defer file.Close()
+
+		// Parse the file content
+		decoder := json.NewDecoder(file)
+		var loadedChars model.Character
+		err = decoder.Decode(&loadedChars)
+		if err != nil {
+			http.Error(w, "Error decoding file content", http.StatusInternalServerError)
+			return
+		}
+
+		// Lock the Monsters slice and append the loaded monsters, then unlock the slice
+		mu.Lock()
+		defer mu.Unlock()
+
+		// Assuming 'loadedChars' contains an array of Monster objects
+		for _, monster := range loadedChars.Monster {
+			*monsters = append(*monsters, monster)
+		}
+
+		fmt.Printf("%v\n", monsters)
+		// Send a success response
+		http.Redirect(w, r, "/monsterTable", http.StatusTemporaryRedirect)
+	}
+}