First attempt at splitting the Go code into seperate files to clean things up.

category.go

@@ -0,0 +1,40 @@
+package main
+
+type Category struct {
+	Id   int32  `json:"id"`
+	Name string `json:"name"`
+}
+
+type Subcategory struct {
+	Id         int32  `json:"id"`
+	Name       string `json:"name"`
+	CategoryId int32  `json:"categoryId"`
+}
+
+func getAllCategories() []Category {
+	db := getSQLConnection()
+
+	defer db.Close()
+
+	rows, err := db.Query("SELECT * FROM category;")
+
+	if err != nil {
+		panic(err)
+	}
+
+	defer rows.Close()
+
+	var categories []Category
+
+	for rows.Next() {
+		var category Category
+
+		if err = rows.Scan(&category.Id, &category.Name); err != nil {
+			println(err.Error())
+		}
+
+		categories = append(categories, category)
+	}
+
+	return categories
+}