A few cleanups based on experiment with generics

Author: farlee2121

Accessors.DatabaseAccessors/TodoItemAccessor.cs

@@ -54,7 +54,7 @@ public SaveResult<TodoItem> SaveTodoItem(TodoItem todoItem)
             {
                 TodoItemDTO dbModel = mapper.ContractToModel(todoItem);
 
-                if(todoItem.Id == Id.Default)
+                if(todoItem.Id.IsDefault())
                 {
                     db.TodoItems.Add(dbModel);
                 }

Accessors.DatabaseAccessors/TodoListAccessor.cs

@@ -71,7 +71,7 @@ public SaveResult<TodoList> SaveTodoList(TodoList todoList)
             {
                 TodoListDTO dbModel = mapper.ContractToModel(todoList);
 
-                if (todoList.Id == Id.Default)
+                if (todoList.Id.IsDefault())
                 {
                     db.TodoLists.Add(dbModel);
                 }

Shared.DataContracts/Id.cs

@@ -4,24 +4,30 @@
 
 namespace Shared.DataContracts
 {
-    public struct Id : IComparable, IComparable<Id>, IEquatable<Id>, IFormattable
+    public struct Id : IComparable, IComparable<Id>, IEquatable<Id>
     {
-        // this would also work genericly
-        // https://stackoverflow.com/questions/5377237/strongly-typing-id-values-in-c-sharp
         private readonly Guid _guid;
-        private static readonly Guid _default = Guid.Empty;
+        private static readonly Guid _default = default(Guid);
 
         public Id(Guid? guid)
         {
-            _guid = guid ?? Guid.Empty;
+            _guid = guid ?? _default;
         }
 
-        public static readonly Id Default = new Id(Guid.Empty);
+        public bool IsDefault()
+        {
+            return this._guid.Equals(_default);
+        }
+
+        public static Id Default()
+        { 
+            return new Id(_default);
+        }
 
         public static Id New()
         {
             return new Id(Guid.NewGuid());
-        } 
+        }
 
         public static explicit operator Id(Guid guid)
         {
@@ -40,7 +46,7 @@ public override bool Equals(object obj)
 
         public int CompareTo(object obj)
         {
-            if(obj is Id)
+            if (obj is Id)
             {
                 return this.CompareTo((Id)obj);
             }
@@ -64,10 +70,6 @@ public override string ToString()
         {
             return _guid.ToString();
         }
-        public string ToString(string format, IFormatProvider formatProvider)
-        {
-            return _guid.ToString(format, formatProvider);
-        }
 
         public override int GetHashCode()
         {