implement a DTO - Data Transfer Object; it makes sense to me to call …

…it the user-facing version of the object. Purpose: prevent over-posting, hide properties that clients shouldn't see, omit properties to reduce size, flatten object graphs (can be more convenient for clients)

TodoApi/Program.cs

@@ -8,33 +8,42 @@
 app.MapGet("/", () => "Hello World!");
 
 app.MapGet("/todoitems", async (TodoDb db) =>
-    await db.Todos.ToListAsync());
+    await db.Todos.Select(x => new TodoItemDTO(x)).ToListAsync());
 
-app.MapGet("/todoitems/complete", async (TodoDb db) =>
-    await db.Todos.Where(t => t.IsComplete).ToListAsync());
+// These lines not included in step Prevent over-posting
+// TODO Can I make them right?
+
+//app.MapGet("/todoitems/complete", async (TodoDb db) =>
+//    await db.Todos.Where(t => t.IsComplete).ToListAsync());
 
 app.MapGet("/todoitems/{id}", async (int id, TodoDb db) =>
     await db.Todos.FindAsync(id)
         is Todo todo
-            ? Results.Ok(todo)
+            ? Results.Ok(new TodoItemDTO(todo))
             : Results.NotFound());
 
-app.MapPost("/todoitems", async (Todo todo, TodoDb db) =>
+app.MapPost("/todoitems", async (TodoItemDTO todoItemDTO, TodoDb db) =>
 {
-    db.Todos.Add(todo);
+    var todoItem = new Todo
+    {
+        IsComplete = todoItemDTO.IsComplete,
+        Name = todoItemDTO.Name
+    };
+
+    db.Todos.Add(todoItem);
     await db.SaveChangesAsync();
 
-    return Results.Created($"/todoitems/{todo.Id}", todo);
+    return Results.Created($"/todoitems/{todoItem.Id}", new TodoItemDTO(todoItem));
 });
 
-app.MapPut("/todoitems/{id}", async (int id, Todo inputTodo, TodoDb db) =>
+app.MapPut("/todoitems/{id}", async (int id, TodoItemDTO todoItemDTO, TodoDb db) =>
 {
     var todo = await db.Todos.FindAsync(id);
 
     if (todo is null) return Results.NotFound();
 
-    todo.Name = inputTodo.Name;
-    todo.IsComplete = inputTodo.IsComplete;
+    todo.Name = todoItemDTO.Name;
+    todo.IsComplete = todoItemDTO.IsComplete;
 
     await db.SaveChangesAsync();
 
@@ -47,22 +56,33 @@ is Todo todo
     {
         db.Todos.Remove(todo);
         await db.SaveChangesAsync();
-        return Results.Ok(todo);
+        return Results.Ok(new TodoItemDTO(todo));
     }
 
     return Results.NotFound();
 });
 
 app.Run();
 
-class Todo
+public class Todo
 {
     public int Id { get; set; }
     public string? Name { get; set; }
     public bool IsComplete { get; set; }
     public string? Secret { get; set; }
 }
 
+public class TodoItemDTO
+{
+    public int Id { get; set; }
+    public string? Name { get; set; }
+    public bool IsComplete { get; set; }
+
+    public TodoItemDTO() { }
+    public TodoItemDTO(Todo todoItem) =>
+    (Id, Name, IsComplete) = (todoItem.Id, todoItem.Name, todoItem.IsComplete);
+}
+
 class TodoDb : DbContext
 {
     public TodoDb(DbContextOptions<TodoDb> options)