Fix order by

docs/en/Tutorials/Part-10.md

@@ -326,6 +326,7 @@ Open the `BookAppService` interface in the `Books` folder of the `Acme.BookStore
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Linq.Dynamic.Core;
 using System.Threading.Tasks;
 using Acme.BookStore.Authors;
 using Acme.BookStore.Permissions;
@@ -387,23 +388,17 @@ namespace Acme.BookStore.Books
 
         public override async Task<PagedResultDto<BookDto>> GetListAsync(PagedAndSortedResultRequestDto input)
         {
-            //Set a default sorting, if not provided
-            if (input.Sorting.IsNullOrWhiteSpace())
-            {
-                input.Sorting = nameof(Book.Name);
-            }
-            
             //Get the IQueryable<Book> from the repository
             var queryable = await Repository.GetQueryableAsync();
 
             //Prepare a query to join books and authors
             var query = from book in queryable
                 join author in _authorRepository on book.AuthorId equals author.Id
-                orderby input.Sorting //TODO: Can not sort like that!
                 select new {book, author};
 
             //Paging
             query = query
+                .OrderBy(NormalizeSorting(input.Sorting))
                 .Skip(input.SkipCount)
                 .Take(input.MaxResultCount);
 
@@ -435,6 +430,25 @@ namespace Acme.BookStore.Books
                 ObjectMapper.Map<List<Author>, List<AuthorLookupDto>>(authors)
             );
         }
+
+        private static string NormalizeSorting(string sorting)
+        {
+            if (sorting.IsNullOrEmpty())
+            {
+                return $"book.{nameof(Book.Name)}";
+            }
+
+            if (sorting.Contains("authorName", StringComparison.OrdinalIgnoreCase))
+            {
+                return sorting.Replace(
+                    "authorName",
+                    "author.Name", 
+                    StringComparison.OrdinalIgnoreCase
+                );
+            }
+
+            return $"book.{sorting}";
+        }
     }
 }
 ```