Query: Convert IReadOnlyCollection.Count to Queryable.Count()

Resolves #26437
dotnet · Oct 28, 2021 · dd70313 · dd70313
1 parent 90f0808
commit dd70313
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Showing 2 changed files with 72 additions and 1 deletion.
diff --git a/src/EFCore/Query/Internal/NavigationExpandingExpressionVisitor.cs b/src/EFCore/Query/Internal/NavigationExpandingExpressionVisitor.cs
@@ -214,7 +214,10 @@ protected override Expression VisitMember(MemberExpression memberExpression)
                 && innerExpression != null
                 && memberExpression.Member.Name == nameof(ICollection<int>.Count)
                 && memberExpression.Expression.Type.GetInterfaces().Append(memberExpression.Expression.Type)
-                    .Any(e => e.IsGenericType && e.GetGenericTypeDefinition() == typeof(ICollection<>)))
+                    .Any(e => e.IsGenericType
+                        && (e.GetGenericTypeDefinition() is Type genericTypeDefinition
+                            && (genericTypeDefinition == typeof(ICollection<>)
+                                || genericTypeDefinition == typeof(IReadOnlyCollection<>)))))
             {
                 var innerQueryable = UnwrapCollectionMaterialization(innerExpression);
 

diff --git a/test/EFCore.Specification.Tests/Query/SimpleQueryTestBase.cs b/test/EFCore.Specification.Tests/Query/SimpleQueryTestBase.cs
@@ -324,5 +324,73 @@ public PhotoBlog()
 
             public int NumberOfPhotos { get; set; }
         }
+
+        [ConditionalTheory]
+        [MemberData(nameof(IsAsyncData))]
+        public virtual async Task Count_member_over_IReadOnlyCollection_works(bool async)
+        {
+            var contextFactory = await InitializeAsync<Context26433>(seed: c => c.Seed());
+            using var context = contextFactory.CreateContext();
+
+            var query = context.Authors
+                    .Select(a => new
+                    {
+                        BooksCount = a.Books.Count
+                    });
+
+            var authors = async
+                ? await query.ToListAsync()
+                : query.ToList();
+
+            Assert.Equal(3, Assert.Single(authors).BooksCount);
+        }
+
+        protected class Context26433 : DbContext
+        {
+            public Context26433(DbContextOptions options)
+                   : base(options)
+            {
+            }
+
+            public DbSet<Book26433> Books { get; set; }
+            public DbSet<Author26433> Authors { get; set; }
+
+            public void Seed()
+            {
+
+                base.Add(new Author26433
+                {
+                    FirstName = "William",
+                    LastName = "Shakespeare",
+                    Books = new List<Book26433>
+                        {
+                            new() {Title = "Hamlet"},
+                            new() {Title = "Othello"},
+                            new() {Title = "MacBeth"}
+                        }
+                });
+
+                SaveChanges();
+            }
+        }
+
+        protected class Author26433
+        {
+            [Key]
+            public int AuthorId { get; set; }
+            public string FirstName { get; set; }
+            public string LastName { get; set; }
+            public IReadOnlyCollection<Book26433> Books { get; set; }
+        }
+
+        protected class Book26433
+        {
+            [Key]
+            public int BookId { get; set; }
+            public string Title { get; set; }
+            public int AuthorId { get; set; }
+            public Author26433 Author { get; set; }
+        }
+
     }
 }