Query: Convert List.Count to Queryable.Count() only for queryables

For collection scalar property preserve Count member as is. Resolves #19715
dotnet · Feb 7, 2020 · 3a91c13 · 3a91c13
1 parent 24b0c3c
commit 3a91c13
Show file tree

Hide file tree

Showing 3 changed files with 22 additions and 2 deletions.
diff --git a/src/EFCore/Query/Internal/NavigationExpandingExpressionVisitor.cs b/src/EFCore/Query/Internal/NavigationExpandingExpressionVisitor.cs
@@ -158,10 +158,13 @@ protected override Expression VisitMember(MemberExpression memberExpression)
             {
                 var innerQueryable = UnwrapCollectionMaterialization(innerExpression);
 
-                return Visit(
+                if (innerQueryable.Type.TryGetElementType(typeof(IQueryable<>)) != null)
+                {
+                    return Visit(
                     Expression.Call(
                         QueryableMethods.CountWithoutPredicate.MakeGenericMethod(innerQueryable.Type.TryGetSequenceType()),
                         innerQueryable));
+                }
             }
 
             var updatedExpression = (Expression)memberExpression.Update(innerExpression);

diff --git a/test/EFCore.InMemory.FunctionalTests/CustomConvertersInMemoryTest.cs b/test/EFCore.InMemory.FunctionalTests/CustomConvertersInMemoryTest.cs
@@ -30,6 +30,12 @@ public override void Collection_property_as_scalar_Any()
             base.Collection_property_as_scalar_Any();
         }
 
+        [ConditionalFact(Skip = "Issue#17050")]
+        public override void Collection_property_as_scalar_Count_member()
+        {
+            base.Collection_property_as_scalar_Count_member();
+        }
+
         [ConditionalFact(Skip = "Issue#17050")]
         public override void Collection_enum_as_string_Contains()
         {

diff --git a/test/EFCore.Specification.Tests/CustomConvertersTestBase.cs b/test/EFCore.Specification.Tests/CustomConvertersTestBase.cs
@@ -576,6 +576,17 @@ public virtual void Collection_property_as_scalar_Any()
                     .Message.Replace("\r", "").Replace("\n", ""));
         }
 
+        [ConditionalFact]
+        public virtual void Collection_property_as_scalar_Count_member()
+        {
+            using var context = CreateContext();
+            Assert.Equal(
+                @"The LINQ expression 'DbSet<CollectionScalar>    .Where(c => c.Tags.Count == 2)' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync(). See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.",
+                Assert.Throws<InvalidOperationException>(
+                    () => context.Set<CollectionScalar>().Where(e => e.Tags.Count == 2).ToList())
+                    .Message.Replace("\r", "").Replace("\n", ""));
+        }
+
         protected class CollectionScalar
         {
             public int Id { get; set; }
@@ -1000,7 +1011,7 @@ protected override void OnModelCreating(ModelBuilder modelBuilder, DbContext con
                         b.IndexedProperty(typeof(bool), "IndexerVisible").HasConversion(new BoolToStringConverter("Nay", "Aye"));
 
                         b.HasData(
-                            new 
+                            new
                             {
                                 BlogId = 1,
                                 Url = "http://blog.com",