Query: Block queries with AsSplitQuery when collection was not split

Resolves #22067

src/EFCore.Relational/Properties/RelationalStrings.resx

@@ -1,17 +1,17 @@
 <?xml version="1.0" encoding="utf-8"?>
 <root>
-  <!--
-    Microsoft ResX Schema
-
+  <!-- 
+    Microsoft ResX Schema 
+    
     Version 2.0
-
-    The primary goals of this format is to allow a simple XML format
-    that is mostly human readable. The generation and parsing of the
-    various data types are done through the TypeConverter classes
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
     associated with the data types.
-
+    
     Example:
-
+    
     ... ado.net/XML headers & schema ...
     <resheader name="resmimetype">text/microsoft-resx</resheader>
     <resheader name="version">2.0</resheader>
@@ -26,36 +26,36 @@
         <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
         <comment>This is a comment</comment>
     </data>
-
-    There are any number of "resheader" rows that contain simple
+                
+    There are any number of "resheader" rows that contain simple 
     name/value pairs.
-
-    Each data row contains a name, and value. The row also contains a
-    type or mimetype. Type corresponds to a .NET class that support
-    text/value conversion through the TypeConverter architecture.
-    Classes that don't support this are serialized and stored with the
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
     mimetype set.
-
-    The mimetype is used for serialized objects, and tells the
-    ResXResourceReader how to depersist the object. This is currently not
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
     extensible. For a given mimetype the value must be set accordingly:
-
-    Note - application/x-microsoft.net.object.binary.base64 is the format
-    that the ResXResourceWriter will generate, however the reader can
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
     read any of the formats listed below.
-
+    
     mimetype: application/x-microsoft.net.object.binary.base64
-    value   : The object must be serialized with
+    value   : The object must be serialized with 
             : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
             : and then encoded with base64 encoding.
-
+    
     mimetype: application/x-microsoft.net.object.soap.base64
-    value   : The object must be serialized with
+    value   : The object must be serialized with 
             : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
             : and then encoded with base64 encoding.
 
     mimetype: application/x-microsoft.net.object.bytearray.base64
-    value   : The object must be serialized into a byte array
+    value   : The object must be serialized into a byte array 
             : using a System.ComponentModel.TypeConverter
             : and then encoded with base64 encoding.
     -->
@@ -765,4 +765,7 @@
   <data name="VisitChildrenMustBeOverridden" xml:space="preserve">
     <value>VisitChildren must be overridden in class deriving from SqlExpression.</value>
   </data>
+  <data name="UnableToSplitCollectionProjectionInSplitQuery" xml:space="preserve">
+    <value>The query has been configured to use '{splitQueryEnumValue}' and contains collection in projection, which was not split into separate query. Please remove '{splitQueryMethodName}' if applied or add '{singleQueryMethodName}' to the query.</value>
+  </data>
 </root>

src/EFCore.Relational/Query/Internal/CollectionJoinApplyingExpressionVisitor.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using System.Linq.Expressions;
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore.Diagnostics;
@@ -68,36 +69,26 @@ protected override Expression VisitExtension(Expression extensionExpression)
                     selectExpression.PushdownIntoSubquery();
                 }
 
-                if (_splitQuery)
-                {
-                    var splitCollectionShaperExpression = (RelationalSplitCollectionShaperExpression)selectExpression.ApplyCollectionJoin(
-                        projectionBindingExpression.Index.Value,
-                        collectionId,
-                        collectionShaperExpression.InnerShaper,
-                        collectionShaperExpression.Navigation,
-                        collectionShaperExpression.ElementType,
-                        _splitQuery);
+                var innerShaper = Visit(collectionShaperExpression.InnerShaper);
 
-                    var innerShaper = Visit(splitCollectionShaperExpression.InnerShaper);
+                var collectionJoin = selectExpression.ApplyCollectionJoin(
+                    projectionBindingExpression.Index.Value,
+                    collectionId,
+                    innerShaper,
+                    collectionShaperExpression.Navigation,
+                    collectionShaperExpression.ElementType,
+                    _splitQuery);
 
-                    return splitCollectionShaperExpression.Update(
-                        splitCollectionShaperExpression.ParentIdentifier,
-                        splitCollectionShaperExpression.ChildIdentifier,
-                        splitCollectionShaperExpression.SelectExpression,
-                        innerShaper);
-                }
-                else
+                if (_splitQuery
+                    && collectionJoin == null)
                 {
-                    var innerShaper = Visit(collectionShaperExpression.InnerShaper);
-
-                    return selectExpression.ApplyCollectionJoin(
-                        projectionBindingExpression.Index.Value,
-                        collectionId,
-                        innerShaper,
-                        collectionShaperExpression.Navigation,
-                        collectionShaperExpression.ElementType,
-                        _splitQuery);
+                    throw new InvalidOperationException(RelationalStrings.UnableToSplitCollectionProjectionInSplitQuery(
+                        $"{nameof(QuerySplittingBehavior)}.{QuerySplittingBehavior.SplitQuery}",
+                        nameof(RelationalQueryableExtensions.AsSplitQuery),
+                        nameof(RelationalQueryableExtensions.AsSingleQuery)));
                 }
+
+                return collectionJoin;
             }
 
             return extensionExpression is ShapedQueryExpression shapedQueryExpression

src/EFCore.Relational/Query/SqlExpressions/SelectExpression.cs

@@ -1330,6 +1330,13 @@ public Expression ApplyCollectionJoin(
 
             if (splitQuery)
             {
+                var containsReferenceToOuter = new SelectExpressionCorrelationFindingExpressionVisitor(this)
+                   .ContainsOuterReference(innerSelectExpression);
+                if (containsReferenceToOuter)
+                {
+                    return null;
+                }
+
                 var parentIdentifier = GetIdentifierAccessor(_identifier).Item1;
                 innerSelectExpression.ApplyProjection();
 

test/EFCore.Relational.Specification.Tests/Query/ComplexNavigationsQueryRelationalTestBase.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Linq;
 using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.EntityFrameworkCore.TestModels.ComplexNavigationsModel;
 using Microsoft.EntityFrameworkCore.TestUtilities;
 using Xunit;
@@ -482,6 +483,51 @@ public virtual async Task Filtered_include_calling_methods_directly_on_parameter
                         .AsSplitQuery()))).Message;
         }
 
+        [ConditionalTheory]
+        [MemberData(nameof(IsAsyncData))]
+        public virtual async Task Projecting_collection_with_FirstOrDefault_split_throws(bool async)
+        {
+            Assert.Equal(
+                RelationalStrings.UnableToSplitCollectionProjectionInSplitQuery(
+                    "QuerySplittingBehavior.SplitQuery", "AsSplitQuery", "AsSingleQuery"),
+                (await Assert.ThrowsAsync<InvalidOperationException>(
+                    () => AssertFirstOrDefault(
+                        async,
+                        ss => ss.Set<Level1>()
+                                .AsSplitQuery()
+                                .Select(e => new
+                                {
+                                    e.Id,
+                                    Level2s = e.OneToMany_Optional1.ToList()
+                                }),
+                        predicate: l => l.Id == 1,
+                        asserter: (e, a) =>
+                        {
+                            Assert.Equal(e.Id, a.Id);
+                            AssertCollection(e.Level2s, a.Level2s);
+                        }))).Message);
+        }
+
+        [ConditionalTheory]
+        [MemberData(nameof(IsAsyncData))]
+        public virtual Task Projecting_collection_with_FirstOrDefault_without_split_works(bool async)
+        {
+            return AssertFirstOrDefault(
+                async,
+                ss => ss.Set<Level1>()
+                        .Select(e => new
+                        {
+                            e.Id,
+                            Level2s = e.OneToMany_Optional1.ToList()
+                        }),
+                predicate: l => l.Id == 1,
+                asserter: (e, a) =>
+                {
+                    Assert.Equal(e.Id, a.Id);
+                    AssertCollection(e.Level2s, a.Level2s);
+                });
+        }
+
         protected virtual bool CanExecuteQueryString => false;
 
         protected override QueryAsserter CreateQueryAsserter(TFixture fixture)

test/EFCore.SqlServer.FunctionalTests/Query/ComplexNavigationsQuerySqlServerTest.cs

@@ -5833,6 +5833,21 @@ ELSE [l1].[Name]
 END IS NULL");
         }
 
+        public override async Task Projecting_collection_with_FirstOrDefault_without_split_works(bool async)
+        {
+            await base.Projecting_collection_with_FirstOrDefault_without_split_works(async);
+
+            AssertSql(
+                @"SELECT [t].[Id], [l0].[Id], [l0].[Date], [l0].[Level1_Optional_Id], [l0].[Level1_Required_Id], [l0].[Name], [l0].[OneToMany_Optional_Inverse2Id], [l0].[OneToMany_Optional_Self_Inverse2Id], [l0].[OneToMany_Required_Inverse2Id], [l0].[OneToMany_Required_Self_Inverse2Id], [l0].[OneToOne_Optional_PK_Inverse2Id], [l0].[OneToOne_Optional_Self2Id]
+FROM (
+    SELECT TOP(1) [l].[Id]
+    FROM [LevelOne] AS [l]
+    WHERE [l].[Id] = 1
+) AS [t]
+LEFT JOIN [LevelTwo] AS [l0] ON [t].[Id] = [l0].[OneToMany_Optional_Inverse2Id]
+ORDER BY [t].[Id], [l0].[Id]");
+        }
+
         private void AssertSql(params string[] expected) => Fixture.TestSqlLoggerFactory.AssertBaseline(expected);
     }
 }