[release/8.0] Do extra processing for init-only fields (#32342) (#32355)

Fixes #32310

Author: ajcvickers

src/EFCore.Relational/Query/RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.cs

@@ -16,6 +16,9 @@ public partial class RelationalShapedQueryCompilingExpressionVisitor
 {
     private sealed partial class ShaperProcessingExpressionVisitor : ExpressionVisitor
     {
+        public static readonly bool UseOldBehavior32310 =
+            AppContext.TryGetSwitch("Microsoft.EntityFrameworkCore.Issue32310", out var enabled32310) && enabled32310;
+
         /// <summary>
         ///     Reading database values
         /// </summary>
@@ -2063,7 +2066,10 @@ protected override Expression VisitBinary(BinaryExpression node)
                                     OrElse(
                                         ReferenceEqual(currentVariable, Constant(null)),
                                         ReferenceEqual(parameter, Constant(null))),
-                                    MakeBinary(node.NodeType, node.Left, parameter),
+                                    !UseOldBehavior32310
+                                    && node is { NodeType: ExpressionType.Assign, Left: MemberExpression leftMemberExpression }
+                                        ? leftMemberExpression.Assign(parameter)
+                                        : MakeBinary(node.NodeType, node.Left, parameter),
                                     Call(
                                         PopulateListMethod.MakeGenericMethod(property.ClrType.TryGetElementType(typeof(IEnumerable<>))!),
                                         parameter,

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

@@ -8,6 +8,70 @@ public abstract class JsonQueryAdHocTestBase : NonSharedModelTestBase
     protected override string StoreName
         => "JsonQueryAdHocTest";
 
+    #region 32310
+
+    [ConditionalTheory]
+    [MemberData(nameof(IsAsyncData))]
+    public virtual async Task Contains_on_nested_collection_with_init_only_navigation(bool async)
+    {
+        var contextFactory = await InitializeAsync<MyContext32310>(seed: Seed32310);
+        await using var context = contextFactory.CreateContext();
+
+        var query = context.Pubs
+            .Where(u => u.Visits.DaysVisited.Contains(new DateOnly(2023, 1, 1)));
+
+        var result = async
+            ? await query.FirstOrDefaultAsync()!
+            : query.FirstOrDefault()!;
+
+        Assert.Equal("FBI", result.Name);
+        Assert.Equal(new DateOnly(2023, 1, 1), result.Visits.DaysVisited.Single());
+    }
+
+    protected virtual void Seed32310(MyContext32310 context)
+    {
+        var user = new Pub32310
+        {
+            Name = "FBI",
+            Visits = new Visits32310
+            {
+                LocationTag = "tag",
+                DaysVisited = new List<DateOnly> { new(2023, 1, 1) }
+            }
+        };
+
+        context.Add(user);
+        context.SaveChanges();
+    }
+
+    protected class MyContext32310 : DbContext
+    {
+        public MyContext32310(DbContextOptions options)
+            : base(options)
+        {
+        }
+
+        public DbSet<Pub32310> Pubs => Set<Pub32310>();
+
+        protected override void OnModelCreating(ModelBuilder modelBuilder)
+            => modelBuilder.Entity<Pub32310>(b => { b.OwnsOne(e => e.Visits).ToJson(); });
+    }
+
+    public class Pub32310
+    {
+        public int Id { get; set; }
+        public required string Name { get; set; }
+        public Visits32310 Visits { get; set; } = null!;
+    }
+
+    public class Visits32310
+    {
+        public string LocationTag { get; set; }
+        public required List<DateOnly> DaysVisited { get; init; }
+    }
+
+    #endregion
+
     #region 29219
 
     [ConditionalTheory]
@@ -893,7 +957,7 @@ public class MyJsonEntityLazyLoadingProxies
     }
 
     #endregion
-    
+
     #region NotICollection
 
     [ConditionalTheory]