NullReferenceException when accessing navigation property with compiled models and ambiguous type names

[devbased]

Description

The issue arises when using Compiled Models. Types are not identified by their 'FullName'. Thus, if user code has a custom type with the same name as a generated type, a runtime NullReferenceException will occur when attempting to access a navigation property with lazy-loading enabled.

Steps To Reproduce

1. Create a .NET 7 project and install packages:
   • Microsoft.EntityFrameworkCore.Design 7.0.11
   • Microsoft.EntityFrameworkCore.Proxies 7.0.11
   • Microsoft.EntityFrameworkCore.Sqlite 7.0.11
2. Add EF Core model classes A and B with a navigation property between them
3. Create a custom AEntityType enum in a separate namespace
4. Add property public AEntityType EntityType { get; set; } to B
5. Enable compiled models and lazy loading proxies in DbContext configuration
6. Seed database and retrieve an A entity
7. Attempt to access the B navigation property
8. A NullReferenceException will occur when accessing B

Code Sample

using CompiledModelEntityNameAmbiguityBug.CompiledModels; 
using Microsoft.EntityFrameworkCore;
using AEntityType = Enums.AEntityType;

await using var dbContext = new TestContext();
await dbContext.Database.EnsureCreatedAsync();

var a = await dbContext.Set<A>().FirstAsync(x => x.AId == 1);

// attempt to access B - NullReferenceException  
Console.WriteLine(a.B!.EntityType);

public class TestContext : DbContext
{
  /// <inheritdoc />
  protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) 
  {
    base.OnConfiguring(optionsBuilder);

    optionsBuilder
      .UseSqlite("Data Source=test.db")
      .UseModel(TestContextModel.Instance)
      .UseLazyLoadingProxies();
  }

  /// <inheritdoc />
  protected override void OnModelCreating(ModelBuilder modelBuilder)
  {
    base.OnModelCreating(modelBuilder);

    modelBuilder.Entity<A>().HasData(new A { AId = 1, }); 
    modelBuilder.Entity<B>().HasData(new B { AId = 1, BId = 1, EntityId = 1, EntityType = AEntityType.Foo, });
  }
}

public class A
{
  public int AId { get; set; }

  public virtual B? B { get; set; } 
}

public class B  
{
  public int BId { get; set; }
  public int AId { get; set; }
  public int EntityId { get; set; }
  public AEntityType EntityType { get; set; } 
}

namespace Enums
{
  public enum AEntityType
  {
    Foo,
  }
}

Stack Trace

Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.CreateGetValueExpression(ParameterExpression dbDataReader, Int32 index, Boolean nullable, RelationalTypeMapping typeMapping, Type type, IPropertyBase property)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
   at System.Linq.Expressions.ExpressionVisitor.VisitBinary(BinaryExpression node)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.VisitBinary(BinaryExpression binaryExpression)
   at System.Dynamic.Utils.ExpressionVisitorUtils.VisitBlockExpressions(ExpressionVisitor visitor, BlockExpression block)
   at System.Linq.Expressions.ExpressionVisitor.VisitBlock(BlockExpression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitUnary(UnaryExpression node)
   at System.Dynamic.Utils.ExpressionVisitorUtils.VisitBlockExpressions(ExpressionVisitor visitor, BlockExpression block)
   at System.Linq.Expressions.ExpressionVisitor.VisitBlock(BlockExpression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitSwitchCase(SwitchCase node)
   at System.Linq.Expressions.ExpressionVisitor.Visit[T](ReadOnlyCollection`1 nodes, Func`2 elementVisitor)
   at System.Linq.Expressions.ExpressionVisitor.VisitSwitch(SwitchExpression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitBinary(BinaryExpression node)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.VisitBinary(BinaryExpression binaryExpression)
   at System.Dynamic.Utils.ExpressionVisitorUtils.VisitBlockExpressions(ExpressionVisitor visitor, BlockExpression block)
   at System.Linq.Expressions.ExpressionVisitor.VisitBlock(BlockExpression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitConditional(ConditionalExpression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitConditional(ConditionalExpression node)
   at System.Dynamic.Utils.ExpressionVisitorUtils.VisitBlockExpressions(ExpressionVisitor visitor, BlockExpression block)
   at System.Linq.Expressions.ExpressionVisitor.VisitBlock(BlockExpression node)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.ProcessShaper(Expression shaperExpression, RelationalCommandCache& relationalCommandCache, IReadOnlyList`1& readerColumns, LambdaExpression& relatedDataLoaders, Int32& collectionId)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.VisitShapedQuery(ShapedQueryExpression shapedQueryExpression)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](Expression query, Boolean async)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass9_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 compiler)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1.GetEnumerator()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.Load[TSource](IQueryable`1 source)
   at Microsoft.EntityFrameworkCore.Internal.EntityFinder`1.Load(INavigation navigation, InternalEntityEntry entry)
   at Microsoft.EntityFrameworkCore.ChangeTracking.ReferenceEntry.Load()
   at Microsoft.EntityFrameworkCore.Infrastructure.Internal.LazyLoader.Load(Object entity, String navigationName)
   at Microsoft.EntityFrameworkCore.Proxies.Internal.LazyLoadingInterceptor.Intercept(IInvocation invocation)
   at Castle.DynamicProxy.AbstractInvocation.Proceed()
   at Castle.Proxies.AProxy.get_B()
   at Program.<Main>$(String[] args) in Program.cs:line 11
   at Program.<Main>$(String[] args) in Program.cs:line 11
   at Program.<Main>(String[] args)

General Info

EF Core version: 7.0.11 Database provider: Microsoft.EntityFrameworkCore.Sqlite

Target framework: .NET 7.0 Operating system: Windows 10 IDE: JetBrains Rider 2023.2

[devbased]

I thought it is a rare case, but in the project I work on, it turned out that many entities have the same name but are located in different namespaces. There are also some collisions with System (for example, we have a domain entity called TimeZone) 😔

[ajcvickers]

Duplicate of #27203