Cosmos: Owned entity type collection gets wrongly projected out as null when inside an anonymous object projection

[devbrsa]

Description:

When attempting to project a query result from Cosmos DB using Entity Framework Core, a System.NullReferenceException occurs with the stack trace pointing to lambda_method6.

Related Issues:

Issue related from OData: OData/AspNetCoreOData#1027

Environment:

• EF Core Package: Microsoft.EntityFrameworkCore.Cosmos
• EF Core Version: 6.0.21
• Database provider: Microsoft.EntityFrameworkCore.Cosmos
• Target framework: .NET 6.0
• IDE: (e.g. Visual Studio 2022 17.6)
• Operating System: Windows 10

Steps to Reproduce:

using Microsoft.EntityFrameworkCore;

var options = new DbContextOptionsBuilder<CosmosDbContext>()
    .UseCosmos("AccountEndpoint=https://localhost:8081/;AccountKey=C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==", "DummyDb")
    .Options;

using var context = new CosmosDbContext(options);
var employeeList = context.Employee.Select(x => new EmployeeDTO { Id = x.id, Emails = x.User.Emails }).ToList();

public class CosmosDbContext : DbContext
{
    public CosmosDbContext(DbContextOptions<CosmosDbContext> options) : base(options)
    {
    }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking);
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<RootObject>().ToContainer("DummyContainer");
        modelBuilder.Entity<RootObject>().HasNoDiscriminator();
    }

    public DbSet<RootObject> Employee { get; set; }

}

public class RootObject
{
    public string id { get; set; }
    public User User { get; set; }
    public string _rid { get; set; }
    public string _self { get; set; }
    public string _etag { get; set; }
    public string _attachments { get; set; }
    public int _ts { get; set; }
}

public class User
{
    public string Name { get; set; }
    public ICollection<Emails> Emails { get; set; }
}

public class Emails
{
    public string EmailAdress { get; set; }
    public string Type { get; set; }
}

public class EmployeeDTO
{
    public string Id { get; set; }
    public ICollection<Emails> Emails { get; set; }
}

Cosmos document representation:

{
    "id": "1",
    "User": {
        "Name": "John",
        "Emails": [
            {
                "EmailAdress": "john@1.com",
                "Type": "A"
            },
            {
                "EmailAdress": "john@2.com",
                "Type": "B"
            }
        ]
    },
    "_rid": "jqYgAN5HGIMBAAAAAAAAAA==",
    "_self": "dbs/jqYgAA==/colls/jqYgAN5HGIM=/docs/jqYgAN5HGIMBAAAAAAAAAA==/",
    "_etag": "\"00000000-0000-0000-e557-09ab7b4901d9\"",
    "_attachments": "attachments/",
    "_ts": 1694508997
}

Expected Behavior:

I expected to successfully project a query result from Cosmos DB using Entity Framework Core without encountering any exceptions.

Actual Behavior:

While attempting to project a query result from Cosmos DB using Entity Framework Core, I encountered a System.NullReferenceException with the following stack trace:

System.NullReferenceException: Object reference not set to an instance of an object.
   at lambda_method6(Closure , QueryContext , JObject )
   at Microsoft.EntityFrameworkCore.Cosmos.Query.Internal.CosmosShapedQueryCompilingExpressionVisitor.QueryingEnumerable`1.Enumerator.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Program.<Main>$(String[] args) in D:\Repos\CosmosBug\CosmosBug\Program.cs:line 8

[devbrsa]

Configuring the model builder like:

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<RootObject>().ToContainer("DummyContainer");
        modelBuilder.Entity<RootObject>().HasNoDiscriminator();

        modelBuilder.Entity<RootObject>().OwnsOne(r => r.User, user =>
        {
            user.Property(u => u.Name);
            user.OwnsMany(u => u.Emails);
        });
    }

The exception is:

System.InvalidOperationException: variable 'jObject1' of type 'Newtonsoft.Json.Linq.JObject' referenced from scope '', but it is not defined
   at System.Linq.Expressions.Compiler.VariableBinder.Reference(ParameterExpression node, VariableStorageKind storage)
   at System.Linq.Expressions.Compiler.VariableBinder.VisitParameter(ParameterExpression node)
   at System.Linq.Expressions.ParameterExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.Compiler.VariableBinder.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitMethodCall(MethodCallExpression node)
   at System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.Compiler.VariableBinder.Visit(Expression node)
   at System.Dynamic.Utils.ExpressionVisitorUtils.VisitArguments(ExpressionVisitor visitor, IArgumentProvider nodes)
   at System.Linq.Expressions.ExpressionVisitor.VisitMethodCall(MethodCallExpression node)
   at System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.Compiler.VariableBinder.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitBinary(BinaryExpression node)
   at System.Linq.Expressions.BinaryExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.Compiler.VariableBinder.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.Visit(ReadOnlyCollection`1 nodes)
   at System.Linq.Expressions.Compiler.VariableBinder.VisitBlock(BlockExpression node)
   at System.Linq.Expressions.BlockExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.Compiler.VariableBinder.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitMemberBinding(MemberBinding node)
   at System.Linq.Expressions.ExpressionVisitor.Visit[T](ReadOnlyCollection`1 nodes, Func`2 elementVisitor)
   at System.Linq.Expressions.ExpressionVisitor.VisitMemberInit(MemberInitExpression node)
   at System.Linq.Expressions.MemberInitExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.Compiler.VariableBinder.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.Visit(ReadOnlyCollection`1 nodes)
   at System.Linq.Expressions.Compiler.VariableBinder.VisitLambda[T](Expression`1 node)
   at System.Linq.Expressions.Expression`1.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.Compiler.VariableBinder.Visit(Expression node)
   at System.Linq.Expressions.Compiler.LambdaCompiler.Compile(LambdaExpression lambda)
   at System.Linq.Expressions.LambdaExpression.Compile()
   at Microsoft.EntityFrameworkCore.Cosmos.Query.Internal.CosmosShapedQueryCompilingExpressionVisitor.VisitShapedQuery(ShapedQueryExpression shapedQueryExpression)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at System.Linq.Expressions.Expression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   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 System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Program.<Main>$(String[] args) in CosmosBug\Program.cs:line 8

[ajcvickers]

@devbrsa Please test using EF Core 8 RC 1 and report back if you are still seeing an issue.

[devbrsa]

@devbrsa Please test using EF Core 8 RC 1 and report back if you are still seeing an issue.

@ajcvickers The error persists in the given version provided (EF Core 8 RC 1 (rc.1.23419.6)).

System.NullReferenceException: Object reference not set to an instance of an object.
   at lambda_method6(Closure, QueryContext, JObject)
   at Microsoft.EntityFrameworkCore.Cosmos.Query.Internal.CosmosShapedQueryCompilingExpressionVisitor.QueryingEnumerable`1.Enumerator.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Program.<Main>$(String[] args)

[maumar]

this seems to fixed now @ajcvickers