Query Filter: Inconsistent number of records returned with .ToList()/.Count() #36360
Description
Bug description
There appears to be an issue with resolving queries in the case that a query filter .HasQueryFilter() has been used. In the provided example calling .ToList() on query returns 1 record, and the .Count() returns 2 records.
I believe this is due to the foreign key being required and thus resolving to some kind of inner join that always expects a result. However the query filter means that an inner join is inappropriate.
I first came across this issue with SQL Server, and then produced a simple reproducible version in the attached code using the In Memory Database provider. I have tested this against version 9.0.7 of the packages.
In my real world use case I use these to drive a datagrid. Which I believe is fairly common. I would have also expected possibly rewriting the ParentName assignment might result in a different output:
ParentName = x.Parent != null ? x.Parent.Name : null
but it did not. I personally believe in my example the .ToList() should return both records, but the bigger issue is the inconsistency.
Your code
public class MyDbContext : DbContext
{
public DbSet<Child> Children { get; set; }
public DbSet<Parent> Parents { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseInMemoryDatabase("MyDatabase");
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Parent>().HasQueryFilter(x => !x.Deleted);
modelBuilder.Entity<Child>().HasQueryFilter(x => !x.Deleted);
base.OnModelCreating(modelBuilder);
}
}
public class Child
{
public int Id { get; set; }
public string Name { get; set; }
public int ParentId { get; set; }
public Parent Parent { get; set; }
public bool Deleted { get; set; }
}
public class Parent
{
public int Id { get; set; }
public string Name { get; set; }
public bool Deleted { get; set; }
}
using var context = new MyDbContext();
// Add a new customer
context.Parents.Add(new Parent { Name = "Parent1" });
context.Parents.Add(new Parent { Name = "Parent2" });
context.SaveChanges();
context.Children.Add(new Child { Name = "Child1", ParentId = 1 });
context.Children.Add(new Child { Name = "Child2", ParentId = 2 });
context.SaveChanges();
var parent1 = context.Parents.Where(x => x.Id == 1).FirstOrDefault();
parent1.Deleted = true;
context.SaveChanges();
var query = context.Children.Select(x => new
{
ChildName = x.Name,
ParentName = x.Parent.Name
});
var data = query.ToList();
var count = query.Count();
Console.WriteLine($"Data: {data.Count} Count: {count}");
// OUTPUT: data.Count == 1
// OUTPUT: count == 2
// Note they are not the same(!)Stack traces
Verbose output
EF Core version
9.0.7
Database provider
SqlServer and InMemoryProvider
Target framework
.NET 9.0
Operating system
Windows 11
IDE
Visual Studio 17.4