Entity Framework Core 6 Tracking Behavior Issue with Detached Entities in a Complex Object Graph
I'm refactoring my project and I'm prototyping a solution and I'm facing a problem with Entity Framework Core 6 when trying to update a complex object graph containing detached entities... Specifically, I have a parent entity that includes several child entities, some of which are already tracked by the context, while others are not. When I attempt to update the parent entity with the detached child entities, I get the following error: `InvalidOperationException: The instance of entity type 'ChildEntity' cannot be tracked because another instance with the same key value for {'Id'} is already being tracked.` Here’s a simplified version of my model: ```csharp public class ParentEntity { public int Id { get; set; } public List<ChildEntity> Children { get; set; } } public class ChildEntity { public int Id { get; set; } public string Name { get; set; } } ``` In my service method, I’m trying to handle updates as follows: ```csharp public async Task UpdateParentAsync(ParentEntity updatedParent) { using (var context = new MyDbContext()) { var existingParent = await context.Parents.Include(p => p.Children) .SingleOrDefaultAsync(p => p.Id == updatedParent.Id); if (existingParent != null) { existingParent.Children.Clear(); existingParent.Children.AddRange(updatedParent.Children); context.Update(existingParent); await context.SaveChangesAsync(); } } } ``` I’ve tried using `context.Entry(existingParent).State = EntityState.Modified;` but it doesn’t resolve the tracking issue. I also considered using `AsNoTracking()` when querying the existing parent, but I need to update the existing relationships. What am I missing here? How can I properly manage entity states in this scenario to avoid the tracking error? Hoping someone can shed some light on this.