Cosmos db complex properties can be configured but are not working. #37297
Description
Bug description
Complex properties in cosmos db can be configured, but are not stored in the db, nor are they retrieved or can be queried.
Originally: #31253 was named: Add Cosmos support for complex types, but was renamed to: Add Cosmos support for complex type collections
Complex collections throw when configured in Cosmos db, but complex properties do not.
I'd say this is a bug as they can be configured, but don't work. However a solution could be to just implement complex properties.
Your code
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Diagnostics;
using var context = new Context(
new DbContextOptionsBuilder()
.UseCosmos("AccountEndpoint=https://localhost:8081/;AccountKey=C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==", "Testing")
.Options);
await context.Database.EnsureDeletedAsync();
await context.Database.EnsureCreatedAsync();
context.Add(new Entity
{
ComplexType = new ComplexType
{
Name = "Test"
},
});
await context.SaveChangesAsync();
context.ChangeTracker.Clear();
var entity = await context.Set<Entity>().ToListAsync();
Console.WriteLine(entity[0].ComplexType.Name == "Test"); // False
public class Context : DbContext
{
public Context(DbContextOptions options) : base(options)
{
}
protected Context()
{
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Entity>(entity =>
{
entity.ComplexProperty(x => x.ComplexType);
});
}
}
public class Entity
{
public Guid Id { get; set; } = Guid.NewGuid();
public ComplexType ComplexType { get; set; }
}
public class ComplexType
{
public int Id { get; set; }
public string Name { get; set; }
}EF Core version
10.0.0 and main branch (11.0.0)
Database provider
Microsoft.EntityFrameworkCore.Cosmos
Target framework
.NET 10
Operating system
Windows 11
IDE
VS 2026