OData $orderby on complex property in projected DTO causes error

[aakashbashyal-maitri]

I'm building an OData endpoint using EF Core and ODataQueryOptions, and I want to allow clients to $orderby a property that comes from a nested collection in my projection.

I have the following entities and DTOs:

public class Customer
{
    public int Id { get; set; }
    public string FullName { get; set; }
    public DateTime DateOfBirth { get; set; }
    public ICollection<CustomerRating> CustomerRatings { get; set; }
}

public class CustomerRating
{
    public DateTime CreatedAt { get; set; }
    public RatingType RatingType { get; set; }
}

public class CustomerSummaryDto
{
    public int Id { get; set; }
    public string FullName { get; set; }
    public DateTime DateOfBirth { get; set; }
    public CustomerRatingDto LatestRating { get; set; }
}

public class CustomerRatingDto
{
    public RatingType RatingType { get; set; }
}

public enum RatingType
{
    Low,
    Medium,
    High
}

My query looks like this:

var queryProjection = dbContext.Customers.Select(c => new CustomerSummaryDto
{
    Id = c.Id,
    FullName = c.FullName,
    DateOfBirth = c.DateOfBirth,
    LatestRating = c.CustomerRatings
        .OrderByDescending(r => r.CreatedAt)
        .Select(r => new CustomerRatingDto { RatingType = r.RatingType })
        .FirstOrDefault()
});

var finalQuery = (IQueryable<CustomerSummaryDto>)queryOptions.ApplyTo(queryProjection, new ODataQuerySettings());
var result = await finalQuery.ToListAsync();

I want to allow the client to do:

GET /odata/CustomerSummaryDtos?$orderby=LatestRating/RatingType desc

But I get the following error:

{
  "type": "https://tools.ietf.org/html/rfc9110#section-15.6.1",
  "title": "An error occurred while processing your request.",
  "status": 500,
  "detail": "Cannot apply ODataQueryOptions of 'MyApp.Dto.CustomerSummaryDto' to IQueryable of 'MyApp.Models.Customer'. (Parameter 'query')"
}

How can I enable $orderby on a nested/complex property in a DTO projected from an EF Core query using OData?