Unable to apply Take() to a navigation property

[mcchessers-sp]

Unable to apply Take() to a navigation property

[fiseni]

Yes, you might open an issue there (if there isn't one already).

[ardalis]

The first thing to check is if you can make the query work directly with your dBcontext. Apply your LINQ to dBContext.Players and see if you can get it to work. If not, the problem isn't related to this Specification package.

[fiseni]

Hi @mcchessers-sp,

Unfortunately, it has nothing to do with this library. We're passing the expression as it is. I suspect the MySQL provider doesn't know how to translate the filtered include which contains Take.

You may try to test without specifications, working directly with DbContext.

[fiseni]

Here I created a full test app using SqlServer provider. It works as expected. Try the same code with MySql provider.

using Ardalis.Specification;
using Ardalis.Specification.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;

await AppDbContext.SeedAsync();

using var dbContext = new AppDbContext();
var repo = new Repository<Customer>(dbContext);
var spec = new CustomerSpec();

var customer = await repo.FirstOrDefaultAsync(spec);

Console.WriteLine($"We fetched {customer!.Addresses.Count} addresses!");

public class CustomerSpec : Specification<Customer>
{
    public CustomerSpec()
    {
        Query.Include(x => x.Addresses.Take(2));
    }
}
public interface IRepository<T> : IRepositoryBase<T> where T : class
{
}
public class Repository<T> : RepositoryBase<T>, IRepository<T> where T : class
{
    public Repository(AppDbContext dbContext) : base(dbContext)
    {
    }
}
public record Address
{
    public int Id { get; set; }
    public int CustomerId { get; set; }
}
public record Customer
{
    public int Id { get; set; }
    public List<Address> Addresses { get; set; } = new();
}
public class AppDbContext : DbContext
{
    public DbSet<Customer> Customers => Set<Customer>();
    public DbSet<Address> Addresses => Set<Address>();
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        var connectionString = "Data Source=(localdb)\\MSSQLLocalDB;Initial Catalog=IncludeTest;Integrated Security=SSPI;ConnectRetryCount=0;";
        optionsBuilder.UseSqlServer(connectionString).LogTo(Console.WriteLine);
    }

    public static async Task SeedAsync()
    {
        using var dbContext = new AppDbContext();
        await dbContext.Database.EnsureDeletedAsync();
        await dbContext.Database.EnsureCreatedAsync();
        var customer = new Customer
        {
            Addresses = new List<Address>()
            {
                new Address(),
                new Address(),
                new Address()
            }
        };
        dbContext.Customers.AddRange(customer);
        await dbContext.SaveChangesAsync();
    }
}

[mcchessers-sp]

Thank you for the suggestions. I tried using DbContext outwith the specification:

DbContext.Players.Where(p => p.Id == (int)TestPlayers[0].Id).Include(p => p.ActiveDays.Take(1));

.. and got the same error, which would suggest that perhaps the driver (Pomelo) may be at fault?