EF Core First Eager Loading Inheritance Filter

Question

I have the following entities defined:

public class Computer
{
    [Key]
    public int Id { get; set; }

    [Required]
    [StringLength(15)]
    public string Name { get; set; } = null!;

    [Required]
    public List<ComputerAction> Actions { get; set; } = new();
}

public abstract class ComputerAction
{
    [Key]
    public int Id { get; set; }

    public List<HistoryEntry> History { get; set; } = new();

    public Computer Computer { get; set; } = null!;

    [NotMapped]
    public Status Status => History.LastOrDefault()?.Status ?? Status.Unknown;

    public abstract Task<HistoryEntry> ExecuteAsync();
}

public class RenewCertificateAction : ComputerAction
{
    public override Task<HistoryEntry> ExecuteAsync() 
    {
        // Whatever
    }
}

public class PingAction : ComputerAction
{
    private readonly Ping _ping = new();

    public override async Task<HistoryEntry> ExecuteAsync()
    {
        // Whatever
    }
}

public class HistoryEntry
{
    [Key]
    public int Id { get; set; }

    [Required]
    public Status Status { get; set; }

    [Required]
    public DateTime WhenExecuted { get; set; }
}

And my DbContext as follows:

public class ComputerContext : DbContext
{
    public ComputerContext(DbContextOptions<ComputerContext> options)
        : base(options)
    {
    }

    public static readonly string ComputerDb = nameof(ComputerDb);

    public DbSet<Computer> Computers { get; set; } = null!;

    public DbSet<RenewCertificateAction> RenewCertificateActions { get; set; } = null!;

    public DbSet<PingAction> PingActions { get; set; } = null!;

    public DbSet<HistoryEntry> History { get; set; } = null!;

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Computer>().HasMany(x => x.Actions).WithOne(x => x.Computer).OnDelete(DeleteBehavior.Cascade);
        modelBuilder.Entity<ComputerAction>().ToTable("ComputerActions").HasMany(x => x.History).WithOne().OnDelete(DeleteBehavior.Cascade);
        modelBuilder.Entity<HistoryEntry>().ToTable("ComputerActionEntries");
    }
}

I'd like to get a list of all computers, but if they happen to have an action of type PingAction , then also load that action (and only that action, not all actions).

What is logical to me is something like dbContext.Computers.Include(x => x.Actions.OfType<PingAction>()) but that apparently can't be translated into a query. How can I do an Include only of Actions of a particular type?

Answer 1

you can use where inside include:

dbContext.Computers.Include(x => x.Actions.Where(action => action is PingAction))

more explanation: : https://stackoverflow.com/a/61147681/11143288