Count() returns 1 result when there is no record in Results view-CodePudding

 var user = await context.Customers
                .Include(x => x.CustomerPreferences)
                .ThenInclude(up => up.CustomerNations)
                .Where(x => x.Id == userId).FirstOrDefaultAsync(cancellationToken);

CustomerNations Entity has

public Customer Customer { get; set; } = null!;
public virtual IList<CustomerNation> CustomerNations { get; set; } = new List<CustomerNation>();

I have no record in CustomerNation table. However, according to this code, there is one record in CustomerNations. When I observe it during debug, Result view shows 0 results.

var preferences= user.preferences
                .ToList();

if (preferences.Any())
{
    var customerNations= user.CustomerPreferences
        .Select(x => x.CustomerNations);

    if (customerNations.Count() != 0) //Both, Any() and Count shows there is one record. I check dropdown and Result view has 0 results.
    {
        foreach (var nation in customerNations)
        {
            context.Remove(counterParty);
        }
    }
}

Count is 1 but result view says diffent

CodePudding user response：

Enumerable.Select<TSource,TResult> returns an IEnumerable<TResult>. In this case, since CustomerPreferences.CustomerNations is of type IList<CustomerNation>, user.CustomerPreferences.Select(x => x.CustomerNations) is returning an IEnumerable<IList<CustomerNation>>. So, your customerNations probably has one item which itself is an empty IList<CustomerNation>.

If you want to flatten all of the CustomerNation instances into a IEnumerable<CustomerNation> you should use Enumerable.SelectMany.

var customerNations = user.CustomerPreferences.SelectMany(x => x.CustomerNations)