Question

I want the following two queries to be executed in single round trip to database so I’m using ToFutureValue.

var query = AsQueryable()
    .Where(x => x.User == user);

var singinCount = query
    .Where(x => x.ActionDate >= from && x.ActionDate <= to)
    .ToFutureValue(q => q.Count());

var lastSignin = query
    .Where(x => x.ActionName.ToLower() == Actions.Signin))
    .ToFutureValue(q => q.Max(x => x.ActionDate));

The problem is that Count and Max returns result but not IQueryable. I have found the following extension that enables me to pass Count to ToFutureValue:

public static IFutureValue<TResult> ToFutureValue<TSource, TResult>(
    this IQueryable<TSource> source, Expression<Func<IQueryable<TSource>, TResult>> selector)
        where TResult : struct
    {
        var provider = (INhQueryProvider)source.Provider;
        var method = ((MethodCallExpression)selector.Body).Method;
        var expression = Expression.Call((Expression)null, method, source.Expression);

        return (IFutureValue<TResult>)provider.ExecuteFuture(expression);
    }

Now I need to adopt that extension for Max because I have to pass arguments to Max (.ToFutureValue(q => q.Max(x => x.ActionDate))). How can I do that?

Answer 1

as a workaround

var lastSignin = query
    .Where(x => x.ActionName.ToLower() == Actions.Signin))
    .OrderByDescending(x => x.ActionDate)
    .Take(1)
    .ToFutureValue();