/// <summary>
/// Selects page from a collection.
/// </summary>
public static async Task <Page <TEntity> > ToPageAsync <TEntity>(this IQueryable <TEntity> query, PagingOptions options)
{
if (query == null)
{
throw new ArgumentNullException(nameof(query));
}
if (options == null)
{
throw new ArgumentNullException(nameof(options));
}
var result = query;
var skipCount = options.GetSkipCount();
if (skipCount > 0)
{
result = result.Skip(skipCount);
}
var takeCount = options.GetTakeCount();
var data = takeCount <= 0 ? new TEntity[0] : await result.Take(takeCount).ToArrayAsync();
var total = -1;
var overflow = false;
if (options.AcquireTotal)
{
if (options.MaximumCount != null)
{
var max = options.MaximumCount.Value * options.Size - options.Offset;
total = options.Offset + await query.Take(max + 1).CountAsync();
if (total > max)
{
overflow = true;
total = max;
}
}
else
{
total = options.Offset + await query.CountAsync();
}
}
return(new Page <TEntity>(
data,
options.Number,
options.Size,
total,
overflow
));
}
