static class ListReturnPagingObjectExtension
{
static public object Paging<T>(this IEnumerable <T> l, NameValueCollection form)
{
if(!(l is IQueryable<T>) && !(l is IList<T>))
l = l.ToList();
var ql = l.AsQueryable();
try
{
var input = new
{
Skip = int.Parse(form["start"]),
Count = int.Parse(form["limit"]),
OrderBy = new Func<IQueryable<T>, IQueryable<T>>(q =>
{
var sort = form["sort"];
var dir = form["dir"] ?? "ASC";
if(string.IsNullOrEmpty(sort) || (dir != "ASC" && dir != "DESC"))
return q;
var paramExpr = Expression.Parameter(typeof(T), "item");
var ksExpr = Expression.Lambda(Expression.Property(paramExpr, sort), paramExpr);
var types = new [] { ql.ElementType, ksExpr.Body.Type };
var mce = Expression.Call(typeof(Queryable), dir == "ASC" ?
"OrderBy" : "OrderByDescending", types, ql.Expression, ksExpr);
return (IQueryable<T>) ql.Provider.CreateQuery(mce);
})
};
var output = new
{
Data = input.OrderBy(ql).Skip(input.Skip).Take(input.Count),
Count = ql.Count(),
};
return output;
}
catch
{
if (form["start"] != null && form["limit"] != null)
{
var skip = int.Parse(form["start"]);
var count = int.Parse(form["limit"]);
var output = new
{
Data = l.ToList().Skip(skip).Take(count),
Count = l.Count()
};
return output;
}
else
{
return l.ToList();
}
}
}
}
