public static IQueryable <T> Filter <T>(IQueryable <T> items, FilterAndSortingOptions options)
{
if (options != null)
{
List <FilterMetaRecord> filtersForCurrentType = list.GetFiltersForCurrentType(items.ElementType);
foreach (var f in options.Filters)
{
if (f.Value != null && f.Value.Count > 0)
{
var now_meta = filtersForCurrentType.FirstOrDefault(j => j.Name == f.Field);
if (now_meta != null)
{
if (!(now_meta.ParametrType != typeof(string) && (f.Value[0] == null || f.Value[0] == "")))
{
items = FilterByFilterMetaRecord(items, f, now_meta);
}
}
}
}
if (options.Sortings != null && options.Sortings.Count > 0)
{
var orderList = options.Sortings.Where(j => filtersForCurrentType.FirstOrDefault(i => i.Name == j.Field) != null).OrderBy(j => j.Priority).ToList();
if (orderList.Count > 0)
{
var orderedItems = SortingBySortingMetaRecord <T>(items, orderList[0], filtersForCurrentType.First(j => j.Name == orderList[0].Field));
for (int i = 1; i < orderList.Count; i++)
{
orderedItems = ThenSortingBySortingMetaRecord <T>(orderedItems, orderList[i], filtersForCurrentType.First(j => j.Name == orderList[i].Field));
}
items = orderedItems;
}
}
else
{
var defaultFilter = filtersForCurrentType.First(j => j.Name == "Default");
var defultSorting = new SortingRecord()
{
Direction = defaultFilter.DefaultSorting.ToString(), Field = "Default", Priority = 1
};
items = SortingBySortingMetaRecord <T>(items, defultSorting, defaultFilter);
}
}
return(items);
}
public static IOrderedQueryable <T> ThenSortingBySortingMetaRecord <T>(IOrderedQueryable <T> items, SortingRecord sort, FilterMetaRecord meta)
{
var param = Expression.Parameter(typeof(T), "x");
var propertyAccess = meta.Path.Split('.').Aggregate((Expression)param, Expression.Property);
if (sort.Direction == "asc")
{
return((IOrderedQueryable <T>)items.Provider.CreateQuery(Expression.Call(typeof(Queryable), "ThenBy", new Type[] { typeof(T), meta.ParametrType }, items.Expression, Expression.Lambda(propertyAccess, param))));
}
else
{
return((IOrderedQueryable <T>)items.Provider.CreateQuery(Expression.Call(typeof(Queryable), "ThenByDescending", new Type[] { typeof(T), meta.ParametrType }, items.Expression, Expression.Lambda(propertyAccess, param))));
}
}
