c# - 基于 Linq 构建复杂的搜索过滤器

Question

想知道是否有针对这种复杂情况的 linq 解决方案；例如，客户选择颜色:红色、尺寸:大号、类型:棉。如果我确定客户每次都会选择这些过滤器，我会这样做:

var shirts = ListOfShirts.Where(i=> i.Color.Contains("red") && Size.Contains("Large") && Type.Contains("Cotton"));

这是当前结构和一个从 View 中接受多个过滤器的操作方法:

类:

public partial class Shirt {
   public long ID { get; set; }
   public string Color  { get; set; }
   public string Size { get; set; }
   public string Type { get; set; }
}

public class SelectedFilter {
   public string Name { get; set; } // Filter Menu Title
   public string Value { get; set; }
}

Controller :

public ActionResult Filter(IList<SelectedFilter> selectedFilters) {
       var model = new List<Shirt>();
       Shirt ListOfShirts = db.GetAllShirts();
       var groups = selectedFilters.GroupBy(i => i.Name);

            foreach (var g in groups)
            {
                var GroupName = g.FirstOrDefault().name;
                var GroupValues = g.Select(i => i.value).ToList();

                if (g.FirstOrDefault().name == "Color")
                {
                    model = ListOfShirts.Where(i => GroupValues.Contains(i.Color)).ToList();
                }
                else if (g.FirstOrDefault().name == "Size")
                {
                    model = ListOfShirts.Where(i => GroupValues.Contains(i.Size)).ToList();
                }
                else if (g.FirstOrDefault().name == "Type")
                {
                    model = ListOfShirts.Where(i => GroupValues.Contains(i.Type)).ToList();
                }
            }
   }

Answer 1

一种(粗暴的)方法:

public ActionResult Filter(IList<SelectedFilter> selectedFilters) {
       var model = new List<Shirt>();
       IEnumerable<Shirt> ListOfShirts = db.GetAllShirts();

        IEnumerable<Shirt> filteredListOfShirts = ListOfShirts
           .Where(shirt => {
               return (
                    (selectedFilters.Any(filter => filter.Name == "Color" && !string.IsNullOrWhiteSpace(filter.Value)) ? // is Color filter set?
                        selectedFilters.Any(filter =>
                        {
                            return (filter.Name == "Color" && shirt.Color == filter.Value);
                            }) : true)
                    &&
                    (selectedFilters.Any(filter => filter.Name == "Size" && !string.IsNullOrWhiteSpace(filter.Value)) ? // is Size filter set?
                        selectedFilters.Any(filter =>
                       {
                           return (filter.Name == "Size" && shirt.Size == filter.Value);
                       }) : true)
                    &&
                    (selectedFilters.Any(filter => filter.Name == "Type" && !string.IsNullOrWhiteSpace(filter.Value)) ? // is Type filter set?
                        selectedFilters.Any(filter =>
                        {
                            return (filter.Name == "Type" && shirt.Type == filter.Value);
                        }) : true)
                    );
               });

        model = filteredListOfShirts.ToList();

   }

如果您有多个具有相同名称的过滤器值，这也应该有效

{Name="Color",Value="Red"},{Name="Color",Value="Blue"}