LINQ select:要将集合传递到CONTAINS中

Question

该页面有6个下拉列表，用户可以选择单个项目或将列表保留在第一个项目上，即“任意”。那样的话，我想把所有的都还给你。例如，如果用户选择了土壤下坠.任何选择，沙，土和粘土。如果他们选择任何一个，我想从土壤表中选择所有的土壤类型。如何将土壤类型的集合传递到一个容器中？类似于：

*where soil.SOIL1.Contains("Sand", "Loam", "Clay")*

public List<PlantList> getMultiSelectPlantSearchResultBeSoMoLiHeZo(string Benefit, string Soil, string Moisture, string Light, string Height, string Zone)
{
    var plantList = from plant in db.PLANTs
                    join benefit in db.BENEFITs on plant.PLANT_ID equals benefit.PLANT_ID
                    join soil in db.SOILs on plant.PLANT_ID equals soil.PLANT_ID
                    join moisture in db.MOISTUREs on plant.PLANT_ID equals moisture.PLANT_ID
                    join light in db.LIGHTs on plant.PLANT_ID equals light.PLANT_ID
                    join height in db.HEIGHTs on plant.PLANT_ID equals height.PLANT_ID
                    join zone in db.ZONEs on plant.PLANT_ID equals zone.PLANT_ID
                    where plant.PLANT_ID == benefit.PLANT_ID
                    && benefit.BENEFIT1 == Benefit
                    && soil.SOIL1 == Soil
                    && moisture.MOISTURE1 == Moisture
                    && light.LIGHT1 == Light
                    && height.HEIGHT1 == Height
                    && zone.ZONE1 == Convert.ToInt16(Zone)
                    select new PlantList
                    {
                        plantId = plant.PLANT_ID,
                        plantName = plant.PL_NAME,
                        plantGenus = plant.PL_GENUS,
                        plantSpecies = plant.PL_SPECIES,
                        plantDesc = plant.PL_DESC,
                        plantImageThumb = plant.PL_IMAGE_THUMB,
                        plantBenefit = benefit.BENEFIT1,
                        plantSoil = soil.SOIL1,
                        plantMoisture = moisture.MOISTURE1,
                        plantLight = light.LIGHT1,
                        plantHeight = height.HEIGHT1,
                        plantZone = zone.ZONE1
                    };

    var DistinctItems = plantList.OrderBy(z => z.plantName).GroupBy(x => x.plantId).Select(y => y.FirstOrDefault()).ToList();
    return DistinctItems;

Answer 1

您可以使用IQueryable的可组合性

IQueryable<Soil> soils = db.SOILs;

if (soilTypes.Any())
{
    soils = soils.Where(s => soilTypes.Contains(s.Type));
}

var plantList = from plant in db.PLANTs
                join benefit in db.BENEFITs on plant.PLANT_ID equals benefit.PLANT_ID
                join soil in soils on plant.PLANT_ID equals soil.PLANT_ID
...

soilTypes包含用户选择的类型(一个或多个类型作为字符串列表)。如果用户选择“任意”，它应该是一个空列表(这实际上意味着选择标准被忽略)。因此，您应该根据用户在UI中选择的内容编写soilTypes。

这将被转换为一个SQL查询，soils是一个混合到plantlist查询中的表达式。

Answer 2

您可以在where子句上创建一个ContainsAny方法并调用它，参见下面的测试示例：

public static bool ContainsAny(string searchField, params string[] words) {
            foreach(string word in words) {
                if(searchField.Contains(word))
                    return true;
            }

            return false;
        }


        public static void Main(string[] args){
            var list = new List<string>() { "test", "test2", "Sand", "Loam", "Clay" };
            var selectedList = from item in list where ContainsAny(item, "Sand", "Loam", "Clay")
                               select item;
            foreach(var item in selectedList) {
                Console.WriteLine(item);
            }
            Console.ReadKey();
        }