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我在概念化使用 LINQ 应该相当简单的东西时遇到了麻烦。我有一个要根据子对象的 id 值缩小或过滤的集合。

我的主要收藏包括一个景点列表。这是一个点的样子：

public class Spot
{
    public virtual int? ID { get; set; }
    public virtual string Name { get; set; }
    public virtual string Description { get; set; }
    public virtual string TheGood { get; set; }
    public virtual string TheBad { get; set; }
    public virtual IEnumerable<Season> Seasons { get; set; }
    public virtual IEnumerable<PhotographyType> PhotographyTypes { get; set; }
}

我正在尝试按 PhotographyType 和 Season 过滤 Spots 列表。我有一个 PhotographyTypes 和 Seasons 的 id 列表，每个都在一个 int[] 数组中。这些列表如下所示：

criteria.PhotographyTypeIds //an int[]
criteria.SeasonIds //an int[]

我想构建一个仅包含具有与上述列表中的子对象 (id) 匹配的 Spot 的集合。此功能的目标是按类型和季节过滤一组摄影点，并仅显示匹配的点。任何建议将不胜感激。

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3 回答 3

1

谢谢大家的建议。我最终解决了这个问题。我确定这不是最好的方法，但它现在正在工作。因为这是一个搜索过滤器，所以有很多条件。

private List<Spot> FilterSpots(List<Spot> spots, SearchCriteriaModel criteria)
    {
        if (criteria.PhotographyTypeIds != null || criteria.SeasonIds != null)
        {
            List<Spot> filteredSpots = new List<Spot>();

            if (criteria.PhotographyTypeIds != null)
            {
                foreach (int id in criteria.PhotographyTypeIds)
                {
                    var matchingSpots = spots.Where(x => x.PhotographyTypes.Any(p => p.ID == id));
                    filteredSpots.AddRange(matchingSpots.ToList());
                }
            }

            if (criteria.SeasonIds != null)
            {
                foreach (int id in criteria.SeasonIds)
                {
                    if (filteredSpots.Count() > 0)
                    {
                        filteredSpots = filteredSpots.Where(x => x.Seasons.Any(p => p.ID == id)).ToList();
                    }
                    else
                    {
                        var matchingSpots = spots.Where(x => x.Seasons.Any(p => p.ID == id));
                        filteredSpots.AddRange(matchingSpots.ToList());
                    }
                }
            }
            return filteredSpots;
        }
        else
        {
            return spots;
        }
    }
于 2013-04-14T21:50:42.673 回答
0

You have an array of IDs that has a Contains extension method that will return true when the ID is in the list. Combined with LINQ Where you'll get:

List<Spot> spots;   // List of spots
int[] seasonIDs;    // List of season IDs

var seasonSpots = from s in spots
                  where s.ID != null
                  where seasonIDs.Contains((int)s.ID)
                  select s;

You can then convert the returned IEnumerable<Spot> into a list if you want:

var seasonSpotsList = seasonSpots.ToList();
于 2013-04-14T07:26:17.137 回答
0

这可能会帮助您：

List<Spot> spots = new List<Spot>();
Spot s1 = new Spot();
s1.Seasons = new List<Season>() 
             { new Season() { ID = 1 }, 
               new Season() { ID = 2 }, 
               new Season() { ID = 3 } 
             };
s1.PhotographyTypes = new List<PhotographyType>() 
             { new PhotographyType() { ID = 1 }, 
               new PhotographyType() { ID = 2 } 
             };

Spot s2 = new Spot();
s2.Seasons = new List<Season>() 
             { new Season() { ID = 3 }, 
               new Season() { ID = 4 }, 
               new Season() { ID = 5 } 
             };
s2.PhotographyTypes = new List<PhotographyType>() 
             { new PhotographyType() { ID = 2 }, 
               new PhotographyType() { ID = 3 } 
             };

List<int> PhotographyTypeIds = new List<int>() { 1, 2};
List<int> SeasonIds = new List<int>() { 1, 2, 3, 4 };

spots.Add(s1);
spots.Add(s2);

然后：

var result = spots
             .Where(input => input.Seasons.All
                           (i => SeasonIds.Contains(i.ID)) 
                    && input.PhotographyTypes.All
                           (j =>  PhotographyTypeIds.Contains(j.ID))
                    ).ToList();
// it will return 1 value

假设：

public class Season
{
    public int ID { get; set; }
    //some codes
}
public class PhotographyType
{
    public int ID { get; set; }
    //some codes
}
于 2013-04-14T06:00:29.650 回答