根据id </t>在List <t>中查找项目

Question

我要做的是在我的对象中获取一个List<Feature>，其中包含一系列功能。

我有两个主要类，用于保存有关项目的信息：

public class Feature
{
    public int FeaturePackId { get; set; }
    public string FeatureDescription { get; set; }
    public int FeatureId { get; set; }
    public bool AlwaysOn { get; set; }
}

public class FeaturePack
{
    public int FeaturePackId { get; set; }
    public List<Feature> Features { get; set; }
}

FeaturePack包中有ID和功能列表。

下面我将从GetPSTNFeaturePacksById()获取Feautres列表然后迭代此列表并根据其ID将这些项目放入单独的列表中。从这里我有两个清单。 SelectFeature列表包含IDs大于0的功能列表。如何将这些功能添加到FeaturePack FeaturePackID Feature内的ID对象中等于FeaturePack

的Features = CommonMethods.GetPSTNFeaturePacksById(); foreach (var item in Features) { if (item.FeaturePackId == 0) { DefaultFeatures.Add(new Feature { FeaturePackId = item.FeaturePackId, FeatureDescription = item.FeatureDescription, FeatureId = item.FeatureId, AlwaysOn = item.AlwaysOn }); } else { SelectFeatures.Add(new Feature { FeaturePackId = item.FeaturePackId, FeatureDescription = item.FeatureDescription, FeatureId = item.FeatureId, AlwaysOn = item.AlwaysOn }); } }

List<FeaturePack>

简而言之，我希望List<Feature>包含FeaturePacks: FeaturePackId 1 Features FeaturePackId = 1 FeaturePackDescription = "lorum ipsum" FeatureId = 1 AlwaysOn = True / FeaturePackId = 1 FeaturePackDescription = "lorum ipsum" FeatureId = 1 AlwaysOn = True FeaturePackId 2 Features FeaturePackId = 2 FeaturePackDescription = "lorum ipsum" FeatureId = 3 AlwaysOn = True / FeaturePackId = 2 FeaturePackDescription = "lorum ipsum" FeatureId = 4 AlwaysOn = True ...

如何生成与此类似的输出？

var distinctGroups = (from z in SelectFeatures
                            orderby z.FeaturePackId
                            select z.FeaturePackId).Distinct();

        foreach (var gp in distinctGroups)
        {
            foreach (var item in SelectFeatures)
            {
                if (item.FeaturePackId == gp)
                {
                    FeaturePack.Add(new FeaturePack
                    {
                        FeaturePackId = gp,
                        Features = item.AsList()
                    });
                }
            }
        }

修改

新尝试：

{{1}}

这是每个功能的FeaturePack的输出，我如何修改它以使相关功能在同一个包中？

Answer 1

您需要一个简单的GroupBy：

Features.GroupBy(f => f.FeaturePackId)
        .Select(g => new FeaturePack{ FeaturePackId = g.Key,
                                      Features = g.ToList() })
        .ToList();

---

逐一打破这个：

Features.GroupBy(f => f.FeaturePackId)

收集Feature个列表并将其分组到IEnumerable<IGrouping<Key, Value>>，其中Key是我们提供的函数的结果，在本例中为f => f.FeaturePackId，并且Value是我们正在使用的对象列表（在本例中为Feature s）。在此声明之后，我们将Feature的所有FeaturePackId与一组中的FeaturePackId放在一起，其中包含多个这些组（每 .Select(g => new FeaturePack{ FeaturePackId = g.Key, Features = g.ToList() }) .ToList(); 一个）。

Feature

然后，此选择将​​获取每组FeaturePack并从中创建f => f.FeaturePackId。组的关键是上面的函数Feature的结果，组本身就是Select的列表。此IEnumerable<FeaturePack>的结果是FeaturePack，其中每个Features都填充了ToList()列表。对IEnumerable<FeaturePack>的最终通话会将List<FeaturePack>转换为{{1}}。

Answer 2

你应该这样做：

from z in SelectFeatures
order z by z.FeaturePackId into g
select new FeaturePack { 
                        FeaturePackId = g.Key, 
                        Features = g}

public class FeaturePack
{
    public int FeaturePackId { get; set; }
    public IEnumerable<Feature> Features { get; set; }
}

Answer 3

开始学习LINQ，但它可以帮助你，但它是匿名类型：

var SelectedFeatures_lookup = SelectedFeatures.ToLookUp(p=>p.FeaturePackId);
var query =     from feature in SelectedFeatures
                group feature by feature.FeaturePackId into g
                select new
                {
                    FeaturePackId = g.Key,
                    Features = g
                };

foreach(var q in query)
{
       Console.WriteLine("FeaturePack = " + q.FeaturePackId);
       Console.WriteLine("Features: ");
       (foreach var qq in q.Features)
       {
            Console.WriteLine("\t " + qq.FeaturePackId);
            Console.WriteLine("\t " + ...);
       }
}

如果不起作用，请尝试给我答案

Answer 4

这应该适合你：

var SelectFeatures = Features.Where(item => item.FeaturePackId != 0)
                .GroupBy(item => item.FeaturePackId)
                .Select(grp => new FeaturePack { FeaturePackId = grp.Key, Features = grp.ToList() })
                .ToList();
var DefaultFeatures = Features.Where(item => item.FeaturePackId == 0).ToList();