在列表中查找项目<基于id

本文关键字：基于 id 项目 查找 列表 | 更新日期: 2023-09-27 18:14:36

我要做的是将List<Feature>放入我的对象中，该对象包含功能列表。

我有两个主要的类保存关于项目的信息:

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; }
}

一个FeaturePack有一个ID和一个功能列表。

下面我得到了GetPSTNFeaturePacksById()的功能列表，然后我遍历该列表，并根据它们的ID将项目放入单独的列表中。从这里我有两个列表。SelectFeature列表包含IDs大于0的特征列表。我如何将这些添加到FeaturePack对象中，其中Feature中的FeaturePackID等于FeaturePack的ID 

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
       });
    }
}

总之，我想要一个包含List<Feature>的List<FeaturePack>

我怎样才能产生类似的输出?

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
    ...

编辑

新尝试:

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()
                    });
                }
            }
        }

这个的输出是每个特性的一个FeaturePack，我如何修改它，使相关的特性在同一个包中?

在列表中查找项目<基于id

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();

逐条分解:

Features.GroupBy(f => f.FeaturePackId)

获取Feature s列表并将它们分组为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, Value是我们正在处理的对象的列表(在本例中为Feature)。在此语句之后，我们将所有Feature s与相同的FeaturePackId一起放在一个组中，其中有几个组(每个FeaturePackId一个)。

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

这个select然后获取每组Feature并从中创建一个FeaturePack。组的键是上面的函数f => f.FeaturePackId的结果，而组本身是我们的Feature列表。Select的结果是IEnumerable<FeaturePack>，其中每个FeaturePack都填充了它的Features列表。最后对ToList()的调用将IEnumerable<FeaturePack>转换为List<FeaturePack>。

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; }
}

我开始学习LINQ，但它可能会帮助你，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 " + ...);
       }
}

请试着给我答案，如果不工作

这应该可以为您工作:

<>之前var SelectFeatures =功能。其中(item => item。= 0).GroupBy(item => item. featurepackid).选择(grp => new FeaturePack {FeaturePackId = grp;Key, Features = grp.ToList()}).ToList ();var DefaultFeatures =功能。其中(item => item。FeaturePackId == 0).ToList();
相关文章：