LINQ：寻找想法

Question

我从 LINQ 开始，这是我的代码片段。

var filterList = new List<string>()
            {
                "ACRating",
                "Axles",
                "SafetyCodes",
                "BuiltInFeatures"
            }

foreach( var i in filterList )
{
  var filter = i;
  var xList = Vehicles.FilterSpecList( filter );

  foreach ( var j in xList )
  {
    if ( xList.Count() == 1 ) /*Will Not Work since a list could have a single value.*/
    {
      switch( j.FeatureName )
      {                 
        case "ACRating":
          v.AcRating = j.Value;
          Console.WriteLine( j );
          break;
       }
    }
    else
    {
      switch( j.FeatureName )
      {
        //Am trying to still figure out how to get all the items in BuiltInFeatures, but you get the idea.
        case "BuiltInFeatures"
        {
          v.BuiltInFeatures = "MP3" + "SUNROOF";
          break;
        }
      }
    }
  }
}

我面临的问题是 xList.Count 不是查看列表值的可靠方法。有没有某种方法可以让我以某种方式将过滤器列表中的项目标记为列表而不是单个值。所以当我在代码中进行比较时，我不必依赖xList.Count。

Answer 1

这是我在 LinqPad 中创建的示例应用程序：
M 是您的 xList 的类型。如果您需要更多东西，您可以扩展它。
我确信有比这更流畅的解决方案，但我对你的项目不太了解，这是我能做的最好的......:)

class M
{
    public String FeatureName;
    public IEnumerable<String> Value;
}

M FilterSpecList(String filterName)
{
    if (filterName == "ACRating")
        return new M {FeatureName = "ACRating", Value = new [] {"OK",}};
    else if (filterName == "BuiltInFeatures")
        return new M {FeatureName = "BuiltInFeatures", Value = new[] {"MP3", "Sunroof",}};
    else
        return new M();//throw new Exception("More..");
}

void Main()
{
    List<String> filterList = new List<String>()
    {
        "ACRating",
        "Axles",
        "SafetyCodes",
        "BuiltInFeatures",
    };

    foreach (String filter in filterList)
    {
        var xList = FilterSpecList(filter);

        switch (xList.FeatureName)
        {
            case "ACRating":
                Console.WriteLine(xList.Value.Single());
                break;
            case "BuiltInFeatures":
                Console.WriteLine(String.Join(" + ", xList.Value));
                break;
            default:
                break;
        }
    }

}

Answer 2

我想我有一个可能的答案。
这就是我心中的改变。我回答而不是评论的原因是评论空间不足。

我希望我已经正确地闭合了所有牙套。

var filterList = new Dictionary<string, string>
                               {
                                    {"ACRating", "Property"},
                                    {"Axles", "Property"}
                                    {"SafetyCodes","List"}
                                    {"BuiltInFeatures","List"}
                               };   

                foreach(KeyValuePair<string,string> i in filterList)
                {
                    var filter = i.Key;
                    var xList = Vehicles.FilterSpecList(filter);
                    if (i.Value == "List")
                    {
                        foreach (var j in xList)
                        {
                            switch(j.FeatureName)
                            {
                            case "BuiltInFeatures"
                            {
                                    v.BuiltInFeatures = "x," + "y";
                                    break;
                            }
                    }
                    else if(i.Value == "Property")
                    {
                foreach (var j in xList)
                        {
                        switch(j.FeatureName)
                            {                   
                                case "ACRating":
                                    v.AcRating = j.Value;
                                    Console.WriteLine(j.ToString());
                                    break;
                            }
                    }

欢迎改进。

Answer 3

我仍在试图弄清楚列表中发生了什么。然而乍一看，您似乎可以使用

.ToLookUp()' “nofollow”>msdn

ToLookup(IEnumerable,
Func) 方法返回一个
查找，一对多
将键映射到的字典
值的集合。查找不同于
字典，其中
执行键的一对一映射
为单个值。

默认的相等比较器默认
用于比较键。