c# - C# 中的字典词典

Question

我正在使用 C# 代码从 SQl SERVER 读取 SQL 表。

我的数据是这样的:

ZOO   Animal    Mn Tu
NDS     BAT     2   0
GOR     BAT     3   1
VTZ     BAT     1   2
MAS     BAT     0   0
CST     BAT     0   0
NDS     CAT     4   0
GOR     CAT     4   0
VTZ     CAT     2   0
MAS     CAT     7   0
CST     CAT     1   0
NDS     DOG     3   0
GOR     DOG     2   0
VTZ     DOG     1   0
MAS     DOG     3   0
CST     DOG     0   1
NDS     EGG     7   0
GOR     EGG     2   0
VTZ     EGG     0   0
MAS     EGG     0   0
CST     EGG     4   0

我写了一个 sql reader 命令，它运行了

sql = "SELECT * FROM table";

OleDbCommand cmd = new OleDbCommand(sql, conn);
        cmd.CommandTimeout = 600;
        using (OleDbDataReader reader = cmd.ExecuteReader())
        {


            while (reader.Read())
            {
                var location = reader.GetString(0).Trim();
                var animal= reader.GetString(1).Trim();
                var Monday= reader.GetValue(1).ToString().Trim();
                var Tuesday= reader.GetValue(3).ToString().Trim();

             }
        }

我创建了一个字典如下:

 private Dictionary<string, Dictionary<string, Dictionary<string, string>>> zooDict;
 zooDict= new Dictionary<string, Dictionary<string, Dictionary<string, string>>>();

理想情况下，我希望有这样的结构:

{
NDS:
    {
     BAT:
        {Mn: 2,
         Tu: 2},
     CAT:
        {
        MN: 4,
        Tu: 0
        }
     DOG:
        {
        MN: 3,
        Tu: 0
        }

     EGG:
        {
        MN: 7,
        Tu: 0
        }


    }
    GOR:
        .
        .
        .
        .
        .

}

我希望将此字典转换为 json 文件，但我无法将键和值添加到空字典中。我来自 python 背景，在那里我可以使用 defaultdict 创建字典字典而不会遇到关键错误。

任何创建字典的提示都将不胜感激。

---

if (!ZooDict.ContainsKey(location))
{
    var catDict = new Dictionary<string, string>();
    catDict.Add("Mon", Monday);
    catDict.Add("Tue", Tuesday);
    var AnimalDict = new Dictionary<string, Dictionary<string, string>>();
    AnimalDict.Add(animal, catDict);
    waitlistDict.Add(location, AnimalDict);
}
else
{
    if (!waitlistDict[location].ContainsKey(animal))
    {
        var catDict = new Dictionary<string, string>();
        catDict.Add("Mon", Monday);
        catDict.Add("Tue", Tuesday);
        var AnimalDict = new Dictionary<string, Dictionary<string, string>>();
        AnimalDict.Add(animal, catDict);
        waitlistDict[location] = AnimalDict;
    }
    else
    {
        if (waitlistDict[location][animal].ContainsKey("Mon"))
        {
            waitlistDict[location][animal]["Mon"] = Monday;
        }
        else
        {
            waitlistDict[location][animal]["Mon"] = Monday;
        }
        if (waitlistDict[location][animal].ContainsKey("Tue"))
        {
            waitlistDict[location][animal]["Tue"] = Tuesday;
        }
        else
        {
            waitlistDict[location][animal]["Tue"] = Tuesday;
        }
    }
}

Answer 1

你可以直接在你的循环中填充字典

private Dictionary<string, Dictionary<string, Dictionary<string, string>>> zooDict =
     new Dictionary<string, Dictionary<string, Dictionary<string, string>>>();

while (reader.Read())
{
       var location = reader.GetString(0).Trim();
       var animal= reader.GetString(1).Trim();
       var Monday= reader.GetValue(1).ToString().Trim();
       var Tuesday= reader.GetValue(3).ToString().Trim();

       if(!zooDict.ContainsKey(location))
            zooDict[location] = new Dictionary<string, Dictionary<string, string>>();

       zooDict[location][animal] = new Dictionary<string, string>() 
       {
             { "MN", Monday },
             { "Tu", Tuesday }
       };
}

作为旁注，您可能需要考虑创建类来表示您的对象，将它们添加到字典或列表中，然后使用 Newtonsoft Json.net ( http://www.newtonsoft.com/json ) 对它们进行序列化，而不是对所有内容都使用字典。例如，您可以创建一个类:

public class Animal
{
     public string Name { get; set; }
     public int Monday { get; set; }
     public int Tuesday { get; set; }
}

var zooDict = new Dictionary<string, List<Animal>>();

// then in your while loop you do this 
if(!zooDict.ContainsKey(location))
    zooDict[location] = new List<Animal>();
zooDict[location].Add(new Animal() { /* fill Monday and Tuesday properties */ });

当然，您可以更进一步，创建一个具有属性 string Location 的类和 List<Animal> Animals , 并完全消除字典。我猜这取决于您的用例