Question

我有一个Generic List对象，它在表下面作为自己的值。

CountryID | StateID | StateName
--------------------------------
    1     |  1      |  Alabama    
    1     |  2      |  California
    1     |  3      |  Florida
    1     |  4      |  Hawaii   
    2     |  5      |  London
    2     |  6      |  Oxford

我想根据该List对象创建JSON字符串。我想获得的JSON格式如下所示。

{           
    1: { '1': 'Alabama', '2': 'California', '3': 'Florida', '4': 'Hawaii' },
    2: { '5': 'London', '6': 'Oxford' }
};

我使用下面的类来生成JSON对象。

public static class JSONHelper
{
    public static string ToJSON(this object obj)
    {
        JavaScriptSerializer serializer = new JavaScriptSerializer();
        return serializer.Serialize(obj);
    }

    public static string ToJSON(this object obj, int recursionDepth)
    {
        JavaScriptSerializer serializer = new JavaScriptSerializer();
        serializer.RecursionLimit = recursionDepth;            
        return serializer.Serialize(obj);
    }
}

但是，当我调用ToJSON方法时，我得到的实际输出如下所示。

{
[

{"CountryID":1,"StateID":1,"StateName":"Alabama"},
{"CountryID":1,"StateID":2,"StateName":"California"},
{"CountryID":1,"StateID":3,"StateName":"Florida"},
{"CountryID":1,"StateID":4,"StateName":"Hawaii"},
{"CountryID":2,"StateID":5,"StateName":"London"},
{"CountryID":2,"StateID":6,"StateName":"Oxford"}

]
}

那么，有谁能请给我一些建议我怎样才能制作出我想要的JSON字符串格式？
每个建议都将不胜感激。

Answer 1

这似乎是一种简单的方法，可以使用LINQ选择字典，然后将字典对象发送到JavascriptSerializer ......

我们有：

var list = new[]
               {
                   new {CountryID = 1, StateID = 1, StateName = "Alabama"},
                   new {CountryID = 1, StateID = 2, StateName = "California"},
                   new {CountryID = 1, StateID = 3, StateName = "Florida"},
                   new {CountryID = 1, StateID = 4, StateName = "Hawaii"},
                   new {CountryID = 2, StateID = 5, StateName = "London"},
                   new {CountryID = 2, StateID = 6, StateName = "Oxford"}
               };

然后我们可以递归调用.ToDictionary来获得以下内容：

var d = list
    .GroupBy(x=>x.CountryID)
    .ToDictionary(g=> g.Key.ToString(), 
        g => g.ToDictionary(x => x.StateID.ToString(),x => x.StateName));

var serializer = new JavaScriptSerializer();
return serializer.Serialize(d);

返回您请求的JSON

注意：您必须在字典Keys上调用.ToString（），因为JavaScript Serializer似乎在Dictionarys上使用不是字符串的键失败...

Answer 2

您需要序列化字典而不是列表才能获得该JSON。鉴于这些类型定义：

public class Country
{
    public Country()
    {
        States = new List<State>();
    }
    public int         CountryID  { get; set; }
    public List<State> States     { get; set; }
}

public class State
{
    public int    StateID    { get; set; }
    public string StateName  { get; set; }
}

这个变量：

    var clist = new List<Country>();

我可以使用此代码序列化为您想要的格式：

    var d = clist.ToDictionary
        (k => k.CountryID.ToString(),
         e => e.States.ToDictionary(k2 => k2.StateID.ToString(),
                                    e2 => e2.StateName));

    Console.WriteLine("{0}",JSONHelper.ToJSON(d));

这使用属于LINQ的ToDictionary()扩展方法。

输出：

{"1":{"1":"Lzwuoge","2":"0lzpas"},"2":{"1":"Mqn3ul5k","2":"Kefzu"}}

Answer 3

将其转换为您指定格式的最简单方法是将自定义类转换为嵌套字典：

Dictionary<Int32,Dictionary<String, String>>

然后序列化该输出。

Dictionary<Int32,Dictionary<String, String>> countryDict= new Dictionary<Int32,Dictionary<String, String>>()
foreach(var item in myGenericList){
    Dictionary<Int32,Dictionary<String, String> stateDict = 
    countryDict[item.CountryID] ?? new Dictionary<Int32,Dictionary<String, String>>();
    stateDict.Add(item.StateID.ToString(),item.StateName) 
}

使用自定义格式序列化JSON字符串

3 个答案: