转换数据表嵌套JSON在C＃

Question

我想数据表转换成嵌套的JSON，但得到以下错误：

"An item with the same key has already been added."

数据

CstCmpCode  Main_Group  Sub_Group ClosBal 
AH01   Neck Wraps  AFGHANI  7 

现在我想JSON结果是这样的：

{ 
    "CstCmpCode": "AH01", 
    "Main_Group": "Neck Wraps", 
    "sub_group": [ 
    { 
     "Sub_Group": "AFGHANI", 
     "ClosBal": 7 
    } 
    ] 
} 

我用下面的代码：

System.Web.Script.Serialization.JavaScriptSerializer serializer = new System.Web.Script.Serialization.JavaScriptSerializer(); 

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["TallyWeb"].ToString()); 
SqlCommand cmd = new SqlCommand(); 
cmd.CommandText = "select CstCmpCode, Loaded_date, Main_Group, Sub_Group, ClosBal from TlyStkSumm where CstCmpCode = @CstCmpCode"; 
cmd.Parameters.AddWithValue("@CstCmpCode", CstCmpCode); 
DataSet ds = new DataSet(); 
DataTable dt = new DataTable(); 
SqlDataAdapter da = new SqlDataAdapter(cmd); 
da.SelectCommand.Connection = con; 
da.Fill(dt); 
con.Close(); 

var main = new Dictionary<string, Dictionary<string, string>>(); 

foreach (DataRow rs in dt.Rows) 
{ 
    string Main_Group = rs["Main_Group"].ToString(); 
    Dictionary<string, string> sub; 
    if (!main.TryGetValue(Main_Group, out sub)) 
    { 
     sub = new Dictionary<string, string>(); 
     main.Add(Main_Group, sub); 
    } 

    sub.Add(rs["Sub_Group"].ToString(), (string)rs["ClosBal"]); 
} 

RootObject root = new RootObject { main = main }; 


public class RootObject 
{ 
    [JsonProperty("main")] 
    public Dictionary<string, Dictionary<string, string>> main { get; set; } 
} 

Answer 1

在你的代码在这里：

string Main_Group = rs["Main_Group"].ToString(); 
Dictionary<string, string> sub; 
if (!main.TryGetValue(Main_Group, out sub)) 
{ 
    sub = new Dictionary<string, string>(); 
    main.Add(Main_Group, sub); 
} 

sub.Add(rs["Sub_Group"].ToString(), (string)rs["ClosBal"]); 
      ^^^^^^^ 

我认为问题就在这里 - 你添加到sub字典rs["Sub_Group"]没有如果存在检查。所以如果你有相同的Sum_Group两倍于Main_group的值，它会抛出你得到的异常。