14

我对 C# 和 .NET 还很陌生，但是我编写了这段代码来调用存储过程，然后我想获取返回的 DataTable 并将其转换为 JSON。

    SqlConnection con = new SqlConnection("connection string here");
    SqlDataAdapter da = new SqlDataAdapter();
    SqlCommand cmd = new SqlCommand("getDates", con);
    SqlParameter par = new SqlParameter("@PlaceID", SqlDbType.Int);
    par.Value = 42;
    da.SelectCommand = cmd;
    cmd.Parameters.Add(par);
    DataSet ds = new DataSet();
    DataTable dt = new DataTable();

    con.Open();

    try{
        cmd.CommandType = CommandType.StoredProcedure;
        da.Fill(ds);
    }

那么我的问题是最好/最简单的方法是什么？一个例子会很棒，因为我对此还是很陌生。

4

7 回答 7

23

尽管 JavaScriptSerializer (System.Web.Script.Serialization.JavaScriptSerializer) 无法将 DataTable 直接转换为 JSON，但可以将 DataTable 解压缩为 List，然后再进行序列化。

以下函数将任意 DataTable 转换为 JSON 字符串（无需事先了解字段名称或数据类型）：

public static string DataTableToJSON(DataTable table)
{
    var list = new List<Dictionary<string, object>>();

    foreach (DataRow row in table.Rows)
    {
        var dict = new Dictionary<string, object>();

        foreach (DataColumn col in table.Columns)
        {
            dict[col.ColumnName] = row[col];
        }
        list.Add(dict);
    }
    JavaScriptSerializer serializer = new JavaScriptSerializer();
    return serializer.Serialize(list);
}
于 2012-08-21T21:10:28.100 回答
14

您可以使用 JSON.NET 库： http: //json.codeplex.com/来序列化/反序列化 DataTable。

string json = JsonConvert.SerializeObject(table);

序列化为这样的东西：

[ { "Column1": "Row Value", "Column2": "2" } ]

如果您需要序列化有关 DataTable 的更多信息，例如列模式、主键、表名，那么您可以使用我写的自定义转换器：https ://github.com/chris-herring/DataTableConverter 。像这样使用它：

string json = JsonConvert.SerializeObject(table, new Serialization.DataTableConverter());
DataTable table = JsonConvert.DeserializeObject<DataTable>(json, new Serialization.DataTableConverter());

序列化为这样的东西：

{
    "TableName": "TestTable",
    "Columns": [
        {
            "AllowDBNull": false,
            "AutoIncrement": true,
            "AutoIncrementSeed": 2,
            "AutoIncrementStep": 1,
            "Caption": "PrimaryKey",
            "ColumnName": "PrimaryKey",
            "DataType": "Int32",
            "DateTimeMode": "UnspecifiedLocal",
            "DefaultValue": null,
            "MaxLength": -1,
            "Ordinal": 0,
            "ReadOnly": false,
            "Unique": true
        }
    ],
    "Rows": [
        [
            1
        ],
        [
            2
        ],
        [
            3
        ]
    ],
    "PrimaryKey": ["PrimaryKey"]
}
于 2013-03-28T02:39:19.083 回答
7

谢谢爱丽儿。你的回答很有帮助。这是一个基于您的答案的版本。

public string ReadToJson(SqlDataReader reader)
{
  List<string> cols = new List<string>(10);
  int ncols = reader.FieldCount;
  for (int i = 0; i < ncols; ++i)
  {
    cols.Add(reader.GetName(i));
  }
  StringBuilder sbJson = new StringBuilder("[");
  //process each row
  while (reader.Read())
  {
    sbJson.Append("{");
    foreach (string col in cols)
    {
      sbJson.AppendFormat("\"{0}\":{1}, ", col, reader[col]);
    }
    sbJson.Replace(", ", "},", sbJson.Length - 2, 2);
  }
  sbJson.Replace("},", "}]", sbJson.Length - 2, 2);
  return sbJson.ToString();
}
于 2012-01-23T00:03:45.060 回答
7

您应该使用数据阅读器而不是数据表。您的代码效率低下且有些难以阅读 - 您可能想要执行以下操作：

StringBuilder json = new StringBuilder();

using(SqlConnection cnn = new SqlConnection(your_connection_string)) 
{
    cnn.open();

    using(SqlCommand cmd = new SqlCommand("name_of_stored_procedure", cnn)) 
    {
        cmd.Paramters.AddWithValue("@Param", "value");

        using(SqlDataReader reader = cmd.ExecuteReader()) 
        {
            while(reader.Read()) 
            {
                json.AppendFormat("{{\"name\": \"{0}\"}}", reader["name"]);
            }
        }
    }

    cnn.close();
}

然后你可以json.ToString用来获取输出

于 2010-02-22T18:16:39.220 回答
3

Thank you Karl Wenzel. I had a problem where I could only receive data table from an old asmx webservice. Now I wrote a web page which can parse this DataTable and return it in JSON.

public static string DataTableToJSON(DataTable table)
{
    List<Dictionary<string, object>> list = new List<Dictionary<string, object>>();

    foreach (DataRow row in table.Rows)
    {
        Dictionary<string, object> dict = new Dictionary<string, object>();

        foreach (DataColumn col in table.Columns)
        {
            dict[col.ColumnName] = row[col];
        }
        list.Add(dict);
    }
    JavaScriptSerializer serializer = new JavaScriptSerializer();
    return serializer.Serialize(list);
}
于 2013-05-27T11:23:32.543 回答
3

不使用 javascript 序列化程序的另一种方法：

public static string DataTableToJSON(DataTable Dt)
            {
                string[] StrDc = new string[Dt.Columns.Count];

                string HeadStr = string.Empty;
                for (int i = 0; i < Dt.Columns.Count; i++)
                {

                    StrDc[i] = Dt.Columns[i].Caption;
                    HeadStr += "\"" + StrDc[i] + "\":\"" + StrDc[i] + i.ToString() + "¾" + "\",";

                }

                HeadStr = HeadStr.Substring(0, HeadStr.Length - 1);

                StringBuilder Sb = new StringBuilder();

                Sb.Append("[");

                for (int i = 0; i < Dt.Rows.Count; i++)
                {

                    string TempStr = HeadStr;

                    for (int j = 0; j < Dt.Columns.Count; j++)
                    {

                        TempStr = TempStr.Replace(Dt.Columns[j] + j.ToString() + "¾", Dt.Rows[i][j].ToString().Trim());
                    }
                    //Sb.AppendFormat("{{{0}}},",TempStr);

                    Sb.Append("{"+TempStr + "},");
                }

                Sb = new StringBuilder(Sb.ToString().Substring(0, Sb.ToString().Length - 1));

                if(Sb.ToString().Length>0)
                Sb.Append("]");

                return StripControlChars(Sb.ToString());

            } 
 //Function to strip control characters:

//A character that does not represent a printable character  but serves to initiate a particular action.

            public static string StripControlChars(string s)
            {
                return Regex.Replace(s, @"[^\x20-\x7F]", "");
            }
于 2014-01-11T13:25:22.073 回答
2

我使用 JavaScriptSerializer + LINQ

return new JavaScriptSerializer().Serialize(
  dataTable.Rows.Cast<DataRow>()
  .Select(row => row.Table.Columns.Cast<DataColumn>()
    .ToDictionary(col => col.ColumnName, col => row[col.ColumnName]))
  .ToList()
);
于 2016-01-23T09:30:46.370 回答