How to convert datatable to json format in c#

How to convert Datatable to JSON C#: This article explains how to convert DataTable to JSON string in Asp.net C#. ex. serialize DataTable to JSON array in C#.
For example, let’s say you have SQL database and now want to return SQL data to JSON in C# application ex. how to return JSON String from DataTable in Asp.net C#. There are 1 ways to achieve this task and that are: By using JavaScriptSerializer, By using Json.Net DLL ( newtonsoft )

public ActionResult convertjson()
        {
                SqlTransaction objTrans = null;
                string strConnString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString; // get it from Web.config file 
                SqlConnection objConn = new SqlConnection(strConnString);
                objConn.Open();
                objTrans = objConn.BeginTransaction();            

                SqlCommand cmd = new SqlCommand("select  * from test order by id desc", objConn, objTrans);
                SqlDataAdapter sda = new SqlDataAdapter(cmd);
                DataTable dt = new DataTable();
                sda.Fill(dt);
                objTrans.Commit();
                return Json(MRPLookup.DataTableToJSONWithJSONNet(dt), JsonRequestBehavior.AllowGet);
        }

Now in this method we will convert our C# Datatable to JSON using the Newtonsoft DLL.

public static string DataTableToJSONWithJSONNet(DataTable table)
        {
            string JSONString = string.Empty;
            JSONString = JsonConvert.SerializeObject(table);
            return JSONString;
        }

This technic explains how to convert a DataTable to JSON in ASP.NET C#. In any words how to return a JSON String from a DataTable in ASP.NET C#.
 In any words, how to serialize a 
DataTable to a JSON array in C#. 

public string DataTableToJSONJavaScriptSerializer(DataTable table) 
{  
    JavaScriptSerializer jsSerializer = new JavaScriptSerializer();  
    List < Dictionary < string, object >> pRow = new List < Dictionary < string, object >> ();  
    Dictionary < string, object > childRow;  
    foreach(DataRow row in table.Rows) 
    {  
        childRow = new Dictionary < string, object > ();  
        foreach(DataColumn col in table.Columns) 
        {  
            childRow.Add(col.ColumnName, row[col]);  
        }  
        pRow.Add(childRow);  
    }  
    return jsSerializer.Serialize(pRow);  
}  

Convert datatable to JSON using C#.net

public static object DataTableToJSON(DataTable table)
    {
        var lst= 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] = (Convert.ToString(row[col]));
            }
            lst.Add(dict);
        }
        JavaScriptSerializer serializer = new JavaScriptSerializer();
        return serializer.Serialize(lst);
    }

ExtensionMethods

public static string ToJson(this DataTable dt)
{
    List<Dictionary<string, object>> lst = new List<Dictionary<string, object>>();
    Dictionary<string, object> item;
    foreach (DataRow row in dt.Rows)
    {
            item = new Dictionary<string, object>();
                foreach (DataColumn col in dt.Columns)
                {
                    item.Add(col.ColumnName, (Convert.IsDBNull(row[col]) ? null : row[col]));       
        }
        lst.Add(item);
    }
        return Newtonsoft.Json.JsonConvert.SerializeObject(lst);
}

To access the convert datatable value in Json method

$.ajax({
        type: "POST",
        url: "/Services.asmx/MethodName",
        data: "{}",
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (data) {
            var parsed = $.parseJSON(data.d);
            $.each(parsed, function (i, jsondata) {
            $("#dividtodisplay").append("Title: " + jsondata.title + "<br/>" + "Latitude: " + jsondata.lat);
            });
        },
        error: function (XHR, errStatus, errorThrown) {
            var err = JSON.parse(XHR.responseText);
            errorMessage = err.Message;
            alert(errorMessage);
        }
    });

2020-02-02

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