3 Ways to Convert DataTable to JSON String in ASP.NET C#

The following code will generate a JSON string. Here we are making a for loop over our DataTable rows and columns. Fetch the data (values) and append it to our JSONString StringBuilder. This is how our code looks.

public string DataTableToJSONWithStringBuilder(DataTable table)   
{  
    var JSONString = new StringBuilder();  
    if (table.Rows.Count > 0)   
    {  
        JSONString.Append("[");  
        for (int i = 0; i < table.Rows.Count; i++)   
        {  
            JSONString.Append("{");  
            for (int j = 0; j < table.Columns.Count; j++)   
            {  
                if (j < table.Columns.Count - 1)   
                {  
                    JSONString.Append("\"" + table.Columns[j].ColumnName.ToString() + "\":" + "\"" + table.Rows[i][j].ToString() + "\",");  
                }   
                else if (j == table.Columns.Count - 1)   
                {  
                    JSONString.Append("\"" + table.Columns[j].ColumnName.ToString() + "\":" + "\"" + table.Rows[i][j].ToString() + "\"");  
                }  
            }  
            if (i == table.Rows.Count - 1)   
            {  
                JSONString.Append("}");  
            }   
            else   
            {  
                JSONString.Append("},");  
            }  
        }  
        JSONString.Append("]");  
    }  
    return JSONString.ToString();  
}  

Method 2. Convert the DataTable to JSON using JavaScriptSerializer

Since we are using JavaScriptSerializer, we first need to import the System.Web.Script.Serialization namespace into our page as in the following code.

using System.Web.Script.Serialization;  

The JavaScriptSerializer class is used internally by the asynchronous communication layer to serialize and deserialize the data.

To serialize an object, use the Serialize method. To deserialize a JSON string, use the Deserialize or DeserializeObject methods.

Here we use the serialize method to get the JSON format data. So our code looks as in the following:

public string DataTableToJSONWithJavaScriptSerializer(DataTable table) 
{  
    JavaScriptSerializer jsSerializer = new JavaScriptSerializer();  
    List < Dictionary < string, object >> parentRow = 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]);  
        }  
        parentRow.Add(childRow);  
    }  
    return jsSerializer.Serialize(parentRow);  
}  

Method 3. Convert DataTable to JSON using JSON.Net DLL (Newtonsoft)

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

For this, first, we need to download JSON.Net DLL. We can download it from Nuget.org and then import the Newtonsoft.JSON namespace into our page as in the following code. JSON.NET is a popular high-performance JSON framework. NET.

using Newtonsoft.JSON;  
  
public string DataTableToJSONWithJSONNet(DataTable table) {  
   string JSONString=string.Empty;  
   JSONString = JSONConvert.SerializeObject(table);  
   return JSONString;  
}  

Output