convert from SqlDataReader to JSON

Question

public string toJSON(SqlDataReader o)
{
    StringBuilder s = new StringBuilder();
    s.Append(\"[\");
    if (o.HasRows)
        while (o.Read())
            s.App         


        

Answer 1

add reference : System.Web.Extensions to project then

using System.Web.Script.Serialization;

in c# code, you can use write :

 var json = new JavaScriptSerializer().Serialize(obj);

Answer 2

I use this code, based on Jonathan's answer:

private IEnumerable<Dictionary<string, object>> ConvertToDictionary(IDataReader reader)
{
    var columns = new List<string>();
    var rows = new List<Dictionary<string, object>>();

    for (var i = 0; i < reader.FieldCount; i++)
    {
        columns.Add(reader.GetName(i));
    }

    while (reader.Read())
    {
        rows.Add(columns.ToDictionary(column => column, column => reader[column]));
    }

    return rows;
}

And then:

var rows = this.ConvertToDictionary(reader);

return JsonConvert.SerializeObject(rows, Formatting.Indented);

Answer 3

This can't be that hard. This is what I've done when I want to return search results to a web page as JSON.

First, have a class like this

public class SearchResult
{
    public string model_no { get; set; }
    public string result_text { get; set; }
    public string url { get; set; }
    public string image_url { get; set; }
}

and then have the code below.

        string sql_text = "select * from product_master where model_no like @search_string and active=1";
        SqlConnection connection = new SqlConnection(sql_constr);
        SqlCommand cmd = new SqlCommand(sql_text, connection);
        cmd.Parameters.AddWithValue("@search_string", "%" + search_string + "%");
        connection.Open();

        SqlDataReader rdr = cmd.ExecuteReader();

        List<SearchResult> searchresults = new List<SearchResult>();

        while (rdr.Read())
        {
            SearchResult sr = new SearchResult();
            sr.model_no = rdr["model_no"].ToString();
            sr.result_text = rdr["product_name"].ToString();
            sr.url = rdr["url_key"].ToString();

            searchresults.Add(sr);

        }
        connection.Close();

        //build json result
        return Json(searchresults, JsonRequestBehavior.AllowGet);

this works for me very well..

Answer 4

Since SQL Server 2016, Microsoft embedded this feature with sql queries. You can achieve it by using FOR JSON keyword at the end of your queries.

select * from table_example where somecolumn = somecondition FOR JSON AUTO

for more details and example you can go through this official documents Format JSON Output Automatically with AUTO Mode (SQL Server)

Here is the C# code example from Microsoft to get JSON string from SQL queries.

var queryWithForJson = "SELECT ... FOR JSON";
var conn = new SqlConnection("<connection string>");
var cmd = new SqlCommand(queryWithForJson, conn);
conn.Open();
var jsonResult = new StringBuilder();
var reader = cmd.ExecuteReader();
if (!reader.HasRows)
{
    jsonResult.Append("[]");
}
else
{
    while (reader.Read())
    {
        jsonResult.Append(reader.GetValue(0).ToString());
    }
}

Warning: This solution is only valid for SQL SERVER 2016 and higher.

Answer 5

Another option would be to use James Newton-King's excellent JSON.NET library - http://www.newtonsoft.com/json

Here's a quick example on how to use it to build up a collection and then output it as a JSON-serialized string:

using Newtonsoft.Json;

class Program
{
    static void Main(string[] args)
    {
        ArrayList objs = new ArrayList();

        //get the data reader, etc.
        while(o.Read())
        {
            objs.Add(new
            {
                Id = o["Id"],
                CN = o["CatName"],
                Ord = o["Ord"],
                Icon = o["Icon"]
            });
        }

        //clean up datareader

        Console.WriteLine(JsonConvert.SerializeObject(objs));
        Console.ReadLine();
    }
}

You could do the same with your looping by reading in each row of your SqlDataReader into an anonymous object and then use JSON.NET to serialize it to a string.

Hope this helps!

Answer 6

I made the following method where it converts any DataReader to JSON, but only for single depth serialization:

you should pass the reader, and the column names as a string array, for example:

String [] columns = {"CustomerID", "CustomerName", "CustomerDOB"};

then call the method

public static String json_encode(IDataReader reader, String[] columns)
    {
        int length = columns.Length;

        String res = "{";

        while (reader.Read())
        {
            res += "{";

            for (int i = 0; i < length; i++)
            {
                res += "\"" + columns[i] + "\":\"" + reader[columns[i]].ToString() + "\"";

                if (i < length - 1)
                    res += ",";
            }

            res += "}";
        }

        res += "}";

        return res;
    }