JSON string to CSV and CSV to JSON conversion in c#

I was able to solve it by DeserializeObject to a datatable using Json.net, so want to post my own answer but will not mark it as accepted, if anyone have better way to do this.

To convert JSON string to DataTable

public static DataTable jsonStringToTable(string jsonContent)
        {
            DataTable dt = JsonConvert.DeserializeObject<DataTable>(jsonContent);
            return dt;
        }

To make CSV string

public static string jsonToCSV(string jsonContent, string delimiter)
        {
            StringWriter csvString = new StringWriter();
            using (var csv = new CsvWriter(csvString))
            {
                csv.Configuration.SkipEmptyRecords = true;
                csv.Configuration.WillThrowOnMissingField = false;
                csv.Configuration.Delimiter = delimiter;

                using (var dt = jsonStringToTable(jsonContent))
                {
                    foreach (DataColumn column in dt.Columns)
                    {
                        csv.WriteField(column.ColumnName);
                    }
                    csv.NextRecord();

                    foreach (DataRow row in dt.Rows)
                    {
                        for (var i = 0; i < dt.Columns.Count; i++)
                        {
                            csv.WriteField(row[i]);
                        }
                        csv.NextRecord();
                    }
                }
            }
            return csvString.ToString();
        }

Final Usage in Web API

string csv = jsonToCSV(content, ",");

                HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
                result.Content = new StringContent(csv);
                result.Content.Headers.ContentType = new MediaTypeHeaderValue("text/csv");
                result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = "export.csv" };
                return result;

I don't know if this is too late to report solution for your question. Just in case if you want to explore open source library to do the job, here is one

Cinchoo ETL makes it easy to convert JSON to csv with few lines of code

using (var r = new ChoJSONReader("sample.json"))
{
    using (var w = new ChoCSVWriter("sample.csv").WithFirstLineHeader())
    {
        w.Write(r);
    }
}

For more information / source, go to https://github.com/Cinchoo/ChoETL

Nuget package:

.NET Framework:

      Install-Package ChoETL.JSON

.NET Core:

      Install-Package ChoETL.JSON.NETStandard

Full Disclosure: I'm the author of this library.

Had the same problem recently and I believe there is a little bit more elegant solution using the System.Dynamic.ExpandoObject and CsvHelper. It is less code and hopefully the performance is similar or better compared to the DataTable.

    public static string JsonToCsv(string jsonContent, string delimiter)
    {
        var expandos = JsonConvert.DeserializeObject<ExpandoObject[]>(jsonContent);

        using (var writer = new StringWriter())
        {
            using (var csv = new CsvWriter(writer))
            {
                csv.Configuration.Delimiter = delimiter;

                csv.WriteRecords(expandos as IEnumerable<dynamic>);
            }

            return writer.ToString();
        }
    }