C＃（将数据集转换为多个CSV字符串，保留类型并转换回）

Question

I just ran into a problem. I was trying to serialize a DataSet into json and encrypt it using jose-jwt . But it didn't work, I don't know the reason, but when trying to retrieve, the data was blank.

What I need is a way to convert the DataSet to List of CSVs and get it back, but preserving the Column Types.

Answer 1

Then I come with this Code that I want to share, and ask if someone have an easier way to do it. (I'm here to learn after all)

It has an option that add an extra column for each column and only in header it writes the DataColumn.DataType.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading;

namespace Demo
{
    public static class Utilities
    {
        private static char separator = '|';

        public static List<string> ToCSV(this DataSet ds, bool withTypes = false)
        {    
            List<string> lResult = new List<string>();

            foreach (DataTable dt in ds.Tables)
            {
                StringBuilder sb = new StringBuilder();
                IEnumerable<string> columnNames = dt.Columns.Cast<DataColumn>().
                                                  Select(column => (column.ColumnName + (withTypes ? separator + column.DataType.ToString() : "")));
                sb.AppendLine(string.Join(separator.ToString(), columnNames));

                foreach (DataRow row in dt.Rows)
                {
                    IEnumerable<string> fields = row.ItemArray.Select(field => $"{field.ToString().Replace("\"", "\"\"").Replace(Environment.NewLine, " ")}{(withTypes ? separator + "" : "") }");
                    sb.AppendLine(string.Join(separator.ToString(), fields));
                }

                lResult.Add(sb.ToString());
            }

            return lResult;
        }

        public static DataSet CSVtoDataSet(this List<string> collectionCSV, bool withTypes = false) //, char separator = '|')
        {    
            var ds = new DataSet();

            foreach (var csv in collectionCSV)
            {
                var dt = new DataTable();

                var readHeader = false;
                var lines = csv.Split(new[] { Environment.NewLine }, StringSplitOptions.None);

                foreach (var line in lines)
                {
                    if (!readHeader)
                    {
                        readHeader = true;
                        List<string> splited = line.Split(separator).ToList();

                        for (int i = 0; i < splited.Count; i++)
                        {
                            var columnName = splited[i];
                            var columnType = typeof(string);

                            if (withTypes && splited.Count > 1)
                            {
                                i++;
                                if (lines.Count() > 1)
                                {
                                    columnType = Type.GetType(splited[i]);
                                }
                            }

                            dt.Columns.Add(new DataColumn { ColumnName = columnName, DataType = columnType, AllowDBNull = true });
                        }
                    }
                    else
                    {
                        var splitedRow = line.Split(separator).ToList();

                        List<object> currentRow = new List<object>();

                        for (int i = 0; i < splitedRow.Count; i++)
                        {
                            if (withTypes && splitedRow.Count > 1)
                            {
                                var inputValue = splitedRow[i];
                                var t = dt.Columns[i / 2].DataType;

                                TypeConverter typeConverter = TypeDescriptor.GetConverter(t);
                                object propValue = string.IsNullOrEmpty(inputValue) ? null : typeConverter.ConvertFromString(inputValue);

                                currentRow.Add(propValue);
                                i++;//Next (0/2)
                            }
                            else
                            {
                                currentRow.Add(splitedRow[i]);
                            }
                        }

                        if (!currentRow.All(x => string.IsNullOrEmpty(x.ToString())))
                            dt.Rows.Add(currentRow.ToArray());
                    }
                }

                ds.Tables.Add(dt);
            }

            return ds;
        }
    }
}