Question

我想在第一行插入新的两行而不影响CSV文件中的现有数据。

E.g：现有的CSV文件格式：

Name      Address      Value
--------------------------------
abc       India        123
XXX       USA          456

需要在现有CSV文件列标题之前插入新行。 E.g：

    Line1-A  ---> Need to add this line before column.
    Line2-B  ---> Need to add this line before column.

    Name      Address      Value
    --------------------------------
    abc       India        123
    XXX       USA          456

我创建CSV文件的现有代码＆amp;使用此代码，我只能在列和行下面创建：

    Name      Address      Value
    --------------------------------
    abc       India        123
    XXX       USA          456

但需要在行上方添加两行。

using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace WindowsFormsApplication1
{
    public class CreateCSVFile
    {
        #region Create .csv File ANDON - DASHBOARD
        public void CreateFile(HistorianData objHistorian)
        {
            try
            {
                CreateCSVFile obj = new CreateCSVFile();
                StringBuilder sb = new StringBuilder();               

                DataTable dt = obj.GetData(objHistorian);


                foreach (DataRow dr in dt.Rows)
                {
                    foreach (DataColumn dc in dt.Columns)
                        sb.Append(obj.FormatCSV(dr[dc.ColumnName].ToString()) + ",");
                    sb.Remove(sb.Length - 1, 1);
                    sb.AppendLine();
                }

                //Create .csv File:
                string fileName = objHistorian.getTagName + "_" + "_" + DateTime.UtcNow.ToString("yyyy-MM-ddTHH_mm_ssZ") + ".csv";               
                string path = @"C:\Documents\" + fileName;



                if (!File.Exists(path))
                {
                    DataTableToCreateCSVFile(dt, path);                    
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("Error :" + ex.StackTrace, ex.Message);
            }
        }


        public DataTable GetData(HistorianData fields)
        {
            DataTable dt = new DataTable();
            dt.Columns.Add("Tagname", typeof(string));
            dt.Columns.Add("TimeStamp", typeof(string));
            dt.Columns.Add("Value", typeof(string));
            dt.Columns.Add("DataQuality", typeof(string));
            dt.Rows.Add(fields.getTagName, fields.timeStamp, fields.getPropertyValue, fields.dataQuality);
            return dt;
        }

        public string FormatCSV(string input)
        {
            try
            {
                if (input == null)
                    return string.Empty;

                bool containsQuote = false;
                bool containsComma = false;
                int len = input.Length;
                for (int i = 0; i < len && (containsComma == false || containsQuote == false); i++)
                {
                    char ch = input[i];
                    if (ch == '"')
                        containsQuote = true;
                    else if (ch == ',')
                        containsComma = true;
                }

                if (containsQuote && containsComma)
                    input = input.Replace("\"", "\"\"");

                if (containsComma)
                    return "\"" + input + "\"";
                else
                    return input;
            }
            catch
            {
                throw;
            }
        }

        public void DataTableToCreateCSVFile(DataTable dtDataTable, string strFilePath)
        {
            StreamWriter sw = new StreamWriter(strFilePath, false);
            //headers  
            for (int i = 0; i < dtDataTable.Columns.Count; i++)
            {
                sw.Write(dtDataTable.Columns[i]);
                if (i < dtDataTable.Columns.Count - 1)
                {
                    sw.Write(",");
                }
            }
            sw.Write(sw.NewLine);
            foreach (DataRow dr in dtDataTable.Rows)
            {
                for (int i = 0; i < dtDataTable.Columns.Count; i++)
                {
                    if (!Convert.IsDBNull(dr[i]))
                    {
                        string value = dr[i].ToString();
                        if (value.Contains(','))
                        {
                            value = String.Format("\"{0}\"", value);
                            sw.Write(value);
                        }
                        else
                        {
                            sw.Write(dr[i].ToString());
                        }
                    }
                    if (i < dtDataTable.Columns.Count - 1)
                    {
                        sw.Write(",");
                    }
                }
                sw.Write(sw.NewLine);
            }
            sw.Close();
        }

        #endregion
    }

    public class HistorianData
    {
        public string getTagName { get; set; }
        public DateTime timeStamp { get; set; }
        public string dataQuality { get; set; }
        public string getPropertyValue { get; set; }
    }

}

Answer 1

您可以尝试这种方法。使用MemoryStream附加新行，读取文件内容，然后将MemoryStream中的所有字节写入文件：

string filePath = @"C:\Test\test.csv";
string csvLine = "value1; value2; value3" + Environment.NewLine;
byte[] csvLineBytes = Encoding.Default.GetBytes(csvLine);
using (MemoryStream ms = new MemoryStream())
{
      ms.Write(csvLineBytes , 0, csvLineBytes.Length);
      using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read))
       {                        
           byte[] bytes = new byte[file.Length];
           file.Read(bytes, 0, (int)file.Length);
           ms.Write(bytes, 0, (int)file.Length);                    
        }

        using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Write))
        {
            ms.WriteTo(file);
        }
}

如何在不影响现有行的情况下将新行添加到现有CSV文件中

1 个答案: