CSV Helper не записывается в файл

Question

Я застрял, пытаясь заставить CSV Helper написать файл. Когда я запускаю DownloadRegistrantsCsv, он загружает файл с собственным именем и всем остальным, но он никогда ничего не пишет.

public async Task<Stream> GetDownloadStreamAsync(int id) 
{ 

    var memoryStream = new MemoryStream(); 
    var streamWriter = new StreamWriter(memoryStream); 
    var streamReader = new StreamReader(memoryStream); 
    var csvHelper = new CsvHelper.CsvWriter(streamWriter); 
    csvHelper.WriteRecord(new EventRegistrant { FirstName = "Max" }); 
    await memoryStream.FlushAsync(); 
    memoryStream.Position = 0; 

    return memoryStream; 
} 

public async Task<ActionResult> DownloadRegistrantsCsv(int id) 
{ 
    var @event = await _service.GetAsync(id, true); 
    if (@event == null) 
     return HttpNotFound(); 

    var stream = await _service.GetDownloadStreamAsync(id); 
    return File(stream, "application/txt", "test" + ".csv"); 
} 

Я также попытался просто использовать документацию для CSV Helper, и я даже не могу получить, что писать. Вот что я получил за это ...

// Copyright 2009-2015 Josh Close and Contributors 
// This file is a part of CsvHelper and is dual licensed under MS-PL and Apache 2.0. 
// See LICENSE.txt for details or visit http://www.opensource.org/licenses/ms-pl.html for MS-PL and http://opensource.org/licenses/Apache-2.0 for Apache 2.0. 
// http://csvhelper.com 
using System; 
using System.Collections; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Globalization; 
using System.IO; 
using System.Web.Script.Serialization; 
using CsvHelper.Configuration; 
using CsvHelper.TypeConversion; 

namespace CsvHelper.Example 
{ 
    class Program 
    { 
     private const string columnSeparator = ":"; 

     static void Main(string[] args) 
     { 
      //ReadRawFieldsByIndex(); 
      //ReadRawFieldsByName(); 
      //ReadFieldsByIndex(); 
      //ReadRecordsNoAttributes(); 
      //ReadRecordsWithAttributes(); 
      //ReadAllRecords(); 

      //WriteRawFields(); 
      //WriteFields(); 
      WriteRecordsNoAttributes(); 
      //WriteRecordsWithAttributes(); 
      WriteAllRecords(); 

      Console.ReadKey(); 
     } 

     public static void ReadRawFieldsByIndex() 
     { 
      Console.WriteLine("Raw fields by index:"); 

      using (var reader = new CsvReader(new StreamReader(GetDataStream(true, true)))) 
      { 
       while (reader.Read()) 
       { 
        Console.Write(reader.GetField(0) + columnSeparator); 
        Console.Write(reader.GetField(1) + columnSeparator); 
        Console.Write(reader.GetField(2) + columnSeparator); 
        Console.WriteLine(reader.GetField(3)); 
       } 
      } 
      Console.WriteLine(); 
     } 

     public static void ReadRawFieldsByName() 
     { 
      Console.WriteLine("Raw fields by name:"); 

      using (var reader = new CsvReader(new StreamReader(GetDataStream(true, true)))) 
      { 
       while (reader.Read()) 
       { 
        Console.Write(reader.GetField("String Column") + columnSeparator); 
        Console.Write(reader.GetField("Int Column") + columnSeparator); 
        Console.Write(reader.GetField("Guid Column") + columnSeparator); 
        Console.Write(reader.GetField("Does Not Exist Column") + columnSeparator); 
        Console.WriteLine(reader.GetField("Custom Type Column")); 
       } 
      } 
      Console.WriteLine(); 
     } 

     public static void ReadFieldsByIndex() 
     { 
      Console.WriteLine("Fields by index:"); 

      var customTypeTypeConverter = new CustomTypeTypeConverter(); 

      using (var reader = new CsvReader(new StreamReader(GetDataStream(true, true)))) 
      { 
       while (reader.Read()) 
       { 
        Console.Write(reader.GetField<string>(0) + columnSeparator); 
        Console.Write(reader.GetField<int>("Int Column") + columnSeparator); 
        Console.Write(reader.GetField<Guid>(2) + columnSeparator); 
        Console.WriteLine(reader.GetField<CustomType>(3, customTypeTypeConverter)); 
       } 
      } 
      Console.WriteLine(); 
     } 

     public static void ReadRecordsNoAttributes() 
     { 
      Console.WriteLine("Records no attributes:"); 

      using (var reader = new CsvReader(new StreamReader(GetDataStream(true, false)))) 
      { 
       while (reader.Read()) 
       { 
        Console.WriteLine(reader.GetRecord<CustomObject>()); 
       } 
      } 
      Console.WriteLine(); 
     } 

     public static void ReadRecordsWithAttributes() 
     { 
      Console.WriteLine("Records with attributes:"); 

      using (var reader = new CsvReader(new StreamReader(GetDataStream(true, true)))) 
      { 
       reader.Configuration.RegisterClassMap<CustomObjectWithMappingMap>(); 

       while (reader.Read()) 
       { 
        Console.WriteLine(reader.GetRecord<CustomObjectWithMapping>()); 
       } 
      } 
      Console.WriteLine(); 
     } 

     public static void ReadAllRecords() 
     { 
      Console.WriteLine("All records:"); 

      using (var reader = new CsvReader(new StreamReader(GetDataStream(true, false)))) 
      { 
       var records = reader.GetRecords<CustomObject>(); 
       foreach (var record in records) 
       { 
        Console.WriteLine(record); 
       } 
      } 
      Console.WriteLine(); 
     } 

     public static void WriteRawFields() 
     { 
      Console.WriteLine("Write raw fields"); 

      using (var memoryStream = new MemoryStream()) 
      using (var streamWriter = new StreamWriter(memoryStream)) 
      using (var streamReader = new StreamReader(memoryStream)) 
      using (var writer = new CsvWriter(streamWriter)) 
      { 
       writer.WriteField("String Column"); 
       writer.WriteField("Int Column"); 
       writer.WriteField("Guid Column"); 
       writer.WriteField("Custom Type Column"); 
       writer.NextRecord(); 

       writer.WriteField("one"); 
       writer.WriteField((1).ToString()); 
       writer.WriteField(Guid.NewGuid().ToString()); 
       writer.WriteField((new CustomType { First = 1, Second = 2, Third = 3 }).ToString()); 
       writer.NextRecord(); 

       memoryStream.Position = 0; 

       Console.WriteLine(streamReader.ReadToEnd()); 
      } 
      Console.WriteLine(); 
     } 

     public static void WriteFields() 
     { 
      Console.WriteLine("Write fields"); 

      using (var memoryStream = new MemoryStream()) 
      using (var streamWriter = new StreamWriter(memoryStream)) 
      using (var streamReader = new StreamReader(memoryStream)) 
      using (var writer = new CsvWriter(streamWriter)) 
      { 
       writer.WriteField("String Column"); 
       writer.WriteField("Int Column"); 
       writer.WriteField("Guid Column"); 
       writer.WriteField("Custom Type Column"); 
       writer.NextRecord(); 

       writer.WriteField("one"); 
       writer.WriteField(1); 
       writer.WriteField(Guid.NewGuid()); 
       writer.WriteField(new CustomType { First = 1, Second = 2, Third = 3 }); 
       writer.NextRecord(); 

       memoryStream.Position = 0; 

       Console.WriteLine(streamReader.ReadToEnd()); 
      } 
      Console.WriteLine(); 
     } 

     public static void WriteRecordsNoAttributes() 
     { 
      Console.WriteLine("Write records no attributes:"); 

      var records = new List<CustomObject> 
      { 
       new CustomObject 
       { 
        CustomTypeColumn = new CustomType 
        { 
         First = 1, 
         Second = 2, 
         Third = 3, 
        }, 
        GuidColumn = Guid.NewGuid(), 
        IntColumn = 1, 
        StringColumn = "one", 
       }, 
       new CustomObject 
       { 
        CustomTypeColumn = new CustomType 
        { 
         First = 4, 
         Second = 5, 
         Third = 6, 
        }, 
        GuidColumn = Guid.NewGuid(), 
        IntColumn = 2, 
        StringColumn = "two", 
       }, 
      }; 

      using (var memoryStream = new MemoryStream()) 
      using (var streamWriter = new StreamWriter(memoryStream)) 
      using (var streamReader = new StreamReader(memoryStream)) 
      using (var writer = new CsvWriter(streamWriter)) 
      { 
       foreach (var record in records) 
       { 
        writer.WriteRecord(record); 
       } 

       memoryStream.Position = 0; 

       Console.WriteLine(streamReader.ReadToEnd()); 
      } 
      Console.WriteLine(); 
     } 

     public static void WriteRecordsWithAttributes() 
     { 
      Console.WriteLine("Write records with attributes:"); 

      var records = new List<CustomObjectWithMapping> 
      { 
       new CustomObjectWithMapping 
       { 
        CustomTypeColumn = new CustomType 
        { 
         First = 1, 
         Second = 2, 
         Third = 3, 
        }, 
        GuidColumn = Guid.NewGuid(), 
        IntColumn = 1, 
        StringColumn = "one", 
       }, 
       new CustomObjectWithMapping 
       { 
        CustomTypeColumn = new CustomType 
        { 
         First = 4, 
         Second = 5, 
         Third = 6, 
        }, 
        GuidColumn = Guid.NewGuid(), 
        IntColumn = 2, 
        StringColumn = "two", 
       }, 
      }; 

      using (var memoryStream = new MemoryStream()) 
      using (var streamWriter = new StreamWriter(memoryStream)) 
      using (var streamReader = new StreamReader(memoryStream)) 
      using (var writer = new CsvWriter(streamWriter)) 
      { 
       foreach (var record in records) 
       { 
        writer.WriteRecord(record); 
       } 

       memoryStream.Position = 0; 

       Console.WriteLine(streamReader.ReadToEnd()); 
      } 
      Console.WriteLine(); 
     } 

     public static void WriteAllRecords() 
     { 
      Console.WriteLine("Write all records with attributes:"); 

      var records = new List<CustomObjectWithMapping> 
      { 
       new CustomObjectWithMapping 
       { 
        CustomTypeColumn = new CustomType 
        { 
         First = 1, 
         Second = 2, 
         Third = 3, 
        }, 
        GuidColumn = Guid.NewGuid(), 
        IntColumn = 1, 
        StringColumn = "one", 
       }, 
       new CustomObjectWithMapping 
       { 
        CustomTypeColumn = new CustomType 
        { 
         First = 4, 
         Second = 5, 
         Third = 6, 
        }, 
        GuidColumn = Guid.NewGuid(), 
        IntColumn = 2, 
        StringColumn = "two", 
       }, 
      }; 

      using (var memoryStream = new MemoryStream()) 
      using (var streamWriter = new StreamWriter(memoryStream)) 
      using (var streamReader = new StreamReader(memoryStream)) 
      using (var writer = new CsvWriter(streamWriter)) 
      { 
       writer.Configuration.RegisterClassMap<CustomObjectWithMappingMap>(); 
       writer.WriteRecords(records as IEnumerable); 

       memoryStream.Position = 0; 

       Console.WriteLine(streamReader.ReadToEnd()); 
      } 
      Console.WriteLine(); 
     } 

     public static MemoryStream GetDataStream(bool hasHeader, bool hasSpacesInHeaderNames) 
     { 
      var stream = new MemoryStream(); 
      var writer = new StreamWriter(stream); 

      if (hasHeader) 
      { 
       var header = hasSpacesInHeaderNames 
           ? "String Column,Int Column,Guid Column,Custom Type Column" 
           : "StringColumn,IntColumn,GuidColumn,CustomTypeColumn"; 
       writer.WriteLine(header); 
      } 
      writer.WriteLine("one,1,{0},1|2|3", Guid.NewGuid()); 
      writer.WriteLine("two,2,{0},4|5|6", Guid.NewGuid()); 
      writer.WriteLine("\"this, has a comma\",2,{0},7|8|9", Guid.NewGuid()); 
      writer.WriteLine("\"this has \"\"'s\",4,{0},10|11|12", Guid.NewGuid()); 
      writer.Flush(); 
      stream.Position = 0; 

      return stream; 
     } 

     public class CustomType 
     { 
      public int First { get; set; } 
      public int Second { get; set; } 
      public int Third { get; set; } 

      public override string ToString() 
      { 
       var serializer = new JavaScriptSerializer(); 
       return serializer.Serialize(this); 
      } 
     } 

     public class CustomTypeTypeConverter : ITypeConverter 
     { 
      public string ConvertToString(TypeConverterOptions options, object value) 
      { 
       var obj = (CustomType)value; 
       return string.Format("{0}|{1}|{2}", obj.First, obj.Second, obj.Third); 
      } 

      public object ConvertFromString(TypeConverterOptions options, string text) 
      { 
       var values = ((string)text).Split('|'); 

       var obj = new CustomType 
       { 
        First = int.Parse(values[0]), 
        Second = int.Parse(values[1]), 
        Third = int.Parse(values[2]), 
       }; 
       return obj; 
      } 

      public bool CanConvertFrom(Type type) 
      { 
       throw new NotImplementedException(); 
      } 

      public bool CanConvertTo(Type type) 
      { 
       throw new NotImplementedException(); 
      } 
     } 

     public class CustomObject 
     { 
      public CustomType CustomTypeColumn { get; set; } 
      public Guid GuidColumn { get; set; } 
      public int IntColumn { get; set; } 
      public string StringColumn { get; set; } 

      public override string ToString() 
      { 
       var serializer = new JavaScriptSerializer(); 
       return serializer.Serialize(this); 
      } 
     } 

     public class CustomObjectWithMapping 
     { 
      public CustomType CustomTypeColumn { get; set; } 

      public Guid GuidColumn { get; set; } 

      public int IntColumn { get; set; } 

      public string StringColumn { get; set; } 

      public string IgnoredColumn { get; set; } 

      //public override string ToString() 
      //{ 
      // var serializer = new JavaScriptSerializer(); 
      // return serializer.Serialize(this); 
      //} 
     } 

     public sealed class CustomObjectWithMappingMap : CsvClassMap<CustomObjectWithMapping> 
     { 
      public CustomObjectWithMappingMap() 
      { 
       Map(m => m.CustomTypeColumn).Name("Custom Type Column").Index(3).TypeConverter<CustomTypeTypeConverter>(); 
       Map(m => m.GuidColumn).Name("Guid Column").Index(2); 
       Map(m => m.IntColumn).Name("Int Column").Index(1); 
       Map(m => m.StringColumn).Name("String Column").Index(0); 
      } 
     } 
    } 
} 

Может ли кто-нибудь указать мне на то, что я могу потерять или сделать неправильно?

Answer 1

Если у вас есть DataTable вы можете преобразовать его в разлуке список Значения Comma строк, как это ...

/// <summary> 
/// Creates a comma separated value string from a datatable. 
/// </summary> 
public static string ToCSV(DataTable table) 
{ 
    StringBuilder csv = new StringBuilder(); 
    for(int i = 0; i < table.Columns.Count ;i++) // process the column headers 
    { 
     if (i > 0) 
      csv.Append(","); 
     csv.Append(_FormatToCSVField(table.Columns[i].ColumnName)); 
    } 
    if (table.Columns.Count > 0) 
     csv.Append("\r\n"); 
    for (int i = 0; i < table.Rows.Count; i++) // process the row data 
    { 
     for (int j = 0; j < table.Columns.Count; j++) // process each field in the data row. 
     { 
      if (j > 0) 
       csv.Append(","); 
      csv.Append(_FormatToCSVField(table.Rows[i][j].ToString())); 
     } 
     csv.Append("\r\n"); 
    } 
    return csv.ToString(); 
} 
private static string _FormatToCSVField(string unformattedField) 
{ 
    return "\"" + unformattedField.Replace("\"", "\"\"") + "\""; 
} 

Или, если вы не имеете DataTable; возьмите свой созданный список разделенных запятыми значений (CSV) строки «row1 column 1, row1 column2, row1 column3, \ r \ n, row2, colm1 ... и т. д.»

и сохраните его в CSV Файл, подобный этому ...

  //Your CSV String 
     string WhatToWrite = "row1 column 1, row1 column2, row1 column3, \r\n"; 

     //Convert your CSV String to byte[] 
     byte[] PutWhatToWriteIntoBytes = Encoding.GetEncoding("iso-8859-1").GetBytes(WhatToWrite); 

     //Write the byte[] to CSV readable by excel 
     string filename = "WhatYouWantToCallYourFile" + ".csv"; 
     Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"; 
     Response.AddHeader("content-disposition", filename.ToString()); 
     Response.Clear(); 
     Response.BinaryWrite(PutWhatToWriteIntoBytes); 
     Response.End(); 

Его действительно сложно выполнить весь ваш код. Что именно вы пытаетесь написать в CSV ... Получите это; проверьте, хорошо ли это. затем напишите в файл. определить, если вы пишете пустую строку, или если запись теряет строку