我一直试图让CSV Helper写入文件。当我运行DownloadRegistrantsCsv时，它会使用正确的名称和其他所有内容下载文件，但它从不向它写入任何内容。
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");
}
我也尝试过使用CSV Helper的文档，我甚至无法编写。这就是我得到的......
// 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);
}
}
}
}
有人能指出我可能遗失或做错的事吗？
答案 0 :(得分：1)
如果你有一个DataTable，你可以将它转换为逗号分隔值这样的字符串列表......
/// <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("\"", "\"\"") + "\"";
}
或者如果你没有DataTable;取你创建的逗号分隔值（CSV）字符串列表＆＃34; row1列1，row1 column2，row1 column3，\ r \ n，row2，colum1 ......等...＆＃34;
并将其保存为CSV文件，如下所示......
//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();
很难遵循所有代码。你究竟想要写一个CSV到底是什么...得到那个;检查它是否好。然后写入文件。确定你是在写一个空字符串，还是写作正在丢失字符串
答案 1 :(得分：0)
如果您仍想使用CSV Helper
，则刷新流编写器对我有用