我有以下方法:
public byte[] WriteCsvWithHeaderToMemory<T>(IEnumerable<T> records) where T : class
{
using (var memoryStream = new MemoryStream())
using (var streamWriter = new StreamWriter(memoryStream))
using (var csvWriter = new CsvWriter(streamWriter))
{
csvWriter.WriteRecords<T>(records);
return memoryStream.ToArray();
}
}
使用对象列表调用哪个 - 最终来自数据库,但由于某些东西不起作用,我只是填充静态集合。传递的对象如下:
using CsvHelper.Configuration;
namespace Application.Models.ViewModels
{
public class Model
{
[CsvField(Name = "Field 1", Ignore = false)]
public string Field1 { get; set; }
[CsvField(Name = "Statistic 1", Ignore = false)]
public int Stat1{ get; set; }
[CsvField(Name = "Statistic 2", Ignore = false)]
public int Stat2{ get; set; }
[CsvField(Name = "Statistic 3", Ignore = false)]
public int Stat3{ get; set; }
[CsvField(Name = "Statistic 4", Ignore = false)]
public int Stat4{ get; set; }
}
}
我要做的是将一个集合写入csv以便在MVC应用程序中下载。每次我尝试写入方法时,MemoryStream都会返回零长度并且没有传递给它。我以前用过这个,但由于某种原因它只是不起作用 - 我有点困惑。谁能指出我在这里做错了什么?
干杯
答案 0 :(得分:32)
你已经拥有了using
块,非常棒。那将为你冲洗你的作家。您可以稍微更改代码,以使其正常工作。
using (var memoryStream = new MemoryStream())
{
using (var streamWriter = new StreamWriter(memoryStream))
using (var csvWriter = new CsvWriter(streamWriter))
{
csvWriter.WriteRecords<T>(records);
} // StreamWriter gets flushed here.
return memoryStream.ToArray();
}
如果您打开AutoFlush
,则需要小心。这将在每次写入后刷新。如果您的流是网络流并通过网络传输,那将非常慢。
答案 1 :(得分:21)
在返回刷新writer / stream之前放置csvWriter.Flush();
。
streamWriter.Flush();
。留下原始解决方案,但添加此更正。
答案 2 :(得分:9)
csvWriter中没有刷新,刷新是在streamWriter中。什么时候叫
csvWriter.Dispose();
它将刷新流。 另一种方法是设置
streamWriter.AutoFlush = true;
每次都会自动刷新流。
答案 3 :(得分:7)
将所有这些放在一起(以及更正的注释),包括重置内存流位置,对我来说最终的解决方案是;
using (MemoryStream ms = new MemoryStream())
{
using (TextWriter tw = new StreamWriter(ms))
using (CsvWriter csv = new CsvWriter(tw))
{
csv.WriteRecords(errors); // Converts error records to CSV
tw.Flush(); // flush the buffered text to stream
ms.Seek(0, SeekOrigin.Begin); // reset stream position
Attachment a = new Attachment(ms, "errors.csv"); // Create attachment from the stream
// I sent an email here with the csv attached.
}
}
如果帮助别人!
答案 4 :(得分:4)
以下是工作示例:
void Main()
{
var records = new List<dynamic>{
new { Id = 1, Name = "one" },
new { Id = 2, Name = "two" },
};
Console.WriteLine(records.ToCsv());
}
public static class Extensions {
public static string ToCsv<T>(this IEnumerable<T> collection)
{
using (var memoryStream = new MemoryStream())
{
using (var streamWriter = new StreamWriter(memoryStream))
using (var csvWriter = new CsvWriter(streamWriter))
{
csvWriter.WriteRecords(collection);
} // StreamWriter gets flushed here.
return Encoding.ASCII.GetString(memoryStream.ToArray());
}
}
}
基于this回答。