使用 csvhelper 庫編寫 csv 文件

Question

我正在使用以下代碼並收到異常，

 Exception thrown: 'CsvHelper.WriterException' in CsvHelper.dll on this line executed:

csv.WriteRecord(item);

這是更多的代碼：

using (var memoryStream = new MemoryStream())
{
    using (var writer = new StreamWriter(memoryStream))
    {
        using (var csv = new CsvHelper.CsvWriter(writer, System.Globalization.CultureInfo.CurrentCulture))
        {
            foreach (var item in csvData)
            {
                csv.WriteRecord(item); // Exception thrown here
            }
        }
    }

    var arr = memoryStream.ToArray();
    //js.SaveAs("people.csv", arr);  what type object is js? copied from the stackoverflow answer linked here
}

這是 csvData 代碼：

IEnumerable<DateLowHigh> csvData = stocks.candles
    .Select(c => new DateLowHigh
    {
        Time = c.datetime,
        Close = c.close,
        Low = c.low,
        High = c.high
    })
    .ToList();

我確實得到了 csvData。

這個 stackoverflow答案幫助我開始了。

Answer 1

我不知道為什么你需要使用 CsvHelper 當你可以很容易地用 IO 庫做同樣的事情時。

sing System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace ConsoleApplication1
{
    class Program
    {
        const string FILENAME = @"c:\temp\test.csv";
        static void Main(string[] args)
        {
            Stocks stocks = new Stocks();

            IEnumerable<DateLowHigh> csvData = stocks.candles.Select(c => new DateLowHigh
            {
                Time = c.datetime,
                Close = c.close,
                Low = c.low,
                High = c.high
            }).ToList();

            MemoryStream memoryStream = new MemoryStream();
            using (var writer = new StreamWriter(memoryStream))
            {
                string[] headers = {"Time", "Close", "Low", "High"};
                writer.WriteLine(string.Join(",", headers));
                foreach (var item in csvData)
                {
                    writer.WriteLine(string.Join(",", new string[] { item.Time.ToString(), item.Close, item.Low.ToString(), item.High.ToString() }));
                }  
            }
            memoryStream.Position = 0;
        }
    }
    public class Stocks
    {
        public List<Candle> candles { get; set; }
    }
    public class Candle
    {
        public DateTime datetime { get; set; }
        public string close { get; set; }        
        public int low { get; set; }
        public int high { get; set; }
    }
    public class DateLowHigh
    {
        public DateTime Time { get; set; }
        public string Close { get; set; }
        public int Low { get; set; }
        public int High { get; set; }
    }
}

Answer 2

回答關於js.SaveAs("people.csv", arr); js是什么類型的對象的問題js.SaveAs("people.csv", arr); 它很可能是Microsoft.JSInterop.IJSRuntime如這個Blazer HowTo 中所見。 您引用的 StackOverflow 問題可能是使用它來訪問他們可以在 C# 代碼中使用的 JavaScript。 如果您只想使用 CsvHelper 保存一個 CSV 文件，它可以很簡單：

using (var writer = new StreamWriter("path\\to\\file.csv"))
using (var csv = new CsvWriter(writer, CultureInfo.InvariantCulture))
{    
    csv.WriteRecords(csvData);
}

如果您仍然遇到錯誤，則需要使用 StackTrace 發布完整的異常以提供進一步幫助。