使用HttpClient下载CSV文件并使用CsvHelper即时处理

Question

我正在尝试使用HttpClient下载csv文件，并使用CsvHelper库进行处理

string url = "https://www.nseindia.com/api/allIndices?csv=true";
string useragent = @"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.105 Safari/537.36";

var httpclient = new HttpClient();

var request = new HttpRequestMessage(HttpMethod.Get, url);
var sendtask = httpclient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);
var response = sendtask.Result.EnsureSuccessStatusCode();
var httpStream = await response.Content.ReadAsStreamAsync();
StreamReader streamreader = new StreamReader(httpStream);

CsvReader futureoptionsreader = new CsvReader(streamreader, CultureInfo.CreateSpecificCulture("en-US"));
futureoptionsreader.Configuration.RegisterClassMap<MappingNSEIndexes>();
var list = futureoptionsreader.GetRecords<RawNSEIndexes>();
var number = list.Count();

以错误数据结束

CsvHelper.BadDataException: You can ignore bad data by setting BadDataFound to null.
   at CsvHelper.CsvParser.Read()
   at CsvHelper.CsvReader.Read()
   at CsvHelper.CsvReader.GetRecords[T]()+MoveNext()
   at System.Linq.Enumerable.Count[TSource](IEnumerable`1 source)
   at MIS.Equity.API.Controllers.BooksController.GetCompaniesAsync() in C:\Users\Ramesh\source\repos\MIS_Main\MarkertInfoSystem\MIS.Equity.API\Controllers\BooksController.cs:line 66
   at lambda_method(Closure , Object )
   at Microsoft.Extensions.Internal.ObjectMethodExecutorAwaitable.Awaiter.GetResult()
   at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.AwaitableResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)

这种方法正确吗？提前感谢

Answer 1

所以，你发布的代码有点...我无法编译它，所以我重写了它，使其在使用HttpClient时遵循一个通用的模式

var url = "https://www.nseindia.com/api/allIndices?csv=true";

using (var msg = new HttpRequestMessage(HttpMethod.Get, new Uri(url)))
{
    msg.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("text/csv"));
    using (var resp = await _client.SendAsync(msg))
    {
        resp.EnsureSuccessStatusCode();

        using (var s = await resp.Content.ReadAsStreamAsync())
        using (var sr = new StreamReader(s))
        using (var futureoptionsreader = new CsvReader(sr, CultureInfo.CurrentCulture))
        {
            futureoptionsreader.Configuration.RegisterClassMap<MappingNSEIndexes>();
            var list = futureoptionsreader.GetRecords<RawNSEIndexes>();
            var number = list.Count();
        }
    }
}

请记住，除非您添加Headers.Accept行，否则服务器不会返回任何数据。

其中一个主要问题是这一行：

var response = sendtask.Result.EnsureSuccessStatusCode();
var httpStream = await response.Content.ReadAsStreamAsync();

这甚至不能编译-- EnsureSuccessStatusCode返回void。因此，我假设您在尝试进行故障排除时修改了代码，然后复制并粘贴了代码。