@MarkPflug 我需要讀取 45 - 85 列中的 12 列。這是來自多個 csv 檔案（數百個）。但問題是，很多時候某些 csv 資料檔案中會缺少一兩列。鑒于我使用 nuget 包sylvan csv reader，如何在 C# 中檢查 csv 檔案中缺少的列。這是一些代碼：
// Create a reader
CsvDataReader reader = CsvDataReader.Create(file, new CsvDataReaderOptions { ResultSetMode = ResultSetMode.MultiResult });
// Get column by name from csv. This is where the error occurs only in the files that have missing columns. I store these and then use them in a GetString(Ordinal).
reader.GetOrdinal("HomeTeam");
reader.GetOrdinal("AwayTeam");
reader.GetOrdinal("Referee");
reader.GetOrdinal("FTHG");
reader.GetOrdinal("FTAG");
reader.GetOrdinal("Division");
// There is more data here, but anyway you get the point.
// Here I run the reader and for each piece of data I run my database write method.
while (await reader.ReadAsync())
{
await AddEntry(idCounter.ToString(), idCounter.ToString(), attendance, referee, division, date, home_team, away_team, fthg, ftag, hthg, htag, ftr, htr);
}
我嘗試了以下方法：
// This still causes it to go out of bounds.
if(reader.GetOrdinal("Division") < reader.FieldCount)
// only if the ordinal exists then assign it in a temp variable
else
// skip this column (set the data in add entry method to "")
uj5u.com熱心網友回復：
查看源代碼，如果未找到列名或列名不明確，則 GetOrdinal 似乎會拋出。因此，我希望您可以這樣做：
int blah1Ord = -1;
try{ blah1Ord = reader.GetOrdinal("blah1"); } catch { }
int blah2Ord = -1;
try{ blah2Ord = reader.GetOrdinal("blah2"); } catch { }
while (await reader.ReadAsync())
{
var x = new Whatever();
if(blah1Ord > -1) x.Blah1 = reader.GetString(blah1Ord);
if(blah2Ord > -1) x.Blah2 = reader.GetString(blah2Ord);
}
依此類推，因此您可以有效地確定列是否存在 - 如果不存在，序號保持 -1 - 然后使用它來決定是否讀取該列
順便說一句，我一直在處理標題名稱不佳/拼寫錯誤/部分標題名稱的 CSV，我發現自己正在獲取列架構并在其中搜索部分內容，例如：
using var cdr = CsvDataReader.Create(sr);
var cs = await cdr.GetColumnSchemaAsync();
var sc = StringComparison.OrdinalIgnoreCase;
var blah1Ord = cs.FirstOrDefault(c => c.ColumnName.Contains("blah1", sc))?.ColumnOrdinal ?? -1;
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