当前有一个DataTable,但希望通过WebHandler将其流式传输给用户。FileHelpers有CommonEngine.DataTableToCsv(dt, "file.csv")。但是它将保存到文件中。如何将其保存到流中?当我知道高级列或它们不变时,我知道该怎么做,但是我想直接从数据表中生成列标题。
CommonEngine.DataTableToCsv(dt, "file.csv")
如果我知道这些列,就可以创建类:
[DelimitedRecord(",")] public class MailMergeFields { [FieldQuoted()] public string FirstName; [FieldQuoted()] public string LastName; }
然后使用FileHelperEngine并添加记录:
FileHelperEngine engine = new FileHelperEngine(typeof(MailMergeFields)); MailMergeFields[] merge = new MailMergeFields[dt.Rows.Count + 1]; // add headers merge[0] = new MailMergeFields(); merge[0].FirstName = "FirstName"; merge[0].LastName = "LastName"; int i = 1; // add records foreach (DataRow dr in dt.Rows) { merge[i] = new MailMergeFields(); merge[i].FirstName = dr["Forename"]; merge[i].LastName = dr["Surname"]; i++; }
最后写入流:
TextWriter writer = new StringWriter(); engine.WriteStream(writer, merge); context.Response.Write(writer.ToString());
不幸的是,由于我之前不知道各列,因此无法提前创建类。
您可以自己快速写一些东西:
public static class Extensions { public static string ToCSV(this DataTable table) { var result = new StringBuilder(); for (int i = 0; i < table.Columns.Count; i++) { result.Append(table.Columns[i].ColumnName); result.Append(i == table.Columns.Count - 1 ? "\n" : ","); } foreach (DataRow row in table.Rows) { for (int i = 0; i < table.Columns.Count; i++) { result.Append(row[i].ToString()); result.Append(i == table.Columns.Count - 1 ? "\n" : ","); } } return result.ToString(); } }
并测试:
public static void Main() { DataTable table = new DataTable(); table.Columns.Add("Name"); table.Columns.Add("Age"); table.Rows.Add("John Doe", "45"); table.Rows.Add("Jane Doe", "35"); table.Rows.Add("Jack Doe", "27"); var bytes = Encoding.GetEncoding("iso-8859-1").GetBytes(table.ToCSV()); MemoryStream stream = new MemoryStream(bytes); StreamReader reader = new StreamReader(stream); Console.WriteLine(reader.ReadToEnd()); }
编辑:关于您的评论:
这取决于您要csv格式化的方式,但是通常情况下,如果文本包含特殊字符,则要用双引号将其括起来,即:“ my,text”。您可以在创建csv的代码中添加检查以检查特殊字符,如果有的话,则将文本用双引号引起来。至于.NET 2.0,只需在您的类中将其创建为帮助方法,或在方法声明中删除this并按如下方式调用它即可:Extensions.ToCsv(table);