/// <summary>
/// Save a list, or an array of, type-T objects to a file.
/// </summary>
/// <typeparam name="T">User's object type.</typeparam>
/// <param name="list">An enumerable object providing CSV data source.</param>
/// <param name="csvpath">Path to a csv file.</param>
/// <param name="hc">See comments of enum HeaderCare.</param>
/// <param name="encoding">Text file encoding of the csv.</param>
/// <returns>CSV data lines written, not including the header line.</returns>
public static int SaveCsvFile <T>(IEnumerable <T> list, string csvpath,
HeaderCare hc = HeaderCare.None,
Encoding encoding = null)
where T : class, new()
{
int count = 0;
if (encoding == null)
{
encoding = System.Text.Encoding.Default;
}
string correct_header_line = CsvLiner <T> .HeaderLine();
using (StreamWriter textwriter = new StreamWriter(csvpath, false, encoding))
{
if ((hc & HeaderCare.Preserve) != 0)
{
textwriter.WriteLine(correct_header_line);
}
foreach (T tobj in list)
{
textwriter.WriteLine(CsvLiner <T> .Put(tobj));
count++;
}
} // using file
return(count);
}
/// <summary>
/// Load a csv file and return an iterator of objects of user-given type(T).
/// </summary>
/// <typeparam name="T">User's object type.</typeparam>
/// <param name="csvpath">Path to a csv file.</param>
/// <param name="hc">See comments of enum HeaderCare.</param>
/// <param name="encoding">Text file encoding of the csv.</param>
/// <returns></returns>
public static IEnumerable <T> LoadCsvFile <T>(string csvpath,
HeaderCare hc = HeaderCare.None,
Encoding encoding = null)
where T : class, new()
{
if (encoding == null)
{
encoding = System.Text.Encoding.Default;
}
string correct_header_line = CsvLiner <T> .HeaderLine();
var csvlines = File.ReadLines(csvpath, encoding);
using (var enumer = csvlines.GetEnumerator())
{
if (!enumer.MoveNext())
{
yield break;
}
string line0 = enumer.Current;
bool is_line0_header = (line0 == correct_header_line) ? true : false;
if ((hc & HeaderCare.Verify) != 0)
{
// Need verify CSV header
if (!is_line0_header)
{
string s = $"CSV file does not have required headerline.\r\n" +
$"CSV file:\r\n" +
$" {csvpath}\r\n" +
$"Required header line:\r\n" +
$" {correct_header_line}\r\n";
throw new CsvLinerException(s);
}
}
if ((hc & HeaderCare.Preserve) != 0) // user want to preserve first line
{
yield return(CsvLiner <T> .Get(line0));
}
if (!is_line0_header) // first line is not a csv header
{
yield return(CsvLiner <T> .Get(line0));
}
while (enumer.MoveNext())
{
yield return(CsvLiner <T> .Get(enumer.Current));
}
} // using enumerator
}
