общего назначения ToCsv() метод расширения:
- Поддерживает Int16/32/64, поплавок, двойной, десятичной, и все, что поддерживающий ToString()
- Дополнительный заказ присоединиться сепаратор
- Дополнительный пользовательский селектор
- Дополнительная спецификация null/empty handling (* Перегрузка() перегрузки)
Примеры использования:
"123".ToCsv() // "1,2,3"
"123".ToCsv(", ") // "1, 2, 3"
new List<int> { 1, 2, 3 }.ToCsv() // "1,2,3"
new List<Tuple<int, string>>
{
Tuple.Create(1, "One"),
Tuple.Create(2, "Two")
}
.ToCsv(t => t.Item2); // "One,Two"
((string)null).ToCsv() // throws exception
((string)null).ToCsvOpt() // ""
((string)null).ToCsvOpt(ReturnNullCsv.WhenNull) // null
Реализация
/// <summary>
/// Specifies when ToCsv() should return null. Refer to ToCsv() for IEnumerable[T]
/// </summary>
public enum ReturnNullCsv
{
/// <summary>
/// Return String.Empty when the input list is null or empty.
/// </summary>
Never,
/// <summary>
/// Return null only if input list is null. Return String.Empty if list is empty.
/// </summary>
WhenNull,
/// <summary>
/// Return null when the input list is null or empty
/// </summary>
WhenNullOrEmpty,
/// <summary>
/// Throw if the argument is null
/// </summary>
ThrowIfNull
}
/// <summary>
/// Converts IEnumerable list of values to a comma separated string values.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="values">The values.</param>
/// <param name="joinSeparator"></param>
/// <returns>System.String.</returns>
public static string ToCsv<T>(
this IEnumerable<T> values,
string joinSeparator = ",")
{
return ToCsvOpt<T>(values, null /*selector*/, ReturnNullCsv.ThrowIfNull, joinSeparator);
}
/// <summary>
/// Converts IEnumerable list of values to a comma separated string values.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="values">The values.</param>
/// <param name="selector">An optional selector</param>
/// <param name="joinSeparator"></param>
/// <returns>System.String.</returns>
public static string ToCsv<T>(
this IEnumerable<T> values,
Func<T, string> selector,
string joinSeparator = ",")
{
return ToCsvOpt<T>(values, selector, ReturnNullCsv.ThrowIfNull, joinSeparator);
}
/// <summary>
/// Converts IEnumerable list of values to a comma separated string values.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="values">The values.</param>
/// <param name="returnNullCsv">Return mode (refer to enum ReturnNullCsv).</param>
/// <param name="joinSeparator"></param>
/// <returns>System.String.</returns>
public static string ToCsvOpt<T>(
this IEnumerable<T> values,
ReturnNullCsv returnNullCsv = ReturnNullCsv.Never,
string joinSeparator = ",")
{
return ToCsvOpt<T>(values, null /*selector*/, returnNullCsv, joinSeparator);
}
/// <summary>
/// Converts IEnumerable list of values to a comma separated string values.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="values">The values.</param>
/// <param name="selector">An optional selector</param>
/// <param name="returnNullCsv">Return mode (refer to enum ReturnNullCsv).</param>
/// <param name="joinSeparator"></param>
/// <returns>System.String.</returns>
public static string ToCsvOpt<T>(
this IEnumerable<T> values,
Func<T, string> selector,
ReturnNullCsv returnNullCsv = ReturnNullCsv.Never,
string joinSeparator = ",")
{
switch (returnNullCsv)
{
case ReturnNullCsv.Never:
if (!values.AnyOpt())
return string.Empty;
break;
case ReturnNullCsv.WhenNull:
if (values == null)
return null;
break;
case ReturnNullCsv.WhenNullOrEmpty:
if (!values.AnyOpt())
return null;
break;
case ReturnNullCsv.ThrowIfNull:
if (values == null)
throw new ArgumentOutOfRangeException("ToCsvOpt was passed a null value with ReturnNullCsv = ThrowIfNull.");
break;
default:
throw new ArgumentOutOfRangeException("returnNullCsv", returnNullCsv, "Out of range.");
}
if (selector == null)
{
if (typeof(T) == typeof(Int16) ||
typeof(T) == typeof(Int32) ||
typeof(T) == typeof(Int64))
{
selector = (v) => Convert.ToInt64(v).ToStringInvariant();
}
else if (typeof(T) == typeof(decimal))
{
selector = (v) => Convert.ToDecimal(v).ToStringInvariant();
}
else if (typeof(T) == typeof(float) ||
typeof(T) == typeof(double))
{
selector = (v) => Convert.ToDouble(v).ToString(CultureInfo.InvariantCulture);
}
else
{
selector = (v) => v.ToString();
}
}
return String.Join(joinSeparator, values.Select(v => selector(v)));
}
public static string ToStringInvariantOpt(this Decimal? d)
{
return d.HasValue ? d.Value.ToStringInvariant() : null;
}
public static string ToStringInvariant(this Decimal d)
{
return d.ToString(CultureInfo.InvariantCulture);
}
public static string ToStringInvariantOpt(this Int64? l)
{
return l.HasValue ? l.Value.ToStringInvariant() : null;
}
public static string ToStringInvariant(this Int64 l)
{
return l.ToString(CultureInfo.InvariantCulture);
}
public static string ToStringInvariantOpt(this Int32? i)
{
return i.HasValue ? i.Value.ToStringInvariant() : null;
}
public static string ToStringInvariant(this Int32 i)
{
return i.ToString(CultureInfo.InvariantCulture);
}
public static string ToStringInvariantOpt(this Int16? i)
{
return i.HasValue ? i.Value.ToStringInvariant() : null;
}
public static string ToStringInvariant(this Int16 i)
{
return i.ToString(CultureInfo.InvariantCulture);
}
'' Список не имеет метод 'Select' в рамках 3.5 если я не хватает чего-то. –
ajeh
@ajeh: Вам, вероятно, не хватает инструкции 'using'. – jason
Какой конкретный импорт? – ajeh