/// <summary>
/// Converts value from one type to another using an optional <see cref="T:System.IFormatProvider" />.
/// </summary>
/// <param name="value">The original value.</param>
/// <param name="type">The target type.</param>
/// <param name="provider">A <see cref="T:System.IFormatProvider" /> used to format or parse the value.</param>
/// <param name="format">Format string.</param>
/// <param name="returnDbNUllIfNotValid">
/// Indicates whether exceptions should be avoided or catched and return value should be DBNull if
/// it cannot be converted to the target type.
/// </param>
/// <returns>The new value in the target type.</returns>
public static object ChangeType(
object value,
Type type,
IFormatProvider provider,
string format,
bool returnDbNUllIfNotValid)
{
var underlyingType = Nullable.GetUnderlyingType(type);
if (underlyingType != null)
{
value = ChangeType(value, underlyingType, provider, true);
return(NullableHelperInternal.FixDbNUllasNull(value, type));
}
if (value != null && !type.IsAssignableFrom(value.GetType()))
{
try
{
if (value is string)
{
value = format == null || format.Length <= 0
? Parse((string)value, type, provider, "", returnDbNUllIfNotValid)
: Parse((string)value, type, provider, format, returnDbNUllIfNotValid);
}
else if (!(value is DBNull))
{
if (type.GetTypeInfo().IsEnum)
{
value = Convert.ChangeType(value, typeof(int), provider);
value = Enum.ToObject(type, (int)value);
}
else
{
value = !(type == typeof(string)) || value is IConvertible
?
NullableHelperInternal.ChangeType(value, type, provider)
: value != null
? value.ToString()
: "";
}
}
}
catch
{
if (returnDbNUllIfNotValid)
{
return(DBNull.Value);
}
throw;
}
}
if ((value == null || value is DBNull) && type == typeof(string))
{
return("");
}
return(value);
}
/// <summary>
/// Parse the given text using the resultTypes "Parse" method or using a type converter.
/// </summary>
/// <param name="s">The text to parse.</param>
/// <param name="resultType">The requested result type.</param>
/// <param name="provider">A <see cref="T:System.IFormatProvider" /> used to format or parse the value. Can be NULL.</param>
/// <param name="formats">
/// A string array holding permissible formats used in a <see cref="M:System.Object.ToString" /> call. Right now
/// formats is only interpreted to enable roundtripping for formatted dates.
/// </param>
/// <param name="returnDbNUllIfNotValid">
/// Indicates whether DbNull should be returned if value cannot be parsed. Otherwise
/// an exception is thrown.
/// </param>
/// <returns>The new value in the target type.</returns>
public static object Parse(
string s,
Type resultType,
IFormatProvider provider,
string[] formats,
bool returnDbNUllIfNotValid)
{
return(NullableHelperInternal.FixDbNUllasNull(
_Parse(s, resultType, provider, "", formats, returnDbNUllIfNotValid), resultType));
}