/// <summary>
/// Creates a successful or a failed attempt, with a result.
/// </summary>
/// <typeparam name="T">The type of the attempted operation result.</typeparam>
/// <param name="success">A value indicating whether the attempt is successful.</param>
/// <param name="result">The result of the attempt.</param>
/// <returns>The attempt.</returns>
public static Attempt <T> If <T>(bool success, T result)
{
return(Attempt <T> .SucceedIf(success, result));
}
/// <summary>
/// Tries to convert the input object to the output type using TypeConverters. If the destination
/// type is a superclass of the input type, if will use <see cref="Convert.ChangeType(object,System.Type)"/>.
/// </summary>
/// <param name="input">The input.</param>
/// <param name="destinationType">Type of the destination.</param>
/// <returns></returns>
public static Attempt <object> TryConvertTo(this object input, Type destinationType)
{
// if null...
if (input == null)
{
// nullable is ok
if (destinationType.IsGenericType && destinationType.GetGenericTypeDefinition() == typeof(Nullable <>))
{
return(Attempt <object> .Succeed(null));
}
// value type is nok, else can be null, so is ok
return(Attempt <object> .SucceedIf(destinationType.IsValueType == false, null));
}
// easy
if (destinationType == typeof(object))
{
return(Attempt.Succeed(input));
}
if (input.GetType() == destinationType)
{
return(Attempt.Succeed(input));
}
// check for string so that overloaders of ToString() can take advantage of the conversion.
if (destinationType == typeof(string))
{
return(Attempt <object> .Succeed(input.ToString()));
}
// if we've got a nullable of something, we try to convert directly to that thing.
if (destinationType.IsGenericType && destinationType.GetGenericTypeDefinition() == typeof(Nullable <>))
{
var underlyingType = Nullable.GetUnderlyingType(destinationType);
//special case for empty strings for bools/dates which should return null if an empty string
var asString = input as string;
if (asString != null && string.IsNullOrEmpty(asString) && (underlyingType == typeof(DateTime) || underlyingType == typeof(bool)))
{
return(Attempt <object> .Succeed(null));
}
// recursively call into myself with the inner (not-nullable) type and handle the outcome
var nonNullable = input.TryConvertTo(underlyingType);
// and if sucessful, fall on through to rewrap in a nullable; if failed, pass on the exception
if (nonNullable.Success)
{
input = nonNullable.Result; // now fall on through...
}
else
{
return(Attempt <object> .Fail(nonNullable.Exception));
}
}
// we've already dealed with nullables, so any other generic types need to fall through
if (destinationType.IsGenericType == false)
{
if (input is string)
{
// try convert from string, returns an Attempt if the string could be
// processed (either succeeded or failed), else null if we need to try
// other methods
var result = TryConvertToFromString(input as string, destinationType);
if (result.HasValue)
{
return(result.Value);
}
}
//TODO: Do a check for destination type being IEnumerable<T> and source type implementing IEnumerable<T> with
// the same 'T', then we'd have to find the extension method for the type AsEnumerable() and execute it.
if (TypeHelper.IsTypeAssignableFrom(destinationType, input.GetType()) &&
TypeHelper.IsTypeAssignableFrom <IConvertible>(input))
{
try
{
var casted = Convert.ChangeType(input, destinationType);
return(Attempt.Succeed(casted));
}
catch (Exception e)
{
return(Attempt <object> .Fail(e));
}
}
}
var inputConverter = TypeDescriptor.GetConverter(input);
if (inputConverter.CanConvertTo(destinationType))
{
try
{
var converted = inputConverter.ConvertTo(input, destinationType);
return(Attempt.Succeed(converted));
}
catch (Exception e)
{
return(Attempt <object> .Fail(e));
}
}
if (destinationType == typeof(bool))
{
var boolConverter = new CustomBooleanTypeConverter();
if (boolConverter.CanConvertFrom(input.GetType()))
{
try
{
var converted = boolConverter.ConvertFrom(input);
return(Attempt.Succeed(converted));
}
catch (Exception e)
{
return(Attempt <object> .Fail(e));
}
}
}
var outputConverter = TypeDescriptor.GetConverter(destinationType);
if (outputConverter.CanConvertFrom(input.GetType()))
{
try
{
var converted = outputConverter.ConvertFrom(input);
return(Attempt.Succeed(converted));
}
catch (Exception e)
{
return(Attempt <object> .Fail(e));
}
}
if (TypeHelper.IsTypeAssignableFrom <IConvertible>(input))
{
try
{
var casted = Convert.ChangeType(input, destinationType);
return(Attempt.Succeed(casted));
}
catch (Exception e)
{
return(Attempt <object> .Fail(e));
}
}
return(Attempt <object> .Fail());
}
/// <summary>
/// Attempts to convert the input object to the output type.
/// </summary>
/// <remarks>This code is an optimized version of the original Umbraco method</remarks>
/// <param name="input">The input.</param>
/// <param name="target">The type to convert to</param>
/// <returns>The <see cref="Attempt{Object}"/></returns>
public static Attempt <object> TryConvertTo(this object input, Type target)
{
if (target == null)
{
return(Attempt <object> .Fail());
}
try
{
if (input == null)
{
// Nullable is ok
if (target.IsGenericType && GetCachedGenericNullableType(target) != null)
{
return(Attempt <object> .Succeed(null));
}
// Reference types are ok
return(Attempt <object> .SucceedIf(target.IsValueType == false, null));
}
var inputType = input.GetType();
// Easy
if (target == typeof(object) || inputType == target)
{
return(Attempt.Succeed(input));
}
// Check for string so that overloaders of ToString() can take advantage of the conversion.
if (target == typeof(string))
{
return(Attempt <object> .Succeed(input.ToString()));
}
// If we've got a nullable of something, we try to convert directly to that thing.
// We cache the destination type and underlying nullable types
// Any other generic types need to fall through
if (target.IsGenericType)
{
var underlying = GetCachedGenericNullableType(target);
if (underlying != null)
{
// Special case for empty strings for bools/dates which should return null if an empty string.
if (input is string inputString)
{
//TODO: Why the check against only bool/date when a string is null/empty? In what scenario can we convert to another type when the string is null or empty other than just being null?
if (string.IsNullOrEmpty(inputString) && (underlying == typeof(DateTime) || underlying == typeof(bool)))
{
return(Attempt <object> .Succeed(null));
}
}
// Recursively call into this method with the inner (not-nullable) type and handle the outcome
var inner = input.TryConvertTo(underlying);
// And if sucessful, fall on through to rewrap in a nullable; if failed, pass on the exception
if (inner.Success)
{
input = inner.Result; // Now fall on through...
}
else
{
return(Attempt <object> .Fail(inner.Exception));
}
}
}
else
{
// target is not a generic type
if (input is string inputString)
{
// Try convert from string, returns an Attempt if the string could be
// processed (either succeeded or failed), else null if we need to try
// other methods
var result = TryConvertToFromString(inputString, target);
if (result.HasValue)
{
return(result.Value);
}
}
// TODO: Do a check for destination type being IEnumerable<T> and source type implementing IEnumerable<T> with
// the same 'T', then we'd have to find the extension method for the type AsEnumerable() and execute it.
if (GetCachedCanAssign(input, inputType, target))
{
return(Attempt.Succeed(Convert.ChangeType(input, target)));
}
}
if (target == typeof(bool))
{
if (GetCachedCanConvertToBoolean(inputType))
{
return(Attempt.Succeed(CustomBooleanTypeConverter.ConvertFrom(input)));
}
}
var inputConverter = GetCachedSourceTypeConverter(inputType, target);
if (inputConverter != null)
{
return(Attempt.Succeed(inputConverter.ConvertTo(input, target)));
}
var outputConverter = GetCachedTargetTypeConverter(inputType, target);
if (outputConverter != null)
{
return(Attempt.Succeed(outputConverter.ConvertFrom(input)));
}
if (target.IsGenericType && GetCachedGenericNullableType(target) != null)
{
// cannot Convert.ChangeType as that does not work with nullable
// input has already been converted to the underlying type - just
// return input, there's an implicit conversion from T to T? anyways
return(Attempt.Succeed(input));
}
// Re-check convertables since we altered the input through recursion
if (input is IConvertible convertible2)
{
return(Attempt.Succeed(Convert.ChangeType(convertible2, target)));
}
}
catch (Exception e)
{
return(Attempt <object> .Fail(e));
}
return(Attempt <object> .Fail());
}
// returns an attempt if the string has been processed (either succeeded or failed)
// returns null if we need to try other methods
private static Attempt <object>?TryConvertToFromString(this string input, Type destinationType)
{
// easy
if (destinationType == typeof(string))
{
return(Attempt <object> .Succeed(input));
}
// null, empty, whitespaces
if (string.IsNullOrWhiteSpace(input))
{
if (destinationType == typeof(bool)) // null/empty = bool false
{
return(Attempt <object> .Succeed(false));
}
if (destinationType == typeof(DateTime)) // null/empty = min DateTime value
{
return(Attempt <object> .Succeed(DateTime.MinValue));
}
// cannot decide here,
// any of the types below will fail parsing and will return a failed attempt
// but anything else will not be processed and will return null
// so even though the string is null/empty we have to proceed
}
// look for type conversions in the expected order of frequency of use...
if (destinationType.IsPrimitive)
{
if (destinationType == typeof(int)) // aka Int32
{
int value;
if (int.TryParse(input, out value))
{
return(Attempt <object> .Succeed(value));
}
// because decimal 100.01m will happily convert to integer 100, it
// makes sense that string "100.01" *also* converts to integer 100.
decimal value2;
var input2 = NormalizeNumberDecimalSeparator(input);
return(Attempt <object> .SucceedIf(decimal.TryParse(input2, out value2), Convert.ToInt32(value2)));
}
if (destinationType == typeof(long)) // aka Int64
{
long value;
if (long.TryParse(input, out value))
{
return(Attempt <object> .Succeed(value));
}
// same as int
decimal value2;
var input2 = NormalizeNumberDecimalSeparator(input);
return(Attempt <object> .SucceedIf(decimal.TryParse(input2, out value2), Convert.ToInt64(value2)));
}
// fixme - should we do the decimal trick for short, byte, unsigned?
if (destinationType == typeof(bool)) // aka Boolean
{
bool value;
if (bool.TryParse(input, out value))
{
return(Attempt <object> .Succeed(value));
}
// don't declare failure so the CustomBooleanTypeConverter can try
return(null);
}
if (destinationType == typeof(short)) // aka Int16
{
short value;
return(Attempt <object> .SucceedIf(short.TryParse(input, out value), value));
}
if (destinationType == typeof(double)) // aka Double
{
double value;
var input2 = NormalizeNumberDecimalSeparator(input);
return(Attempt <object> .SucceedIf(double.TryParse(input2, out value), value));
}
if (destinationType == typeof(float)) // aka Single
{
float value;
var input2 = NormalizeNumberDecimalSeparator(input);
return(Attempt <object> .SucceedIf(float.TryParse(input2, out value), value));
}
if (destinationType == typeof(char)) // aka Char
{
char value;
return(Attempt <object> .SucceedIf(char.TryParse(input, out value), value));
}
if (destinationType == typeof(byte)) // aka Byte
{
byte value;
return(Attempt <object> .SucceedIf(byte.TryParse(input, out value), value));
}
if (destinationType == typeof(sbyte)) // aka SByte
{
sbyte value;
return(Attempt <object> .SucceedIf(sbyte.TryParse(input, out value), value));
}
if (destinationType == typeof(uint)) // aka UInt32
{
uint value;
return(Attempt <object> .SucceedIf(uint.TryParse(input, out value), value));
}
if (destinationType == typeof(ushort)) // aka UInt16
{
ushort value;
return(Attempt <object> .SucceedIf(ushort.TryParse(input, out value), value));
}
if (destinationType == typeof(ulong)) // aka UInt64
{
ulong value;
return(Attempt <object> .SucceedIf(ulong.TryParse(input, out value), value));
}
}
else if (destinationType == typeof(Guid))
{
Guid value;
return(Attempt <object> .SucceedIf(Guid.TryParse(input, out value), value));
}
else if (destinationType == typeof(DateTime))
{
DateTime value;
if (DateTime.TryParse(input, out value))
{
switch (value.Kind)
{
case DateTimeKind.Unspecified:
case DateTimeKind.Utc:
return(Attempt <object> .Succeed(value));
case DateTimeKind.Local:
return(Attempt <object> .Succeed(value.ToUniversalTime()));
default:
throw new ArgumentOutOfRangeException();
}
}
return(Attempt <object> .Fail());
}
else if (destinationType == typeof(DateTimeOffset))
{
DateTimeOffset value;
return(Attempt <object> .SucceedIf(DateTimeOffset.TryParse(input, out value), value));
}
else if (destinationType == typeof(TimeSpan))
{
TimeSpan value;
return(Attempt <object> .SucceedIf(TimeSpan.TryParse(input, out value), value));
}
else if (destinationType == typeof(decimal)) // aka Decimal
{
decimal value;
var input2 = NormalizeNumberDecimalSeparator(input);
return(Attempt <object> .SucceedIf(decimal.TryParse(input2, out value), value));
}
else if (destinationType == typeof(Version))
{
Version value;
return(Attempt <object> .SucceedIf(Version.TryParse(input, out value), value));
}
// E_NOTIMPL IPAddress, BigInteger
return(null); // we can't decide...
}