ObjectExtensionsConvertTTarget(Object, CultureInfo) Method

Converts an Object specified in the obj parameter to the desired TTarget.

Definition

Namespace: KGySoft.CoreLibraries
Assembly: KGySoft.CoreLibraries (in KGySoft.CoreLibraries.dll) Version: 8.0.0
C#
public static TTarget Convert<TTarget>(
	this Object? obj,
	CultureInfo culture = null
)

Parameters

obj  Object
The object to convert.
culture  CultureInfo  (Optional)
The culture to use for the conversion. If , then the InvariantCulture will be used. This parameter is optional.
Default value: .

Type Parameters

TTarget
The desired type of the return value.

Return Value

TTarget
An object of TTarget, which is the result of the conversion.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type Object. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

Remarks

The method firstly tries to use registered direct conversions between source and target types, then attempts to perform the conversion via IConvertible types and registered TypeConverters. If these attempts fail, then the registered conversions tried to be used for intermediate steps, if possible. As an ultimate fallback, the String type is attempted to be used as intermediate conversion.

New conversions can be registered by the RegisterConversion extension methods.

A TypeConverter can be registered by the RegisterTypeConverter extension method.

  Tip

The registered conversions are tried to be used for intermediate conversion steps if possible. For example, if a conversion is registered from DateTime to Int64, then conversions from DateTime to Double becomes automatically available using the Int64 type as an intermediate conversion step.

TTarget can be even a collection type if obj is also an IEnumerable implementation. The target collection type must have either a default constructor or a constructor that can accept a list, array or dictionary as an initializer collection.

Example

C#
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;

using KGySoft.CoreLibraries;

public class Example
{
    public static void Main()
    {
        // between convertible types: like the Convert class but supports also enums in both ways
        ConvertTo<int>("123"); // culture can be specified, default is InvariantCulture
        ConvertTo<float>(ConsoleColor.Blue);
        ConvertTo<ConsoleColor>(13); // this would fail by Convert.ChangeType

        // TypeConverters are used if possible:
        ConvertTo<Guid>("AADC78003DAB4906826EFD8B2D5CF33D");

        // As a fallback, string is used as an intermediate step
        ConvertTo<DateTimeOffset>(DateTime.Now); // DateTime -> string -> DateTimeOffset

        // Collection conversion is also supported:
        ConvertTo<bool[]>(new List<int> { 1, 0, 0, 1 });
        ConvertTo<List<int>>("Blah"); // works because string is an IEnumerable<char>
        ConvertTo<string>(new[] { 'h', 'e', 'l', 'l', 'o' }); // because string has a char[] constructor
        ConvertTo<ReadOnlyCollection<string>>(new[] { 1.0m, 2, -1 }); // via the IList<T> constructor

        // even between non-generic collections:
        ConvertTo<ArrayList>(new HashSet<int> { 1, 2, 3 });
        ConvertTo<Dictionary<ConsoleColor, string>>(new Hashtable { { 1, "One" }, { "Black", 'x' } });

        // New conversions can be registered:
        ConvertTo<long>(DateTime.Now); // fail
        typeof(DateTime).RegisterConversion(typeof(long), (obj, type, culture) => ((DateTime)obj).Ticks);
        ConvertTo<long>(DateTime.Now); // success

        // Registered conversions can be used as intermediate steps:
        ConvertTo<double>(DateTime.Now); // DateTime -> long -> double
    }

    private static void ConvertTo<T>(object source)
    {
        Console.Write($"{source.GetType().GetName(TypeNameKind.ShortName)} => {typeof(T).GetName(TypeNameKind.ShortName)}: {AsString(source)} => ");
        try
        {
            T result = source.Convert<T>(); // a culture can be specified here for string conversions
            Console.WriteLine(AsString(result));
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message.Replace(Environment.NewLine, " "));
        }
    }

    private static string AsString(object obj)
    {
        if (obj == null)
            return "<null>";

        // KeyValuePair has a similar ToString to this one
        if (obj is DictionaryEntry de)
            return $"[{de.Key}, {de.Value}]";

        if (obj is not IEnumerable || obj is string)
            return obj.ToString();

        return ((IEnumerable)obj).Cast<object>().Select(AsString).Join(", ");
    }
}

// This example produces the following output:
// String => Int32: 123 => 123
// ConsoleColor => Single: Blue => 9
// Int32 => ConsoleColor: 13 => Magenta
// String => Guid: AADC78003DAB4906826EFD8B2D5CF33D => aadc7800-3dab-4906-826e-fd8b2d5cf33d
// DateTime => DateTimeOffset: 10/11/2021 7:45:46 PM => 10/11/2021 7:45:46 PM +02:00
// List`1[Int32] => Boolean[]: 1, 0, 0, 1 => True, False, False, True
// String => List`1[Int32]: Blah => 66, 108, 97, 104
// Char[] => String: h, e, l, l, o => hello
// Decimal[] => ReadOnlyCollection`1[String]: 1.0, 2, -1 => 1.0, 2, -1
// HashSet`1[Int32] => ArrayList: 1, 2, 3 => 1, 2, 3
// Hashtable => Dictionary`2[ConsoleColor,String]: [1, One], [Black, x] => [DarkBlue, One], [Black, x]
// DateTime => Int64: 10/11/2021 7:45:46 PM => The specified argument cannot be converted to type System.Int64. Parameter name: obj
// DateTime => Int64: 10/11/2021 7:45:46 PM => 637695783464721787
// DateTime => Double: 10/11/2021 7:45:46 PM => 6.37695783464721787E+17

Exceptions

ArgumentExceptionobj cannot be converted to TTarget.

See Also