Is there a way to get a type's alias through r

Question

I'm writing a simple code generation application to build POCO's from a DB2 database schema. I know it doesn't matter, but I prefer to use type aliases rather than the actual system type name if they are available, i.e., "int" rather than "Int32." Is there a way using reflection that I can get a type's alias rather than it's the actual type?

//Get the type name
var typeName = column.DataType.Name;

//If column.DataType is, say, Int64, I would like the resulting property generated
//in the POCO to be...

public long LongColumn { get; set; }

//rather than what I get now using the System.Reflection.MemberInfo.Name property:

public Int64 LongColumn { get; set; }

Thanks in advance.

Answer 1

public string GetAlias(Type t)
{
    string typeName = "";
    using (var provider = new CSharpCodeProvider())
    {
        var typeRef = new CodeTypeReference(t);
        typeName = provider.GetTypeOutput(typeRef);
    }
    return typeName;
}

Answer 2

I don't think there is. The alias is completly a compile time concept specific to the paticular .NET language you use. Once you reflect and view the type you will see the true .NET type of the object.

Answer 3

Based on the above 2 answers for using a Dictionary, I've written 2 basic extension methods that might help clean up the use a bit. Including this class in your project you will be able to use it simply by calling the Alias() or AliasOrName() methods on the type as shown below.

Example usage;

        // returns int
        string intAlias = typeof(Int32).Alias();
        // returns int
        string intAliasOrName = typeof(Int32).AliasOrName();
        // returns string.empty
        string dateTimeAlias = typeof(DateTime).Alias();
        // returns DateTime
        string dateTimeAliasOrName = typeof(DateTime).AliasOrName();

The implementation;

public static class TypeExtensions
{
    public static string Alias(this Type type)
    {
        return TypeAliases.ContainsKey(type) ?
            TypeAliases[type] : string.Empty;
    }

    public static string AliasOrName(this Type type)
    {
        return TypeAliases.ContainsKey(type) ?
            TypeAliases[type] : type.Name;
    }

    private static readonly Dictionary<Type, string> TypeAliases = new Dictionary<Type, string>
    {
        { typeof(byte), "byte" },
        { typeof(sbyte), "sbyte" },
        { typeof(short), "short" },
        { typeof(ushort), "ushort" },
        { typeof(int), "int" },
        { typeof(uint), "uint" },
        { typeof(long), "long" },
        { typeof(ulong), "ulong" },
        { typeof(float), "float" },
        { typeof(double), "double" },
        { typeof(decimal), "decimal" },
        { typeof(object), "object" },
        { typeof(bool), "bool" },
        { typeof(char), "char" },
        { typeof(string), "string" },
        { typeof(void), "void" },
        { typeof(byte?), "byte?" },
        { typeof(sbyte?), "sbyte?" },
        { typeof(short?), "short?" },
        { typeof(ushort?), "ushort?" },
        { typeof(int?), "int?" },
        { typeof(uint?), "uint?" },
        { typeof(long?), "long?" },
        { typeof(ulong?), "ulong?" },
        { typeof(float?), "float?" },
        { typeof(double?), "double?" },
        { typeof(decimal?), "decimal?" },
        { typeof(bool?), "bool?" },
        { typeof(char?), "char?" }
    };
}

Answer 4

Nope - just create a Dictionary<Type,string> to map all of the types to their aliases. It's a fixed set, so it's not hard to do:

private static readonly Dictionary<Type, string> Aliases =
    new Dictionary<Type, string>()
{
    { typeof(byte), "byte" },
    { typeof(sbyte), "sbyte" },
    { typeof(short), "short" },
    { typeof(ushort), "ushort" },
    { typeof(int), "int" },
    { typeof(uint), "uint" },
    { typeof(long), "long" },
    { typeof(ulong), "ulong" },
    { typeof(float), "float" },
    { typeof(double), "double" },
    { typeof(decimal), "decimal" },
    { typeof(object), "object" },
    { typeof(bool), "bool" },
    { typeof(char), "char" },
    { typeof(string), "string" },
    { typeof(void), "void" }
};

Answer 5

Keep it simple:

var aliasDict = new Dictionary<Type, string>() {
    { typeof(int), "int" },
    { typeof(long), "long" },
    // etc
}

Type reflectedType;
string aliasedTypeName = aliasDict[reflectedType];

Answer 6

This doesn't use reflection, strictly speaking, but you can get to the type's alias by using CodeDOM:

Type t = column.DataType;    // Int64

string typeName;
using (var provider = new CSharpCodeProvider())
{
    var typeRef = new CodeTypeReference(t);
    typeName = provider.GetTypeOutput(typeRef);
}

Console.WriteLine(typeName);    // long

(Having said that, I think that the other answers suggesting that you just use a mapping from CLR types to C# aliases are probably the best way to go with this one.)