CODEWITHSUNDEEP
c#
JsonStatham
JsonStatham

Reputation: 10364

How to pass generic type down to static method

I have a generic method which will return a select list populated from an enum.

public static IEnumerable<SelectListItem> GetGenericEnumSelectList<T>()
{
     return (Enum.GetValues(typeof(T)).Cast<int>().Select(e => new SelectListItem() { Text = EnumExtensions.GetEnumDescription((ProductsEnum)e) , Value = e.ToString() })).ToList();
}

I have put a call to a static method I also have called GetEnumDescription, this expects an Enum. How can I pass in the current type rather than hard coding the type as I have done. So that if T is a different type of enum, it will be generic.

Something like:

public static IEnumerable<SelectListItem> GetGenericEnumSelectList<T>()
{
    return (Enum.GetValues(typeof(T)).Cast<int>().Select(e => new SelectListItem() { Text = EnumExtensions.GetEnumDescription((typeof(T))e) , Value = e.ToString() })).ToList();
}

EDIT

Signature of GetEnumDescription is 

public static string GetEnumDescription(Enum value)
{

///

}

Upvotes: 0

Views: 104

Answers (1)

MakePeaceGreatAgain
MakePeaceGreatAgain

Reputation: 37000

Unfortunately there´s no generic constraint for enums - at least not before C#7.3. So the following isn´t possible:

void SoSomething<T>(T myEnum) where T: Enum { }

You could add another constraint as mentioned here:

void SoSomething<T>(T myEnum) where T: struct, IConvertible{ }

However that won´t help you much.

However in your case there´s no need to cast at all, as your methods parameter is Enum. So you can simply cast e to Enum:

return (Enum.GetValues(typeof(T)).Cast<Enum>().Select(e => new SelectListItem { 
    Text = EnumExtensions.GetEnumDescription(e), 
    Value = Convert.ToInt32(e).ToString() 
})).ToList();

Bw aware on the cast to Enum. Otherwise you get the following error:

Cannot convert type int to System.Enum

Upvotes: 3

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