在 C# 中创建通用字典

Question

I am trying to add a Key value pair the key is a string and the value is a class. The whole is thing is accesses through a generic method. So when I do a search based on the Key I get the class value in the dictionary. But unfortunately the code I have written compile it gives the below error. TokenizeCardViewModel' is a type, which is not valid in the given context

So when I do something like this:

bool value = CreditCardDetailPathCollection().Contains(subPathValue)

I Should get true or false. So that I can later use the value of the dictonary to create instance of the class.

private Dictionary<string,T> CreditCardDetailPathCollection<T>() where T:class
{
   return new Dictionary<string,T>
   { 
      { "tokenize-card", TokenizeCardViewModel } 
   };
}

Answer 1

Try this code

private Dictionary<string, T> CreditCardDetailPathCollection<T>() where T : class
    {
        var obj = Activator.CreateInstance<T>(); 
        return new Dictionary<string, T>
        { 
            { "tokenize-card", obj } 
        };
    }

Below code will create the instance of the T

var obj = Activator.CreateInstance<T>();

This way you just need to call the CreditCardDetailPathCollection method like this

var dict = CreditCardDetailPathCollection<TokenizeCardViewModel>();

Answer 2

Let's see if I understand that problem.

1. You have a K/V pair which is actually a string / Type .
2. Given a key , you are returned a Type .
3. Given the type , you now create an instance of this type.

Here's some code that might help...

NOTE: I also made this little .NET Fiddle so you can see it in action

var myTypes = new Dictionary<string, Type>(StringComparer.OrdinalIgnoreCase);
myTypes.Add("Leia", typeof(User));

...

if (!myTypes.ContainsKey(key))
{
    Console.WriteLine($"Dictionary failed to contain the key: {key}");
    return;
}

var myType = myTypes[key];
Console.WriteLine($"Found the type: ${myType.ToString()}.");

try
{
    var something = Activator.CreateInstance(myType);
}
catch (Exception exception)
{
    Console.WriteLine($"Failed to create an instance of {myType.ToString()}. Why? Error Message: {exception.Message}");
}

Now this assumes that there is a default constructor for the class which you wish to dynamically create an instance of.