Complier error if function parameter string is not in allow list-CodePudding

I was wondering is there is some C#\Visual Studio magic where I can have a list of strings that form a allow list for parameter inputs into a function?

In other words I would have a list of strings [“Green”, “yellow”, “blue”] and a function void example(string colour);. If I try to do example("red"); I get a complier error.

Bonus point if I can read this list for a text file or something, but copy and paste is fine.

Thanks

EDIT: I have ended up using const string C_RED = "RED". I never noticed that intellisence will give you a list of const. This works well as I can just type C_ and it will give me the valid options.

CodePudding user response：

Store the string in the list collection. Then take out the corresponding value and pass it to the example method.

  static void Main(string[] args)
    {
        List<string> mList = new List<string>(){"Green", "Rellow", "blue"};

        mList.Add("Green");
        mList.Add("Rellow");
        mList.Add("blue");
        new Program().example(mList[2]);

    }

   
    public void example(string colour)
    {
        Console.WriteLine("colour："   colour);
    }

Hope it helps you.

CodePudding user response：

A analogy of the problem I faced and this is how I addressed it. I want to restrict the Action in a Controller to be executed only if the query parameters in the request has allowed values.

1. Created a custom Validation Attribute

public class ElementValidate : ValidationAttribute
    {
        public string[] element = { "GREEN","YELLOW","BLUE" };

        public override bool IsValid(object? value)
        {
           string user_input =  (value as string).ToUpper();
            if (element.Contains(user_input))
            { 
                  return true;
            }
            else
                return false;   

        }
    }

2. Place the Attribute over the action method for which it is to be checked.

   [ElementValidate]
    public void Sample1()
    {
      // Actual Logic Goes Here
    }

CodePudding user response：

Try this

enum colors {Green=1, yellow=2, blue=3};

void example(string colour)
        {
            //Convert month in enum;
            Enum.TryParse(colour, out colors givenColour);

            if (givenColour == 0)
                throw new Exception("Invalid colur");

            // your implementation
        }