Question

I need to validate a field’s value according to two different validation rules:

1. An object of my own which contains a regex and a range (for string it’s length range).
2. A list of possible values.

So I can do this:

public static bool Validate(string fieldValue, string fieldType, ValidationParameters validationParameters)
{
...
}    
public static bool Validate(string fieldValue, string fieldType, string[] possibleValues)
{
...
}  

But that requires the user to ungracefully if.
I can also do this:

public static bool Validate(string fieldValue, string fieldType, ValidationParameters validationParameters=null,string[] possibleValues=null)
{
...
}  

Now the user can just send he’s data, without redundant if, But I can’t make sure validationParameters or possibleValues (one of them) got a value.

Is there a third option, one in which the user won’t have to check which method he uses, but I won’t have to worry that he doesn’t send any of the two fields (in code, not documentation)?
If not, which way of the two above is better (less error-prone and more elegant)?

Thanks.

Answer 1

I personally would do two overloaded methods. The main reasoning for this is:

But I can’t make sure validationParameters or possibleValues (one of them) got a value.

Optional arguments, in my opinion, should be exactly that: optional. Making two optional arguments where one is required seems like a problematic design choice.

Your main reasoning for avoiding this seems to be:

But that requires the user to ungracefully if.

However, I don’t see the problem. The user is going to have to construct either the string collection (which, I personally, would either make IEnumerable<string> instead of string[], or do params string[] possibleValues) or the ValidationParameters. If they already need to construct the arguments to pass, adding an if conditional seems unnecessary (each path could just call the validation).