how to represent a list of U.S. States

Question

Trying to do TDD against FluentValidation and Looking for the proper way to represent a list of US States.

For example, I have an "Address" object.

I would like to write a test (and a FluentValidation rule) that declares the address invalid if it's not in a list of US States.

This is a finite list, only to include the 50 US States, so I think it should be something constant and not represented in a database.

What I'm wondering is, what is the most efficient way to store and validate/test against this? An enum, an array, a list object, what?

Answer 1

I'd go with keeping them in a constant string array...

//Define the constant array
const String[] TheStates = new String[] { "Alabama", "Arizona", ... };

//fluentvalidation rule
RuleFor(address => address.State).Must(theState => TheStates.Contains(theState));

Keeping them in an Enum would require some association between the state name and an integer value - it just doesn't sound as efficient. Or you'd have to use ToString() a lot or build some custom attribute for each item in your enum (I've seen a few examples of this - but then you're dealing with reflection, which isn't as performant).

I would consider a List only if you need some additional data with each state (e.g. Full Name, Abbreviation, Date Admitted, etc.).

Go with the simplest format that you can.

Hope this helps.

Answer 2

Use a static readonly array or HashSet.

A state can be represented by it's full name or it's abbreviation. Do you want to check for both? Also, a state can be validated by a zip code (I'm not sure if you want to do that though).

You could possibly have a static readonly single-array or a hashset containing both the full name and abbreviation, like this:

public static readonly string[] listOfStates = new string[]
    {
        "New York",
        "NY",
        // rest of states & abbreviations here...
    };

or

public static readonly HashSet<string> listOfStates = new HashSet<string>
    {
        "New York",
        "NY",
        // rest of states & abbreviations here...
    };

Both support the Contains syntax:

// Queryable like this:
bool stateMatch = listOfStates.Contains(stringValue);