Comma-delimited and dash-delimited text fields in MVC 4 - asp.net-mvc

Question

We have a Razor form in our web app. During a meeting with the clients, we learned that one of the fields in this form should accept input that is:
A list of comma-delimited numbers
including ranges of numbers expressed using dashes
For example, the end-users might enter 45,50-53,65 to represent the list of numbers 45, 50, 51, 52, 53, 65. I'm assuming that the textbox might contain arbitrary whitespace as well that should be ignored (so 45, 50-53, 65 would represent the same information).
How would I set up such a text box in MVC 4 using Razor? In particular,
How would I create the text box in my Razor view?
How would I represent the information in the text box in my model?
How would I data-bind the text box to the model?
How would I set up validation for the text box?

Answer 1

I would just create a normal textbox -- you're asking for a string of numbers
You could have the form value as a string, and then another property that is the parsed version of the string, int[].
Since it is a string, it can be posted as a string.
Use a regular expression for the validator.
For 2, you could do something like this in your model:
public string Numbers { get; set; }
public int[] ParsedNumbers
{
get
{
Func<int[], int[]> arrayToRange = (range) =>
{
if (range.Length == 1) return range;
int[] ret = new int[range[1] - range[0] + 1];
for (int i = 0; i < ret.Length; i++)
{
ret[i] = i + range[0];
}
return ret;
};
return this.Numbers
.Replace(" ", "")
.Split(',')
.SelectMany(n => arrayToRange(n.Split('-')
.Select(n2 => int.Parse(n2)).ToArray())).ToArray();
}
}
For 4, you could use this RegEx:
^(\d(\-\d)?(, ?)?)*$