How to do Integer model validation in asp.net mvc 2

Question

I have a registration form and the user must enter the square footage of their house. I would like this value to be only an integer. Is there a way to validate this value using attributes asp.net mvc?

Bushmaster

Much easier to use a regex here: #5662069 – Absolutely

Answer 1

yes, it is, but you will have to make a flat version of the object you are wanting to create, because the validation with attributes only runs AFTER MVC has converted your data into the model. which, when your value is an int, will fail to validate if the user did not enter an int, and you will get a MVC error message in stead of your errormessage.

can you post the object you are wanting to make?

with a flat version i mean all datetimes and ints are stings in the flat version.

then i use this:

    [DisplayName("Square meters")]
    [PosNumberNoZero(ErrorMessage = "need a positive number, bigger than 0")]
    public string squaremeters { get; set; }

in the same file

public class PosNumberNoZeroAttribute : ValidationAttribute {
    public override bool IsValid(object value) {
        if (value == null) {
            return true;
        }
        int getal;
        if (int.TryParse(value.ToString(), out getal)) {

            if (getal == 0)
                return false;

            if (getal > 0)
                return true;
        }
        return false;

    }
}

if my modelstate is valid then, i use AutoMapper to convert my FlatModel into my Model, which is just 2 lines of code.

edit: if 0 is a valid number:

public class PosNumberAttribute : ValidationAttribute {
    public override bool IsValid(object value) {
        if (value == null) {
            return true;
        }
        int getal;
        if (int.TryParse(value.ToString(), out getal)) {

            if (getal >= 0)
                return true;
        }
        return false;
    }
}

Ramon

sorry. for the trouble I should have known that. Just had a brain fart – Bushmaster

Why not use decimal.TryParse or something? In that way, you can support more number types than just integers – Bocanegra

Answer 2

Realise this has already been answered, but Stefanvds' answer is uneccessarily complicated. Just use MVCs built in validation attributes:

[DisplayName("Square Feet")]
[Required(ErrorMessage = "Square Feet is Required")]
[Range(0, int.MaxValue, ErrorMessage = "Square Feet must be a positive number")]
public int SquareFeet { get; set; }

Olander

For Range, system has a ErrorMessage "The field XXX must be between XXX and XXX." So the ErrorMessage is optional – Amphetamine

Yes, you are correct. But the custom ErrorMessage is a lot more user friendly than: "The field Square Feet must be between 0 and 2147483647". ;) – Olander

At least in MVC2 this does not work if the data passed in is not a valid integer. The framework will pass in the default value which is 0 and the validation will succeed, but later fail when the framework goes to actually instantiate the model and sees it cannot convert the data into an integer. It puts up the default error message at that point. – Irv

Answer 3

I usually use the range attribute like this:

Positive int:

[Range(0,int.MaxValue)]
public int Id { get; set; }

Negative int:

[Range(int.MinValue,-1)]
public int Id { get; set; }

Any int:

[Range(int.MinValue,int.MaxValue)]
public int Id { get; set; }

Clique

Zero - is not a positive integer. – Connective