What is the best way of adding a greater than 0 validator on the client-side using MVC and data annotation?
You can't store a number bigger than what your underlying data type could hold so that fact that the Range attribute requires a max value is a very good thing. Remember that ∞
doesn't exist in the real world, so the following should work:
[Range(1, int.MaxValue, ErrorMessage = "Please enter a value bigger than {1}")]
public int Value { get; set; }
I found this answer looking to validate any positive value for a float/double. It turns out these types have a useful constant for 'Epsilon'
Represents the smallest positive System.Double value that is greater than zero.
[Required]
[Range(double.Epsilon, double.MaxValue)]
public double Length { get; set; }
You can create your own validator like this:
public class RequiredGreaterThanZero : ValidationAttribute
{
/// <summary>
/// Designed for dropdowns to ensure that a selection is valid and not the dummy "SELECT" entry
/// </summary>
/// <param name="value">The integer value of the selection</param>
/// <returns>True if value is greater than zero</returns>
public override bool IsValid(object value)
{
// return true if value is a non-null number > 0, otherwise return false
int i;
return value != null && int.TryParse(value.ToString(), out i) && i > 0;
}
}
Then include that file in your model and use it as an attribute like this:
[RequiredGreaterThanZero]
[DisplayName("Driver")]
public int DriverID { get; set; }
I commonly use this on dropdown validation. Note that because it's extending validationattribute you can customize the error message with a parameter.