Validation using attributes in asp.net mvc is really nice. I have been using the [Range(min, max)] validator this far for checking values, like e.g.:
[Range(1, 10)]
public int SomeNumber { get; set; }
However - now I need to check the min and max condition separately. I expected to find attributes like these:
[MinValue(1, "Value must be at least 1")]
[MaxValue(10, "Value can't be more than 10")]
public int SomeNumber { get; set; }
Are there any predefined attributes for writing this? Or how do I achieve this?
This question is related to
asp.net-mvc-3
validation
Here is how I would write a validator for MaxValue
public class MaxValueAttribute : ValidationAttribute
{
private readonly int _maxValue;
public MaxValueAttribute(int maxValue)
{
_maxValue = maxValue;
}
public override bool IsValid(object value)
{
return (int) value <= _maxValue;
}
}
The MinValue Attribute should be fairly the same
jQuery Validation Plugin already implements min and max rules, we just need to create an adapter for our custom attribute:
public class MaxAttribute : ValidationAttribute, IClientValidatable
{
private readonly int maxValue;
public MaxAttribute(int maxValue)
{
this.maxValue = maxValue;
}
public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
{
var rule = new ModelClientValidationRule();
rule.ErrorMessage = ErrorMessageString, maxValue;
rule.ValidationType = "max";
rule.ValidationParameters.Add("max", maxValue);
yield return rule;
}
public override bool IsValid(object value)
{
return (int)value <= maxValue;
}
}
Adapter:
$.validator.unobtrusive.adapters.add(
'max',
['max'],
function (options) {
options.rules['max'] = parseInt(options.params['max'], 10);
options.messages['max'] = options.message;
});
Min attribute would be very similar.
A complete example of how this could be done. To avoid having to write client-side validation scripts, the existing ValidationType = "range" has been used.
public class MinValueAttribute : ValidationAttribute, IClientValidatable
{
private readonly double _minValue;
public MinValueAttribute(double minValue)
{
_minValue = minValue;
ErrorMessage = "Enter a value greater than or equal to " + _minValue;
}
public MinValueAttribute(int minValue)
{
_minValue = minValue;
ErrorMessage = "Enter a value greater than or equal to " + _minValue;
}
public override bool IsValid(object value)
{
return Convert.ToDouble(value) >= _minValue;
}
public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
{
var rule = new ModelClientValidationRule();
rule.ErrorMessage = ErrorMessage;
rule.ValidationParameters.Add("min", _minValue);
rule.ValidationParameters.Add("max", Double.MaxValue);
rule.ValidationType = "range";
yield return rule;
}
}
I don't think min/max validations attribute exist. I would use something like
[Range(1, Int32.MaxValue)]
for minimum value 1 and
[Range(Int32.MinValue, 10)]
for maximum value 10
Source: Stackoverflow.com