Create custom DataType Validation

Question

I want to make my own validation class (i have a lot of validation methods in JS that i want to translate into C# to use with MVC models) that works exactly like data annotations do, validating in client and server side: [DataType(MyDataType)] or like a Validation DataAnnotation Attribute like this: [MyDataTypeValidation]

i don't know wich option is better to make my validation "library"

In example i have my class FigurasDA and i want to make my custom validation to the attribute nombre.

namespace MonitoreoIntegrado.Models
{
    [MetadataType(typeof(FigurasDA))]
    public partial class Figuras
{
}

public class FigurasDA
{
    [DataType(MyDataType)]
    //or
    [MyDataTypeValidation]
    public string nombre { get; set; }
}
}

so in this case, i want to validate that the string matches the regexp @"^[\w\s\.\-_]+$" and shows a error message like this "Solo se permite letras, numeros y puntuaciones(- _ .)" if don't. (this is my "Alfanumerico" datatype).

Can you give me an example where to put my validation class and what code write inside?.

Have you tried the RegularExpressionAttribute ex:[RegularExpression(@"pattern", ErrorMessage="")]? Or you can extend one of the ValidationAttribute classes. — Jasen
– Jasen, Commented Jun 13, 2014 at 18:27
I want to use this regexp in a lot of classes. so i need a class i guess — Clamari
– Clamari, Commented Jun 13, 2014 at 18:33

Dmytro · Accepted Answer · 2014-06-13 18:45:50Z

11

Actually it's easy... You just have to inherit you custom validation attribute from ValidationAttribute class and provide your own IsValid logic. For example:

public class MyDataTypeValidationAttribute : ValidationAttribute
{
    private Regex _regex = new Regex(@"^[\w\s.-_]+$");          

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {               
        if (_regex.IsMatch(value.ToString()))
        {
            return ValidationResult.Success;
        }

        return new ValidationResult("Solo se permite letras, numeros y puntuaciones(- _ .)" );
    }
}

and in your view model you can use:

public class FigurasDA
{    
    [MyDataTypeValidation]
    public string nombre { get; set; }
}

You can save this validation attribute, for example in Attributes folder in your MVC project:

Step 1

Step 2

Step 3

edited Jun 13, 2014 at 18:45

answered Jun 13, 2014 at 18:30

Dmytro

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4 Comments

Dmytro Over a year ago

@Clamari, wherever you want in your solution/project. You can create folder named Attributes and put there all your custom validation logic.

Clamari Over a year ago

In a DataValidation.css file inside my project root IE?

Dmytro Over a year ago

@Clamari, css is cascade style sheet file, it contains html page styles. I provided some screen shots for example, see my edits.

Clamari Over a year ago

Sorry, was a typo. DataValidation.cs it was just an extra "s" haha thanks a lot :).

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