Validate String Array In ASP.NET MVC

Question

I use ASP.NET MVC. How can i validate string array in my view model. Because "Required" attribute doesn't work with string array.

[DisplayName("Content Name")]
[Required(ErrorMessage = "Content name is required")]
public string[] ContentName { get; set; }

How do you want to validate the array ? It must be at least one element ? Or every element should be not null or empty ? — Paul DS
– Paul DS, Commented Nov 3, 2015 at 9:19
Implement IValidatableObject on the model and perform custom validation in there. Alternatively do it within your controller and record the errors using ModelState.AddModelError() — Luke
– Luke, Commented Nov 3, 2015 at 9:25

Paul DS · Accepted Answer · 2015-11-03 09:37:44Z

10

You can create a custom validation attribute : http://www.codeproject.com/Articles/260177/Custom-Validation-Attribute-in-ASP-NET-MVC

public class StringArrayRequiredAttribute : ValidationAttribute
{
    protected override ValidationResult IsValid (object value, ValidationContext validationContext)
    {
        string[] array = value as string[];

        if(array == null || array.Any(item => string.IsNullOrEmpty(item)))
        {
            return new ValidationResult(this.ErrorMessage);
        }
        else
        {
            return ValidationResult.Success;
        }
    }
}

Then you can use like this :

[DisplayName("Content Name")]
[StringArrayRequired(ErrorMessage = "Content name is required")]
public string[] ContentName { get; set; }

answered Nov 3, 2015 at 9:37

Paul DS

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Comments

Taivan Amgalan · Accepted Answer · 2015-11-03 09:26:07Z

1

You should use custom validate

[HttpPost]
    public ActionResult Index(TestModel model)
    {
        for (int i = 0; i < model.ContentName.Length; i++)
        {
            if (model.ContentName[i] == "")
            {
                ModelState.AddModelError("", "Fill string!");
                return View(model);
            }
        }
        return View(model);
    }

answered Nov 3, 2015 at 9:26

Taivan Amgalan

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2 Comments

Luke Over a year ago

You need to check for null before doing the for loop

Taivan Amgalan Over a year ago

Our goal not check null value. Need check empty string.

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