Question

I have a viewmodel with two other models in it. Both have fields that are required(done with entity framework).

    public class featureModel
    {

        public FEATURE FEATURE { get; set; }


        public REQUIREMENTS REQUIREMENTS { get; set; }
    }

On my page I have a dropdownlist, which is populated like this

ViewBag.FEATURE_ID = new SelectList(db.FEATURE, "FEATURE_ID", "Name_");

on view

@Html.DropDownList("FEATURE_ID", "ADD FEATURE")

Which will be a dropdownlist of all the features found, and on the top a ADD FEATURE option(when this is selected, i have some js to show the fields the user should input). IF this option is selected, then the user would need to input certain fields, if not they should not(and the fields are hidden). When my page validates, it requires that this needs to be populated, which makes sense in terms of validation.

Is there a way that I can set a condition to ignore this validation if the dropdownlist is on a certain option?

Answer 1

You implement System.ComponentModel.DataAnnotations.IValidatableObject on your ViewModel and perform validation there:

public class featureModel : IValidatableObject
{
    public FEATURE FEATURE { get; set; }
    public REQUIREMENTS REQUIREMENTS { get; set; }
    public bool FeaturesRequired { get; set; }

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
        if (featuresRequired)
        {
            // do your feature check here
            if (FEATURE == null)
            {
                yield return new ValidationResult("You must enter a feature.");
            }
        }
    }
}

Have a hidden field on your view that provides a value for FeaturesRequired (you could do this with javascript so onchange of your drop down) which can then be checked on model validation.

IValidatable with unobtrusive ajax (client-side validation)

Have a look at this resource for validating IValidatableObject on client-side.