MVC Validation Attribute

Question

How do you validate a class using Validation attributes when validating strongly typed view models.

Suppose you have a view model like so:

[PropertiesMustMatch("Admin.Password", "Admin.ConfirmPassword")]
public class AdminsEditViewModel
{
    public AdminsEditViewModel()
    {
        this.Admin = new Admin(); // this is an Admin class
    }

    public IEnumerable<SelectListItem> SelectAdminsInGroup { get; set; }


    public IEnumerable<SelectListItem> SelectAdminsNotInGroup { get; set; }

    public Admin Admin { get; set; }
}

I get null exception when on this line of PropertiesMustMatchAttribute

object originalValue = properties.Find(OriginalProperty,  true /* ignoreCase */).GetValue(value);

since Password field is a property of Admin class and NOT AdminsEditViewModel. How do I make it so that it will go so many levels deep until it does find property of Admin in the ViewModel AdminsEditViewModel? thanks

SLaks · Accepted Answer · 2011-01-16 14:54:49Z

1

You need to modify the PropertiesMustMatchAttribute class to parse the property name and search deeply.

This attribute is not part of the framework; it's included in the default MVC template (in AccountModels.cs)
You can therefore modify it to suit your needs.

Specifically, you would call name.Split('.'), then loop through splitted names and get the property values.
It would look something like

object GetValue(object obj, string properties) {
    foreach(strong prop in properties)
        obj = TypeDescriptor.GetProperties(obj)
                            .Find(prop, ignoreCase: true)
                            .GetValue(obj);
    }
    return obj;
}

edited Jan 16, 2011 at 14:54

answered Jan 16, 2011 at 14:39

SLaks

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2 Comments

ShaneKm Over a year ago

not sure how to do it. can you please provide more info on this. thanks

SLaks Over a year ago

@Shane: Here you go. (untested)

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