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[Solved] Class validation not working?

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Joan Vilariño asked on 11 May 2010, 10:58 AM

Hi there.

I have a ViewModel class where I need to validate one property based on the value of another.

I've found a solution using a Custom Validator for the class like this:

                    [AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = true)]         
            public sealed class ValidateValueForFormat: ValidationAttribute         
                {         
                    private const string _defaultErrorMessage = "bleh bleh bleh";         
                     
                    private readonly object _typeId = new object();         
                     
                    public ValidateValueForFormat(string formatProp, string valueProp)         
                        : base(_defaultErrorMessage)         
                    {         
                        FormatProp = formatProp;         
                        ValueProp = valueProp;         
                    }         
                     
                    public string FormatProp         
                    {         
                        get;         
                        private set;         
                    }         
                     
                    public string ValueProp         
                    {         
                        get;         
                        private set;         
                    }         
                     
                    public override object TypeId         
                    {         
                        get         
                        {         
                            return _typeId;         
                        }         
                    }         
                     
                    public override string FormatErrorMessage(string name)         
                    {         
                        return String.Format(CultureInfo.CurrentUICulture, ErrorMessageString);         
                    }         
                     
                    public override bool IsValid(object value)         
                    {         
                        bool result = true;         
                        PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(value);         
                        int format =         
                            (int)properties.Find(FormatProp, true /* ignoreCase */).GetValue(value);         
                        string value = properties.Find(Valor, true /* ignoreCase */).GetValue(value);         
                     
                        .......         
                     
                        here I check the value against the format and set "result" to true         
                        if ok or false if not ok...         
                        .......         
                     
                        return result;         
                    }         
                }         
                     

Then I place my validation in the ViewModel's class header like this :

                             
            [ValidateValueForFormat("Format","Value",ErrorMessage="The value doesn't fit  the format needed."]         
            public class MyViewModel         
            {         
                     
              public int Format  { get; set; }         
              public string Value {get; set; }         
                     
            }         

I bind a list of this class' objects to an ajax grid, and make it editable. When I edit the field "value" and click on update, the validation class gets called, the isvalid method returns false, the formaterrorstring method is also called, but don't matter the result, valid or invalid, the Update always gets successful and my property gets a value that wasn't supposed to get.

Does your grid support this kind of validations? I find weird that the validation actually gets called but the grid ignores the result...

Thanks!!

8 Answers, 1 is accepted

answered on 11 May 2010, 11:02 AM

Hello Joan Vilariño,

I am not sure I understand your case. Ajax editing relies on TryUpdateModel which should return false if validation fails for some reason. In the case of custom validation however the grid will not be able to display the error message when ajax bound. Does this work with server binding/editing?

Regards,
Atanas Korchev
the Telerik team

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answered on 11 May 2010, 11:18 AM

Ok... I explain it a little more. Here is my GridAction:

                            [GridAction]         
                    public ActionResult _editarGridCaracteristicas(long id)         
                    {         
                        var cara = _modelo.VMLocal.ListaCaracteristicas.FirstOrDefault(o => o.Id == id);         
                        if (cara != null)         
                        {         
                            var ok = TryUpdateModel(cara);         
                            // What shoudl I do if ok == false?         
                        }         
                        return         
                            View(new GridModel<LocalViewModel.LocalCaracteristicaVM> { Data = _modelo.VMLocal.ListaCaracteristicas });         
                    }         
                     

I have confirmed that ok gets false, cause the validation fails, what should I do when this happens? Should I return the GridModel as I'm doing atm or the GridAction should return anything else to make your grid at least not allow the "update"...

answered on 11 May 2010, 11:23 AM

Hello Joan Vilariño,

The grid does not currently support custom validation in ajax binding mode. That's because there is no way currently to tell what the error message was to the grid in order for it to stay in edit mode and display it. I this case the only workaround is to use server binding and editing.

Regards,
Atanas Korchev
the Telerik team

answered on 11 May 2010, 01:21 PM

Hello Joan Vilariño,

I am afraid I cannot think of any workaround which does not require major modifications of the grid source. I am not sure if ASP.NET MVC client validation is extensible. If it is - adding custom client validator should work with the grid as well.

Regards,
Atanas Korchev
the Telerik team