ASP.Net (3.5) MVC partial class for rule validation

Question

I have 2 projects. A data project, which contains my database and my Entity Framework model. I have table called 'User', and then have a generated EF class for user.

I am trying to add a partial class:

using System;
using System.Collections.Generic;
using System.Data.Linq;
using System.Linq;
using System.Text;

namespace Data
{
    public partial class user
    {

        public bool isValid
        {
            get {
                return (GetRuleViolations().Count()==0);
            }
        }

        public IEnumerable<RuleViolation> GetRuleViolations()
        {
            yield break;
        }



        partialvoid OnValidate(ChangeAction action)
        {
            if (isValid)
                throw new ApplicationException("Rule violation prevents saving");
        }
    }

    public class RuleViolation
    {
        public string ErrorMessage { get; private set; }
        public string PropertyName { get; private set; }

        public RuleViolation (string errorMessage)
        {
            ErrorMessage = errorMessage;
        }

        public RuleViolation(string errorMessage, string propertyName)
        {
            ErrorMessage = errorMessage;
            PropertyName = propertyName;
        }
    }
}

This is following the MVC 1.0 NerdDinner example. However, I am getting a design time error on the OnValidate method:

    partial void OnValidate(ChangeAction action)
    {
        if (isValid)
            throw new ApplicationException("Rule violation prevents saving");
    }

No definining declaration found for implimenting declaration of partial method 'void OnValidate(ChangeAction action)'

What am I doing wrong?

Answer 1

There should be another file containing the rest of the user class.

In this file you have to declare that there might be a partial method called OnValidate.

public partial class user
{
    partial void OnValidate(ChangeAction action);
}

Some detail: A partial method needs to have a signature specified somewhere. Once the signature has been defined then an optional implementation can be specified. Read http://msdn.microsoft.com/en-us/library/wa80x488.aspx for more information.