ReactiveUI and Validation - silverlight

Question

What's considered "best practice" when performing data validation while using ReactiveUI? Let's say I have a view model that looks like this:
public class MyViewModel: ReactiveObject
{
public ReactiveAsyncCommand SaveMyDataCommand { get; protected set; }
private string _email;
public string Email
{
get { return _email; }
set
{
_email = value;
raisePropertyChanged("Email");
}
}
private string _name;
public string Name
{
get { return _name; }
set
{
_name= value;
raisePropertyChanged("Name");
}
}
private bool _sendEmail = false;
public bool SendEmail
{
get { return _sendEmail; }
set
{
_sendEmail = value;
raisePropertyChanged("SendEmail");
}
}
public MyViewModel()
{
SaveMyDataCommand = new ReactiveAsyncCommand(null, 1);
}
}
Here's what I want to validate:
If SendEmail == true then make sure there's a valid email address in the Email property. (I'm not worried about the actual email address validation piece itself. This is just a what if scenario.)
If a value was set to the Email property, make sure it's a valid email address.
If either 1. or 2. fail validation, SaveMyDataCommand should not be executable.
I'm just looking for a good example on how to do simple / slightly more complex data validation using ReactiveUI. Can anyone shed some light on this?

Answer 1

For anyone else looking for an example on using ReactiveValidatedObject, here's what worked for me. Note that you'll have to add a reference to System.ComponentModel to your class as well.
public class MyViewModel: ReactiveValidatedObject
{
public ReactiveAsyncCommand SaveMyDataCommand { get; protected set; }
// THIS PROPERTY INDICATES WHETHER ALL FIELDS HAVE BEEN VALIDATED
public bool IsSaveEnabled
{
get { return IsObjectValid(); }
}
private string _email;
[ValidatesViaMethod(AllowBlanks=true,AllowNull=true,Name="IsEmailValid",ErrorMessage="Please enter a valid email address")]
public string Email
{
get { return _email; }
set
{
_email = value;
raisePropertyChanged("Email");
SendEmail = SendEmail;
raisePropertyChanged("IsSaveEnabled");
}
}
private string _name;
public string Name
{
get { return _name; }
set
{
_name= value;
raisePropertyChanged("Name");
}
}
private bool _sendEmail = false;
[ValidatesViaMethod(Name = "IsSendEmailValid", ErrorMessage = "Make sure a valid email address is entered.")]
public bool SendEmail
{
get { return _sendEmail; }
set
{
_sendEmail = value;
raisePropertyChanged("SendEmail");
raisePropertyChanged("IsSaveEnabled");
}
}
public bool IsEmailValid(string email)
{
if (string.IsNullOrEmpty(email))
{
return true;
}
// Return result of Email validation
}
public bool IsSendEmailValid(bool sendEmail)
{
if (sendEmail)
{
if (string.IsNullOrEmpty(Email))
{
return false;
}
// Return result of Email validation
}
}
public MyViewModel()
{
SaveMyDataCommand = new ReactiveAsyncCommand(null, 1);
}
}
I hope this helps someone! :)

Answer 2

Use ReactiveValidatedObject, then use Data Annotations (on phone, sorry for short message)