> Regards
> Marlon
> WPF Blog - http://marlongrech.wordpress.com/
> Microsoft MVP for Client App

> On Mon, Mar 15, 2010 at 3:12 PM, Peter O'Hanlon <pete.ohan...@gmail.com>wrote:

>> Sounds good. As far as the FocusScopes go, there shouldn't be any issues,
>> but it's an edge case to consider (I've been bitten too many times by custom
>> FocusScopes).

>> On Mon, Mar 15, 2010 at 3:08 PM, Josh Smith <flappleja...@gmail.com>wrote:

>>> Thanks Pete. I was thinking that there could be an attached property of
>>> type bool that is set on an element, instead of setting ValidatedProperty.
>>>  When set, that attached property figures out which property on the element
>>> to monitor, such as Text on a TextBox.  This would make it easier than
>>> having to specify the property, though that would still be an option if you
>>> need to specify it.

>>> I'll have to look into FocusScopes, though I don't see any issues there
>>> (I might be overlooking something...).

>>> Josh

>>> On Mon, Mar 15, 2010 at 6:31 AM, Peter O'Hanlon <pete.ohan...@gmail.com>wrote:

>>>> The only thing that stands out to me is that this is going to have to be
>>>> applied in a lot of places in a typical LOB application, so that might be a
>>>> little bit tedious. What effects do FocusScope's have here? I'll need to
>>>> play around with this a bit just to make sure there aren't any edge cases
>>>> that occur (I'm primarily thinking of cases where loss of focus to a
>>>> menu/toolbar triggers the validation but the parent FocusScope has changed
>>>> from the textbox).

>>>> Pete

>>>>   On Mon, Mar 15, 2010 at 2:24 PM, Josh Smith <flappleja...@gmail.com>wrote:

>>>>> Thanks.  Any pitfalls or gotchas sticking their heads out?

>>>>> On Mon, Mar 15, 2010 at 1:03 AM, Peter O'Hanlon <
>>>>> pete.ohan...@gmail.com> wrote:

>>>>>> I like it - I know that it feels "dirty", but it's actually pretty
>>>>>> darn cool.

>>>>>>  On Mon, Mar 15, 2010 at 3:54 AM, Josh Smith <flappleja...@gmail.com>wrote:

>>>>>>> A while back Dr. WPF graced us with his clever hack of controlling
>>>>>>> input focus from VM objects.  It involved hijacking the VM's IDataErrorInfo
>>>>>>> implementation, and doing all sorts of evil-genius stuff to make the input
>>>>>>> caret move to the correct element.  Today while I was *trying* to
>>>>>>> read a great novel, I couldn't stop thinking about another way to control
>>>>>>> input focus from a viewmodel object.

>>>>>>> I put the novel down and did a quick spike of the idea.  The source
>>>>>>> code is attached (rename it from .DOC to .ZIP since gmail is terrified of
>>>>>>> ZIP files for some reason).  Here's the general idea...

>>>>>>> Implement this interface on your VM class:

>>>>>>>  /// <summary>
>>>>>>> /// Implemented by a ViewModel that needs to control
>>>>>>> /// where input focus is in a View.
>>>>>>> /// </summary>
>>>>>>> public interface IFocusController
>>>>>>> {
>>>>>>>     /// <summary>
>>>>>>>     /// Raised when the input focus should move to
>>>>>>>     /// a control whose 'active' dependency property
>>>>>>>     /// is bound to the specified property.
>>>>>>>     /// </summary>
>>>>>>>     event EventHandler<MoveFocusEventArgs> MoveFocus;
>>>>>>> }

>>>>>>> Next, in your VM object (which might implement IDataErrorInfo), do
>>>>>>> something like this to support a Save button:

>>>>>>>  public ICommand SaveCommand
>>>>>>> {
>>>>>>>     get { return new RelayCommand(this.Save); }
>>>>>>> }

>>>>>>> void Save()
>>>>>>> {
>>>>>>>     if (this.HasError)
>>>>>>>     {
>>>>>>>         // The Error property knows which property is invalid.
>>>>>>>         this.RaiseMoveFocus(this.Error);
>>>>>>>     }
>>>>>>>     else
>>>>>>>     {
>>>>>>>         // Save to database...
>>>>>>>         System.Windows.MessageBox.Show("Saved");
>>>>>>>     }
>>>>>>> }

>>>>>>> bool HasError
>>>>>>> {
>>>>>>>     get { return _validatedProperties.Any(prop =>
>>>>>>> !String.IsNullOrEmpty(this[prop])); }
>>>>>>> }

>>>>>>>  public event EventHandler<MoveFocusEventArgs> MoveFocus;

>>>>>>> void RaiseMoveFocus(string focusedProperty)
>>>>>>> {
>>>>>>>     var handler = this.MoveFocus;
>>>>>>>     if (handler != null)
>>>>>>>     {
>>>>>>>         handler(this, new MoveFocusEventArgs(focusedProperty));
>>>>>>>     }
>>>>>>> }

>>>>>>> Lastly, in your View, use my terribly(?) named attached property to
>>>>>>> specify which DP on your elements is bound to the validated property of the
>>>>>>> VM, for example:

>>>>>>>  <TextBox
>>>>>>>     Text="{Binding Path=FirstName, ValidatesOnDataErrors=True}"
>>>>>>>     *local:FocusControl.ValidatedProperty="TextBox.Text"*
>>>>>>>     />

>>>>>>> I'm not sure that I like this approach yet.  It's a pretty important
>>>>>>> topic, so I thought I'd share this out amongst the Disciples for feedback.

>>>>>>> Thanks,
>>>>>>> Josh

>>>>>> --
>>>>>> Peter O'Hanlon

>>>> --
>>>> Peter O'Hanlon

>> --
>> Peter O'Hanlon