> 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