Vista - How to reset datacontext to parent datacontext

Hi,

I'm trying to suspend binding for the controls of a groupbox. To do that I
set its datacontext to null (nothing).
That's the first point that surprises me. It works ! I'm surprised
because I expected to see the groupbox retrieve its parent datacontext due
to dependency property inheritance mechanism. What do I miss there ?

But here comes the corollary problem : how to reset the datacontext to the
one of its parent ? If I try to force it with (vb code, sorry):
mygroupbox.datacontext = ctype(mygroupbox.parent,
frameworkelement).datacontext

it works... till the parent datacontext changes. The groupbox datacontext is
not linked (bound) to it.


How to achieve that ? What I want is just the default behavior after all. I
tried with DefaultMetadata.DefaultValue but it returns null and so doesn't
resolve my problem.

I have a working solution by binding the two datacontexts but I guess
there's something more direct (an ad-hoc method or something).

Thanx in advance.

Ok I think I got it. It seems that the ClearValue method does the trick.
Right ?


"Pon" <pongla.public@laposte.net> a écrit dans le message de news:
uQeMz$o9GHA.4740@TK2MSFTNGP03.phx.gbl...
> Hi,
>
> I'm trying to suspend binding for the controls of a groupbox. To do that I
> set its datacontext to null (nothing).
> That's the first point that surprises me. It works ! I'm surprised
> because I expected to see the groupbox retrieve its parent datacontext due
> to dependency property inheritance mechanism. What do I miss there ?
>
> But here comes the corollary problem : how to reset the datacontext to the
> one of its parent ? If I try to force it with (vb code, sorry):
> mygroupbox.datacontext = ctype(mygroupbox.parent,
> frameworkelement).datacontext
>
> it works... till the parent datacontext changes. The groupbox datacontext
> is not linked (bound) to it.
>
>
> How to achieve that ? What I want is just the default behavior after all.
> I tried with DefaultMetadata.DefaultValue but it returns null and so
> doesn't resolve my problem.
>
> I have a working solution by binding the two datacontexts but I guess
> there's something more direct (an ad-hoc method or something).
>
> Thanx in advance.
>
>

Yup - you got it. There is most definitely a difference between a value
which is set (even if to null) and one which is not. As you found, setting
a local value - even null - overrides inheritance. And, as you found,
ClearValue "unsets" a local value, allowing inheritance to kick in again.

-Adam Smith [MS]

"Pon" <pongla.public@laposte.net> wrote in message
news:OIo59Fp9GHA.3352@TK2MSFTNGP03.phx.gbl...
> Ok I think I got it. It seems that the ClearValue method does the trick.
> Right ?
>
>
> "Pon" <pongla.public@laposte.net> a écrit dans le message de news:
> uQeMz$o9GHA.4740@TK2MSFTNGP03.phx.gbl...
>> Hi,
>>
>> I'm trying to suspend binding for the controls of a groupbox. To do that
>> I set its datacontext to null (nothing).
>> That's the first point that surprises me. It works ! I'm surprised
>> because I expected to see the groupbox retrieve its parent datacontext
>> due to dependency property inheritance mechanism. What do I miss there ?
>>
>> But here comes the corollary problem : how to reset the datacontext to
>> the one of its parent ? If I try to force it with (vb code, sorry):
>> mygroupbox.datacontext = ctype(mygroupbox.parent,
>> frameworkelement).datacontext
>>
>> it works... till the parent datacontext changes. The groupbox datacontext
>> is not linked (bound) to it.
>>
>>
>> How to achieve that ? What I want is just the default behavior after all.
>> I tried with DefaultMetadata.DefaultValue but it returns null and so
>> doesn't resolve my problem.
>>
>> I have a working solution by binding the two datacontexts but I guess
>> there's something more direct (an ad-hoc method or something).
>>
>> Thanx in advance.
>>
>>
>
>

Thanx for confirming.

"Adam Smith [MS]" <Adam.Smith@microsoft.com> a écrit dans le message de
news: OGQRXU49GHA.748@TK2MSFTNGP02.phx.gbl...
> Yup - you got it. There is most definitely a difference between a value
> which is set (even if to null) and one which is not. As you found,
> setting a local value - even null - overrides inheritance. And, as you
> found, ClearValue "unsets" a local value, allowing inheritance to kick in
> again.
>
> -Adam Smith [MS]
>
> "Pon" <pongla.public@laposte.net> wrote in message
> news:OIo59Fp9GHA.3352@TK2MSFTNGP03.phx.gbl...
>> Ok I think I got it. It seems that the ClearValue method does the trick.
>> Right ?
>>
>>
>> "Pon" <pongla.public@laposte.net> a écrit dans le message de news:
>> uQeMz$o9GHA.4740@TK2MSFTNGP03.phx.gbl...
>>> Hi,
>>>
>>> I'm trying to suspend binding for the controls of a groupbox. To do that
>>> I set its datacontext to null (nothing).
>>> That's the first point that surprises me. It works ! I'm surprised
>>> because I expected to see the groupbox retrieve its parent datacontext
>>> due to dependency property inheritance mechanism. What do I miss there ?
>>>
>>> But here comes the corollary problem : how to reset the datacontext to
>>> the one of its parent ? If I try to force it with (vb code, sorry):
>>> mygroupbox.datacontext = ctype(mygroupbox.parent,
>>> frameworkelement).datacontext
>>>
>>> it works... till the parent datacontext changes. The groupbox
>>> datacontext is not linked (bound) to it.
>>>
>>>
>>> How to achieve that ? What I want is just the default behavior after
>>> all. I tried with DefaultMetadata.DefaultValue but it returns null and
>>> so doesn't resolve my problem.
>>>
>>> I have a working solution by binding the two datacontexts but I guess
>>> there's something more direct (an ad-hoc method or something).
>>>
>>> Thanx in advance.
>>>
>>>
>>
>>
>
>