Jim T

I have a class which only has a private constructor (a singleton), where I
have a public static property named Instance which returns the one and only
class.

When I attempt to databind, this class does not show up in the "clr" list of
classes (I'm guessing because it's got a private constructor).

Anybody have any ideas on how I would databind to this class using blend?
I'm guessing it would be some sort of custom expression, but have
experimented and failed so far.

Thanks
--
Jim

Corrado Cavalli [MVP]

Have you tried adding manually an ObjectDataProvider to Window Resources,
ObjectDataProvider can bind to static methods.

--
Corrado Cavalli [Microsoft .NET MVP-MCP]
UGIdotNET - http://www.ugidotnet.org
Weblog: http://blogs.ugidotnet.org/corrado/

Jim T

Wow Corrado, pointing me to ObjectDataProvider sure made for a busy day of
research and test coding... this is weighty stuff.

I've almost got this working, but just a bit short on a "complete solution".
Here's what I have so far...

1. I have a singleton derived from ObservableCollection, and it has a method
named "GetInstance" which will return the one-and-only instance.

2. In my App.xaml file, I have manually added 2 lines:
a) xmlns:Sample="clr-namespaceBSample"
b) In the Application.Resources have added:
<ObjectDataProvider MethodName="GetInstance" ObjectType="{x:Type
Sample:ContactCollection}" x:Key="ContactCollectionSingleton"/>

I have built a window to display a listbox where I have populated the
ContactCollection with sample data. This window consists of the layoutroot,
a child grid, and a listbox in that grid. Following is the steps in Blend I
used to make this work:

1. When setting the grid's DataContext, I found that the proper context can
be set from the "Local Resources" selection, where
"ContactCollectionSingleton" was present. (While this is different from the
normal "Select DataBinding, and bind to a clr object" step, this is something
I feel I can sell to our designers.)

2. When setting the listbox's "ItemSource", the only way I could get this to
work was to select "Custom Expression" and type in the following:
{Binding Mode=OneWay, Source={StaticResource ContactCollectionSingleton}}

This actually works, and the listbox displays the data as it should when
run, but the step of typing in a custom expression is far from designer
friendly.

Can you think of anything I can do to be able to present this data to Blend
in such a way that there is something to select under the normal "Create Data
Binding" window you get when you select "Data Binding"?

I don't think it's too much of a problem to manually add the resource I
added into the App.xaml file... this just seems like more of a workflow
issue, where when I create a new singleton that is bindable, I also edit
App.xaml to expose it to blend... no problem. But having the
"non-programmer" designers (who can handle quite a bit) type in that custom
expression is not going to make me any friends, not to mention its very prone
to error.

Thanks for the help so far, it was an interesting day of study so far.

--
Jim


"Corrado Cavalli [MVP]" wrote:

> Have you tried adding manually an ObjectDataProvider to Window Resources,
> ObjectDataProvider can bind to static methods.
>
> --
> Corrado Cavalli [Microsoft .NET MVP-MCP]
> UGIdotNET - http://www.ugidotnet.org
> Weblog: http://blogs.ugidotnet.org/corrado/
>
>

Corrado Cavalli [MVP]

This is one of the areas where Blend might improve...
Regarding binding: If you associate data to Grid's DataContext and listbox
is inside the grid you can just use (via Custom Expression)
ItemsSource={Binding}.
Regarding design time data: You have to modify your class so that when
instantiated at design time by Blend (that's what really happens under the
hood) it provides sono dummy data.
You can find a detailed sample here:
http://www.galasoft.ch/mydotnet/arti...007091401.html

--
Corrado Cavalli [Microsoft .NET MVP-MCP]
UGIdotNET - http://www.ugidotnet.org
Weblog: http://blogs.ugidotnet.org/corrado/

Jim T

Thanks Corrado, that did the job! And thank you for the added link for
design time data... that was a great addition to your response. This is
100% inline with my desire to provide the best design time experience I am
able to.

--
Jim


"Corrado Cavalli [MVP]" wrote:

> This is one of the areas where Blend might improve...
> Regarding binding: If you associate data to Grid's DataContext and listbox
> is inside the grid you can just use (via Custom Expression)
> ItemsSource={Binding}.
> Regarding design time data: You have to modify your class so that when
> instantiated at design time by Blend (that's what really happens under the
> hood) it provides sono dummy data.
> You can find a detailed sample here:
> http://www.galasoft.ch/mydotnet/arti...007091401.html
>
> --
> Corrado Cavalli [Microsoft .NET MVP-MCP]
> UGIdotNET - http://www.ugidotnet.org
> Weblog: http://blogs.ugidotnet.org/corrado/
>
>