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New Post: ElementWrapper, care to elaborate a little ?

s093294 — Sun, 31 Mar 2013 01:00:53 GMT

I do want to databind, but could not make it work with selected items. I have a button and when it is clicked a new viewmodel is added to my TabItemsViewModelsCollection which will add a new tab to my TabControl. My Problem was to get the Command and CommandParameter to work on the button.

I had something like <button CommandParameter="{Binding SelectedItem ,ElementName=MyListView}" Command="{Binding OpenTabCommand}"> ...

While reproducing my error it hit me that the problem was i had bound it to SelectedItem isntead of Selecteditems, which made the eventcommand CanExecute return false and not being set to true. Changing it to SelectedItems and handing Count>0 in my Command delegate solved my problems.

Thanks for the discussion, helped me a lot.

New Post: ElementWrapper, care to elaborate a little ?

mglukhankov — Sun, 31 Mar 2013 00:52:11 GMT

Elements is protected on purpose so you cannot break the rules.

Do not use wrappers where you can use bindings. Selected items should be bound.

Multiple elements come from multiple bindings.

New Post: ElementWrapper, care to elaborate a little ?

s093294 — Sat, 30 Mar 2013 23:49:25 GMT

Okay

I have a case here where i had a button that when clicked it should open a new tab in a tabcontrol based on the item selected in a listview.
First i tried to use a command, EventCommand and CommandParameter resulting in the button being set to disabled because canExecute returned false the first time when no items was selected in the list. Instead i tried binding just a command with a RelayCommand, but then i had to have a wrapper for the listview to get the selected item in my model.

So making the Elements public on the Wrapper was a lot easier then writing these intermediate layers, but i do see your argument.

I havent been able to figure out why you have a Set of Elements in the wrappers? In what situation can there be more than one element in a wrapper? My guess is that you can bind two elements to the same wrapper, but why would one do that?

New Post: ElementWrapper, care to elaborate a little ?

mglukhankov — Sat, 30 Mar 2013 22:59:28 GMT

This will break the whole idea of mvvm. A model should not know about its view.
But a wrapper is in an intermediate layer that can work without a view and can be replaced with something else in e.g. unit tests.

New Post: ElementWrapper, care to elaborate a little ?

s093294 — Sat, 30 Mar 2013 21:04:24 GMT

I have been using some of your ideas in my own WPF applicatino and Windows 8 store apps as i have found it intuitive to use.

But this question i havent been able to answer my self.

I get the idea of wrapping Views back to Model and your example for Focus is fine.
But why is the element protected in ElementWrapper, meaning that whenever someone want to do this on something else then focus he have to extend your code?

Would it not make sense to have the wrapper just expose the view element directly to be used in the model ?

New Post: How to bind against a event that are not supported?

mglukhankov — Wed, 27 Mar 2013 15:17:16 GMT

Thanks. I've added DragItemsStarting too.

New Post: How to bind against a event that are not supported?

s093294 — Wed, 27 Mar 2013 12:56:31 GMT

I just vent over your code. I implemented something similar yesterday when i wrote the post. But i used DragItemsStarting for getting the items from gridview.

I will leave en update here when i get around to download and test the updates you made.

New Post: How to bind against a event that are not supported?

mglukhankov — Wed, 27 Mar 2013 02:47:45 GMT

I've added 4 new events for D&D. Could you please download the latest release 1.0.0.6 and try it out?

P.S. I did not update the NuGet and project template yet.

New Post: How to bind against a event that are not supported?

s093294 — Tue, 26 Mar 2013 17:25:07 GMT

I want to bind against the drop event, but i do not seem to find it in the Mvvm:EventBinding?

New Post: Passing query string and overriding save state and restore state

mglukhankov — Tue, 05 Mar 2013 15:36:15 GMT

There is an article in the documentation.

New Post: Passing query string and overriding save state and restore state

stephanronald — Tue, 05 Mar 2013 14:08:32 GMT

Save and restore state.

Can you please demonstrate the way you save the page state values. My major concern is with saving page state values based on the active frame. (Ie how i can enc operate state of a particular viewmodel to my active frame like MS did in Layout aware page.

New Post: Passing query string and overriding save state and restore state

mglukhankov — Mon, 04 Mar 2013 15:48:02 GMT

Save and restore state:
You do not have to duplicate the code in each page. Simply move this functionality to a base class.
We have no problems in large projects here. And we've done several projects already.

Backstack removal:
So, what is the problem? You can navigate between your pages in any order. And for your convenience we added the NavigationState.Reset() method. This method will clear the navigation history if you need it.

New Post: Passing query string and overriding save state and restore state

stephanronald — Mon, 04 Mar 2013 09:15:43 GMT

Yup i managed to get the first point working... What about the remaining two points.?

New Post: Passing query string and overriding save state and restore state

mglukhankov — Sun, 03 Mar 2013 09:32:23 GMT

Could you please tell me what you are trying to achieve? Why can't you add a method to your model with the required parameter?

New Post: Passing query string and overriding save state and restore state

stephanronald — Sun, 03 Mar 2013 06:34:17 GMT

Passing query string while navigation

How do i pass query string values while navigation through your project template. I didn't find any method that accepts query string parameters.

Save state and restore state.

I fond your response for this in the last thread. Like rkshnair said, i think for a large project, it will not be a better solution (like registering suspending events in view model). Can you please make this global like MS did with Save state and restore state along with suspension manager. If you add that functionality to the template i think it will be more perfect for large projects that deals with many number of pages.

If you didn't add such functionality, I think preferably writing code on code behind is better choice than this project. Because if we cannot make use of such an important feature how we can say the template is complete.

Backstack removal

My last doubt is how i can remove the backstak in windows 8. Is there any supported methods are available in this project template. For example my requirement is, i need a navigation structure like this, (a -> B, B-> C, C->A) I set the option of cash mode enabled in my project.

New Post: Persisting Navigation and Handling state values

mglukhankov — Sun, 24 Feb 2013 16:42:56 GMT

@rkshnair : You do not have to duplicate a code. There are plenty of programming techniques to avoid a code duplication. But this is a good feature to have. We probably will address this in next releases.
About dynamic class creation: of course you can make your view models static (they are already static in the template), but you asked about SimpleIOC container and I provided you with some choices.

New Post: Persisting Navigation and Handling state values

ygrik — Fri, 22 Feb 2013 17:57:03 GMT

I've updated NuGet package

New Post: Persisting Navigation and Handling state values

mglukhankov — Fri, 22 Feb 2013 14:55:56 GMT

I've implemented a fix.
You can download the recommended download (1.0.0.5) and change the reference to the assembly.
NuGet package and VS project template will be updated soon.

New Post: Persisting Navigation and Handling state values

stezpet — Fri, 22 Feb 2013 14:22:13 GMT

@rkshnair : Yes you are right, now only i noticed the issue. How i can fix this issue in my application. I also noticed your suggestions, Now i feel really afraid? Do i face any issue while using this template. Now my 50% of development is completed. Is it possible to migrate my project to any other framework without affecting my structure. Can you please suggest some UI design architectures that is stable for design. I am really new to this field and i am confused with mvvm. The issue is that my client is sticking with MVVM structure. Otherwise i opt writing code behind.

New Post: Persisting Navigation and Handling state values

rkshnair — Fri, 22 Feb 2013 06:55:23 GMT

@Stez : The method you following is not completely right. If you follow this method you will get your view persisted. But after coming from the terminated state you will not get any page state events get fired on your implementation. So if you need to load any web request or db hit you cannot make the call.

@mglukhankov : The implementation you mentioned above seems to be pretty ordinary. If you make the change inside of pagemodel / viewmodel (base claas). We can make use of the page events for all the views. Also state handling can handled based on the current active frame. But as per you suggestion we need to register suspending events in all views so the code is duplicating and we need to write the state handling code (serialization / deserialization) method in all pages. I don't think it would be a better method to suggest.

About dynamic class creation:

If you are creating all the objects for viewmodel in the Bootstrap class (say in your RootModel) what is the advantage, In my point of view if you create an on demand view model creation that would be more wired for your project template. Otherwise why can't you make your viewmodel static.