MahApps/MahApps.Metro

Albvadi

@Albvadi

I followed the v4 HamburguerMenu with MVVM example from the code-samples and all it´s working correctly. But now, I need made global changes across from any view in the application and I don´t know what it´s the best form...

For example, in the About view in the viewModel, I have a button and I need to disable a element from the hamburguerMenu.
I thought to remove the readonly modifier here and make the changes directly in the mainViewModel...

It´s the correct way? There are better options to do this??

Twitter Tweets

@mrjakepavek_gitlab

did you make them static?

public static

Albvadi

@Albvadi

no, in the mainViewModel are public collections declared here

Twitter Tweets

@mrjakepavek_gitlab

yes in the viewmodel

did you declare the namespace?

Albvadi

@Albvadi

declare the namespace? don´t understand what you mean...

When I said "make the changes directly in the mainViewModel" I mean something like this:

Twitter Tweets

@mrjakepavek_gitlab

xmlns:view="clr-namespace:wpfapp.Views"

Albvadi

@Albvadi

in AboutViewModel.cs

public readonly MainViewModel _mainViewModel; // <-- remove readonly

public DisableElement(PropertyChangedViewModel mainViewModel)
{
    (MainViewModel)mainViewModel.MenuItems.GetItem(0).IsEnabled = false;
}

and yes, I´ve declared the namespace in the xaml

Tim

@timunie

Hi @Albvadi I use the ICommand-Interface if I want to disable or enable Buttons based on whatever

Albvadi

@Albvadi

Yes, I made this with Icommand, but my doubt it´s the method to access to the menu Items.. It´s the correct way remove the readonly modifier and setting directly in the mainViewModel from other viewModel?

Tim

@timunie

If it works, why not?

normaly ICommand has CanExecute and will disable the MenuItem if needed

Albvadi

@Albvadi

because the MVVM pattern... according to what I have read, each viewModel must have his own methods and properties and only set that, not set the properties from others viewModel

Tim

@timunie

Ok I am not a programmer by profession, so I try to do it this way, but sometimes I mix it up like you. If a real programmer would run away crying loud, I don't know :-) . I think it should be obvious what is going on and reliable . Then it would be OK from my point of view

Albvadi

@Albvadi

If a real programmer would run away crying loud, I don't know :-) .

:joy: :joy: :joy:

I think the same, I try to do the best, but it´s very frustrating when you arrive new to a new programmic language world and I ended mix it up to get working...

Tim

@timunie

@Albvadi can you show us a sample code or is it not public?

'''c#
public DisableElement(PropertyChangedViewModel mainViewModel)
{
(MainViewModel)mainViewModel.MenuItems.GetItem(0).IsEnabled = false;
}
'''

this is not ICommand

Here is a sample class for ICommand-implementation

    public class RelayCommand : ICommand
    {
        private Action<object> execute;

        private Predicate<object> canExecute;

        private event EventHandler CanExecuteChangedInternal;

        public RelayCommand(Action<object> execute) : this(execute, DefaultCanExecute)
        {
        }

        public RelayCommand(Action<object> execute, Predicate<object> canExecute)
        {
            this.execute = execute ?? throw new ArgumentNullException(nameof(execute));
            this.canExecute = canExecute ?? throw new ArgumentNullException(nameof(canExecute));
        }

        public event EventHandler CanExecuteChanged
        {
            add
            {
                CommandManager.RequerySuggested += value;
                this.CanExecuteChangedInternal += value;
            }

            remove
            {
                CommandManager.RequerySuggested -= value;
                this.CanExecuteChangedInternal -= value;
            }
        }

        public bool CanExecute(object parameter)
        {
            return this.canExecute != null && this.canExecute(parameter);
        }

        public void Execute(object parameter)
        {
            this.execute(parameter);
        }

        public void OnCanExecuteChanged()
        {
            EventHandler handler = this.CanExecuteChangedInternal;
            if (handler != null)
            {
                handler.Invoke(this, EventArgs.Empty);
            }
        }

        public void Destroy()
        {
            this.canExecute = _ => false;
            this.execute = _ => { return; };
        }

        private static bool DefaultCanExecute(object parameter)
        {
            return true;
        }

Tim

@timunie

You can use it like a Property on your VM-Classes

Albvadi

@Albvadi

this is not ICommand

Was only an example how to access to the mainViewModelProperty.. I can prepare an example with the v4 hambuerguerMenu as the project base and using ICommand and discuss how to modify a global variable (or a menu item) from any view

Tim

@timunie

You don't need to, I was just wondering

Albvadi

@Albvadi

It is not a nuisance, It suits me very well to acquire knowledge and know how other developers solve these problems

I´ll do it tomorrow and I´ll ping you.. :)

sgamescz

@sgamescz

Hello everybody. Quick question about this.ShowMessageAsync("aaa", "bbb");. This works from main WPF form. but i want call showmessageasync from my viewmodels, which are displayed in main form thru hamburgermenu.

but this. , me. etc.. dont exist in views or in viewmodel.cs

MatthPicker

@MatthPicker_twitter

Hi everyone, I am using a HamburgerMenuItem for which I set the IsPaneOpen to a bool of my viewmodel. It works great. Now, I'd like to have this pane closed by default and have it open when the user hovers his mouse onto it. I can't make it work: the mouseEnter and mouseLeave events set on the HamburgerMenu.ItemTemplate node work only when you are on the actual label of the menu item, but not on the whole panel. Any idea? :-)

gandol2

@gandol2

Tim

@timunie

@sgamescz use IDialogCoordinator (https://mahapps.com/controls/dialogs.html)

@MatthPicker_twitter you can try to create a Style and set a Trigger on IsMouseOver

(untested)

@gandol2 Hi

MatthPicker

@MatthPicker_twitter

Thanks @timunie . Is it possible to use ShowInputAsync with only one button (ok)

Tim

@timunie

Sorry, I don't know.

MatthPicker

@MatthPicker_twitter

thanks anyways :-)

Tim

@timunie

You can test it in the demo App

MatthPicker

@MatthPicker_twitter

I guess I have to create a custom message box dialog

simply surprised it does not come out of the box

Tim

@timunie

Yeah... freetime project, so the developer do what they need.

MatthPicker

@MatthPicker_twitter

did not mean to criticize, this is absolutely wonderful

thanks to everyone involved

I love playing with this and leaning WPF in the same time

learning

sgamescz

@sgamescz

@MatthPicker_twitter me too :-D i have same feeling ... thanks @timunie and other for helping us !

Tim

@timunie

@MatthPicker_twitter It was more meant as an explanation. Additions are welcome, if they fit into the design and API

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