C#•6mo ago

Accessing Function from Nested UI File - Avalonia

Ok so I have the following file structure for my Avalonia MVVM project

root/
|
| - Views/
| | - MenuBar/
| | | - FileMenu.axaml
| | - MainWindowView.axaml

root/
|
| - Views/
| | - MenuBar/
| | | - FileMenu.axaml
| | - MainWindowView.axaml

In my FileMenu.axaml file I have a menu option

<MenuItem Header="_Exit" />

<MenuItem Header="_Exit" />

I know to bind it to a command I would do

<MenuItem Header="_Exit" Command="{Binding Exit}" />

<MenuItem Header="_Exit" Command="{Binding Exit}" />

however, the exit function is in my MainWindowViewModel. So I have two questions. 1. Is it ok if I put the exit command in the FileMenu.axaml.cs file to exit the program? 2. If not, do I create a ViewModel file in the same directory as the FileMenu.axaml file and then call that code behind for all of my nested menu options? either way, if it's ok to stay in the MainWindowViewModel, then how do I properly bind to it? I remember in a Todo tutorial they did something like a this.Something.bind.x or something like that. Let me see if I can find it

12 Replies

Mekasu0124OP•6mo ago

this is it

<Button Grid.Row="2"
        Grid.Column="0"
        Grid.ColumnSpan="2"
        Command="{Binding $parent[Window].DataContext.AddItem}"
        Content="New Item"/>

<Button Grid.Row="2"
        Grid.Column="0"
        Grid.ColumnSpan="2"
        Command="{Binding $parent[Window].DataContext.AddItem}"
        Content="New Item"/>

I'm going to try that that didn't work, but basically I've got this menu bar

<DockPanel Grid.Row="0">
    <uc:FileMenu />
    <uc:EditMenu />
    <uc:SettingsMenu />
    <uc:HelpMenu />
</DockPanel>

<DockPanel Grid.Row="0">
    <uc:FileMenu />
    <uc:EditMenu />
    <uc:SettingsMenu />
    <uc:HelpMenu />
</DockPanel>

in my MainWindowView.axaml file which is a Window not a UserControl. I then have in my views folder a MenuBar folder that holds each menu bar item as a UserControl. In the /Views/MenuBar/FileMenu.axaml file I'm trying to bind the Exit menu item to the Exit function in the /ViewModels/MainWindowViewModel.cs file or put the exit command where it should go for a bound command to a menu bar item like I've used it......

Denis•6mo ago

Alternatively you could use messaging. If you are using community toolkit, then WeakReferenceMessenger allows you to send a message that any listener across your app can pickup and handle Eg, your close command will send the close messages,.and the main window will handle it

Mekasu0124OP•6mo ago

ohhhh like I did here

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using CommunityToolkit.Mvvm.Messaging;
using System.Collections.ObjectModel;
using System.Linq;
using System.Threading.Tasks;

namespace Diary.ViewModels;

public partial class MainViewModel : ViewModelBase
{
    [ObservableProperty] private string? _loggedInUserName;

    public MainViewModel()
    {
        Messenger.Register<UserLoggedInMessage>(this, UserLoggedIn);
    }

    [RelayCommand] public async Task Logout()
    {
        await Task.Delay(50);
        Messenger.Send(new UserLoggedOutMessage());
    }

    private void UserLoggedIn(object recipient, UserLoggedInMessage message)
    {
        LoggedInUserName = message.user.Username;
    }
}

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using CommunityToolkit.Mvvm.Messaging;
using System.Collections.ObjectModel;
using System.Linq;
using System.Threading.Tasks;

namespace Diary.ViewModels;

public partial class MainViewModel : ViewModelBase
{
    [ObservableProperty] private string? _loggedInUserName;

    public MainViewModel()
    {
        Messenger.Register<UserLoggedInMessage>(this, UserLoggedIn);
    }

    [RelayCommand] public async Task Logout()
    {
        await Task.Delay(50);
        Messenger.Send(new UserLoggedOutMessage());
    }

    private void UserLoggedIn(object recipient, UserLoggedInMessage message)
    {
        LoggedInUserName = message.user.Username;
    }
}

Mekasu0124OP•6mo ago

and the UserLoggedInMessage is defined in the MainWindowViewModel.cs file. but my other issue that may not even be an issue is that it's separate projects. One so far is console which is just a backend service and the other is the desktop app. Will it matter if I change the desktop app from Avalonia.ReactiveUI to CommunityToolkit.MVVM with my project structure looking like

TeachersAide/
  - src/
    - AddressBook/ (console)
    - GradeBook/
      - Assets/
      - ...

TeachersAide/
  - src/
    - AddressBook/ (console)
    - GradeBook/
      - Assets/
      - ...

Denis•6mo ago

Reactive UI has its own messaging framework - https://www.reactiveui.net/docs/handbook/message-bus.html You can always create a third project to share the message classes

Mekasu0124OP•6mo ago

with this part being mentioned of creating a messaging project, with having multiple projects in my src/ folder, when I go to package my project down to a .exe, how do I get the thing to recognize that package I want the .exe to always launch from? Example: If I have a Diary.Desktop, Diary.Infrastructure, and Diary.Common. When I package the project down to an executable, how do I get the .exe to know that Diary.Desktop is the source to launch from each time and not Common or Infrastructure?

Denis•6mo ago

Well the infrastructure and common are library projects, right? So it'll know automatically to start the executable application which is your Desktop project

Mekasu0124OP•6mo ago

I'm not sure if I set them up right. I right clicked the top TeachersAide and clicked New Project > Console > named it and created it

Denis•6mo ago

An executable project usually has a Program.cs You can always right click and view properties of a project. Or double click a project to view itd XML definition

Mekasu0124OP•6mo ago

ok so if I don't need a console project for let's say my Infrastructure project which is what handles all database executions and such, how and what would I make instead?

Denis•6mo ago

A class library a non-executable project

Mekasu0124OP•6mo ago

ah. thank you!

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Accessing Function from Nested UI File - Avalonia