CODEWITHSUNDEEP
wpfmvvmmvvm-light
Mahdi Salah
Mahdi Salah

Reputation: 189

How can I pass a variable between ViewModel using MVVM Light?

I have 2 Views the first one contain a list of users and the second where I can edit a user, all what I want is to pass the Id between the 2 ViewModel of each screen for I can know the user that will be modified. I'm a beginner working using the MVVM Light Framework, Can any one give me the best solution for this case ?

Upvotes: 1

Views: 1875

Answers (2)

M. Altmann
M. Altmann

Reputation: 726

Instead of using the messenger (using the messenger to often tends to messy your code) i would suggest to pass the id with the "Edit User" button/action and then use the id in the constructor of your target viewmodel.

Button in your view:

<Button Content="Edit" 
Command="{Binding DataContext.EditButtonCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=UserControl}}" 
CommandParameter="{Binding }" />

In your viewmodel:

public ICommand EditButtonCommand= new RelayCommand<object>(UseEditButton)

private async void UseEditButton(object obj)
{
        YourModel id = obj as YourModel;
    YourEditViewModel viewModel = new YourEditViewModel(id) 
    //navigate to vm
}

Upvotes: 1

Jehonathan Thomas
Jehonathan Thomas

Reputation: 2200

First wrap your variable inside a class.

 public class VariableMessage
 {
       public string YourVariable { get; set; }
 }

Then to receive message register in the receiving view model initializer.

 Messenger.Default.Register<VariableMessage>
           (
                this,
                (action) => ReceiveVariableMessage(action)
           );

 private object ReceiveVariableMessage(VariableMessage variableMessage)
 {
      Console.WriteLine(variableMessage.YourVariable);
      return null;
 }

To send message 

 Messenger.Default.Send<VariableMessage>(new VariableMessage() { YourVariable = "Hello"});

Upvotes: 4

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