Question

Initially I wanted to pass an “ObservableCollection< customClass>” between two VMs , but even simple messaging isn’t working for me.

MainViewModel

 private void openNewSpecialCustomer()
    {
        GalaSoft.MvvmLight.Messaging.Messenger.Default.Send("Musaab");
        Console.WriteLine("send done");
        AddNewSpecialCustomer a = new AddNewSpecialCustomer();
        _dialogService.showDialoge(a);
    }

AddNewSpecialCustomerViewModel

public AddNewSpecialCustomerViewModel()
    {
        GalaSoft.MvvmLight.Messaging.Messenger.Default.Register<string>(this,  doSomething);
        Console.WriteLine("Should now Receive");
        validProperties = new Dictionary<string, bool>();
        validProperties.Add("specialCustomerName",false);
        validProperties.Add("tel", false);
        allPropertiesValid = false;

    }

    public void doSomething(string s)
    {
        Console.WriteLine("Should be received");
        specialCustomerName = s;
        Console.WriteLine("s value " + s);
    }

    public String specialCustomerName
    {
        get { return _specialCustomerName; }
        set
        {
            if (_specialCustomerName != value)
            {
                _specialCustomerName = value;
               OnPropertyChanged("specialCustomerName");

            }
        }
    }

now XAML for AddNewSpecialCustomer

<Window FlowDirection="RightToLeft" x:Class="GlassStore.AddNewSpecialCustomer"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:local="clr-namespace:GlassStore.ViewModels"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="AddNewSpecialCustomer" Height="318" Width="458">

<Window.DataContext>
    <local:AddNewSpecialCustomerViewModel/>
</Window.DataContext>
<Grid Background="{DynamicResource NormalBrush}">
    <Button Command="{Binding Save}" Content="موافق" Height="29" HorizontalAlignment="Left" Margin="31,218,0,0" Name="button1" VerticalAlignment="Top" Width="75" />
    <Label Content="إسم العميل" Height="27" HorizontalAlignment="Left" Margin="12,12,0,0" Name="label1" VerticalAlignment="Top" Width="120" />
    <TextBox Text="{Binding specialCustomerName,Mode=TwoWay,ValidatesOnDataErrors=True,ValidatesOnExceptions=True,UpdateSourceTrigger=PropertyChanged}" Height="27" HorizontalAlignment="Left" Margin="155,12,0,0" Name="textBox1" VerticalAlignment="Top" Width="210" />
    <Label Content="المنطقة/المكان" Height="27" HorizontalAlignment="Left" Margin="12,67,0,0" Name="label2" VerticalAlignment="Top" Width="120" />
    <TextBox Text="{Binding region}" Height="27" HorizontalAlignment="Left" Margin="155,67,0,0" Name="textBox2" VerticalAlignment="Top" Width="210" />
    <TextBox Text="{Binding tel,ValidatesOnDataErrors=True,ValidatesOnExceptions=True,UpdateSourceTrigger=PropertyChanged}" Height="27" HorizontalAlignment="Left" Margin="155,119,0,0" Name="textBox3" VerticalAlignment="Top" Width="210" />
    <Label Content="رقم الهاتف " Height="27" HorizontalAlignment="Left" Margin="12,119,0,0" Name="label3" VerticalAlignment="Top" Width="120" />
    <Button Content="إلغاء" Height="29" HorizontalAlignment="Left" Margin="143,218,0,0" Name="button2" VerticalAlignment="Top" Width="75" />
    <Label Content="" Height="29" HorizontalAlignment="Left" Margin="12,177,0,0" Name="label4" VerticalAlignment="Top" Width="412" />
</Grid>

you can see that there is textBox, with a Text property bounded to specialCustomerName Property , which I’m trying to change it via the messenger , the data-bind mode is TwoWay, so I expect my textBox to have my name on it when loaded , (I’m sending my name via the messenger) which is not the case, I hope this may be more clear code

thanks in advance

Answer 1

Is your second window constructor called after the first one ?
You should first register and only then send the message. Previously sent messages are not received. Sorry for being C.O. but this kind of mistake is rather possible 🙂