An MVVM button event with a list view not getting the selected item

Question

I am trying to get the selectedItem from my list view. I am using MVVM light toolkit and the EventToCommand on a button.

My listView is bound to an ObservableCollection which is correctly binding. Here is the listView xaml:

  <ListView   Name="serverListView"
                    Grid.Row="3"
                    Grid.Column="0"
                    Grid.ColumnSpan="2"
                    ItemsSource="{Binding Servers}"
                    ItemTemplate="{StaticResource ServerList}"
                    SelectionMode="Single"
                    BorderThickness="0"/>

I then have a button which I am using Interaction.Triggers with a mvvm EventToCommand, I am not sure if the selectedItem binding is correct. The event is firing correctly through a Relay Command (mvvm light toolkit) but I am getting null every time.

Here is my button xaml;

<Button x:Name="LoadButton"
                Content="Load Server"
                Grid.Column="0"
                Grid.Row="4"
                Grid.ColumnSpan="2">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="Click">
                    <mvvm:EventToCommand  Command="{Binding ButtonClick, Mode=OneWay}"
                                            CommandParameter="{Binding SelectedItem, ElementName=serverListView}"
                                            MustToggleIsEnabledValue="True"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </Button>

Relay Command:

 this.ButtonClick = new RelayCommand<object>(new Action<object>(this.GetClickEvent));

why do you need an eventtocommand behavior over here? just use the button´s Command/CommandParameter properties — Joachim Kerschbaumer, Jun 14 '12 at 11:56

score 1 · Answer 1 · answered Jun 14 '12 at 10:41

get rid of the commandparameter binding, create a SelectedServer property in your viewmodel and the Command in your viewmodel without parameter

<ListView   Name="serverListView"
                Grid.Row="3"
                Grid.Column="0"
                Grid.ColumnSpan="2"
                ItemsSource="{Binding Servers}"
                ItemTemplate="{StaticResource ServerList}"
                SelectedItem="{Binding SelectedServer}"
                SelectionMode="Single"
                BorderThickness="0"/>

<Button Command="{Binding MyCommand}" />

in your viewmodel you have all information you need to do your command logic.

mathieu · Accepted Answer · 2012-06-14T10:27:15.377

0

You should as well bind the SelectedItem property of the listview to a property (SelectedServer) of your viewmodel, and change your EventToCommand

CommandParameter="{Binding SelectedItem, ElementName=serverListView}"

to

CommandParameter="{Binding SelectedServer}"

edited Jun 14 '12 at 10:27

answered Jun 14 '12 at 10:15

mathieu

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An MVVM button event with a list view not getting the selected item

2 Answers2